CPC · California Plumbing Code

Definitions for traps, interceptors and related devices

Q: What if I can’t find §§ 216.0 or 217.0 in my copy of the CPC?

I could not locate § 216.0 or § 217.0 in the uploaded CPC files. Use the Chapter 10 trap and interceptor sections (examples: § 1001.2 , § 1005.1 , § 1009.1 ) and Definitions § 222.0 as the governing text for traps and interceptors.

Q: Minimum and maximum trap seal depths — what are they?

Each fixture trap must have a liquid seal of not less than 2 inches and not more than 4 inches , unless the AHJ requires a deeper seal. § 1005.1 .

Q: Are floor drains required to have trap primers?

Floor drains or similar traps subject to infrequent use shall be protected with a trap‑seal primer unless the AHJ says it’s unnecessary; primers must be accessible for maintenance. § 1007.1 .

Q: How do I size a grease interceptor?

Use Table 1014.3.6 (DFUs → interceptor volume) or size by actual (peak) flow rate × 30 minutes retention and select the next nominal volume. See the code example (12 DFU → 750 gallons). § 1014.3.6 .

Traps are plumbing fittings that form a liquid seal to block sewer gas. The CPC requires most traps to have a 2"–4" liquid seal, tailpieces no longer than 24", primers for infrequently used floor drains, and interceptors for grease/sand/oil sized by DFUs or flow — see Chapter 10 (e.g., § 1005.1, § 1007.1, § 1009.1) and Definitions § 222.0 for exact text and required standards.

Ask a question free See coverage

Last reviewed: July 6, 2026

What the code requires — plain English (controlling sections)

The uploaded California Plumbing Code (CPC) files did not contain § 216.0 or § 217.0 (I could not locate those exact section numbers in the provided documents). Instead, the CPC’s operative requirements and definitions for traps, trap seals, trap primers, tailpieces, and interceptors are found in Chapter 10 (notably § 1001.2, § 1004.1, § 1005.1, § 1007.2, and § 1009.1) and in the Definitions section (see § 222.0). Use those sections as the controlling text for design and inspection.

The single most important point: a trap must provide and maintain a liquid seal sized and protected per code so sewer gases cannot enter the building — see the Code’s definitions and trap‑seal limits.

Requirements in detail

Key defined terms (first mentions are bold)

Trap — a fitting or device that, when properly vented, provides a liquid seal to prevent the back‑passage of air/sewer gas without materially restricting flow (Definitions, § 222.0).
Trap Seal — the vertical distance between the crown weir (trap weir) and the top dip of the trap; this is the liquid depth that blocks gases (Definitions, § 222.0).
Trap Primer — device or piping system used to maintain a trap seal where the trap is infrequently used (Definitions, § 222.0; primer standards in § 1007.2).
Tailpiece — the pipe/tubing connecting a fixture outlet to a trap (Definitions, § 222.0).
Interceptor (Clarifier) — device (grease, oil, sand, solids) required where wastes would otherwise harm the drainage/sewer system; sizing, access, and venting rules apply (see § 1009.1, § 1009.3 and gravity‑grease rules).

Concrete numeric limits and controls (summary table)

Decision dimension	Required value / limit	Code Reference
Trap seal depth (minimum)	2 inches (51 mm)	§ 1005.1
Trap seal depth (maximum)	4 inches (102 mm) (unless AHJ requires deeper)	§ 1005.1
Tailpiece maximum length	24 inches (610 mm) from fixture outlet to trap weir	§ 1001.2
Trap must be vented / protected against siphonage	Venting per Chapter 9; trap arms limited by developed length tables	§ 1002.1 and Table 1002.2
Prohibited trap types / devices	Traps with movable parts (bladders, check valves), “S” traps, crown‑vented traps, etc., are prohibited	§ 1004.1
Interceptor (sand) trap seal	Not less than 6 inches (152 mm) water seal for sand/solid interceptors	§ 1009.3
Interceptor sizing (kitchen grease, gravity)	Use Table 1014.3.6 (DFUs → gallon capacity) or DFU/flow method (30‑minute retention)	§ 1014.3.6 and Table 1014.3.6
Interceptor access	Covers and location must allow ready access for cleaning; not installed where inaccessible	§ 1009.5; gravity grease location rules § 1014.3.4

Notes:

"AHJ" means Authority Having Jurisdiction — the code repeatedly allows the AHJ to require deeper seals or approve alternatives.
Venting design (to prevent siphonage or >1 in. water‑column pressure differential on a trap) is covered in Chapter 9 (e.g., trap seal protection limits).

Traps — material & installation highlights

Traps shall be self‑scouring and of approved materials (ABS, brass, cast‑iron, PVC, etc.) except where special traps are permitted; exposed copper alloy traps have a minimum gauge when used. § 1003.1.
Not more than one trap on a trap arm; fixtures normally require separate traps (exceptions for lavatory sets and certain sink groups explained in § 1001.2). § 1001.2.

Trap seal protection & primers

Floor drains and similar traps subject to infrequent use must have trap seal primers unless AHJ decides otherwise; primers must be accessible for maintenance. § 1007.1.
Potable water supply primers must comply with ASSE 1018; drainage or electronic primer devices must comply with ASSE 1044 or IAPMO PS 76. § 1007.2.

Interceptors (clarifiers) — where to use and how to design

An interceptor is required where liquid wastes contain grease, flammable wastes, sand, solids, acids/alkalis, or other harmful ingredients — the AHJ determines necessity. § 1009.1.
Sand interceptors must have a water seal ≥ 6 inches (152 mm) and be readily accessible for cleaning. § 1009.3.
Gravity grease interceptors: size by DFUs using Table 1014.3.6 or by actual flow (gpm × 30 min retention). Table values and example sizing are provided in the code. § 1014.3.6 and Table 1014.3.6.

Exceptions & special cases

Building traps: generally prohibited unless specifically required by the AHJ; where allowed they must have a cleanout and a relieving vent/fresh‑air intake on the inlet side (see § 1008.1).
Interceptors may omit a vent when the interceptor functions as a primary settling tank and discharges to a properly trapped and vented secondary interceptor (see § 902.1).
Deep‑seal traps are required in some processing plants (e.g., meat/poultry plants) and may be required where floor drains are regularly washed down — check § 1010.2 and related AGR sections.
The AHJ can require deeper trap seals than the standard 2–4 inches when conditions demand. § 1005.1.

Common mistakes (inspection / design traps & interceptors)

Installing traps that rely on movable parts (bladders, check valves) — these are prohibited. § 1004.2.
Allowing tailpieces to exceed 24 inches (causes poor trap action and siphoning). § 1001.2.
Using an undersized grease interceptor because DFUs were not counted correctly (use Table 1014.3.6 or flow‑based sizing). § 1014.3.6.
Failing to provide trap‑seal primers on infrequently used floor drains or making primers inaccessible for service. § 1007.1.
Double‑trapping fixtures (more than one trap in series) — the code forbids double traps. § 1004.1.

Worked example — kitchen grease interceptor sizing (from the code example)

Given the code example in the CPC (restaurant):

Fixtures: 3 floor drains @ 2 DFU each = 6 DFU; 1 mop sink = 3 DFU; 1 food prep sink = 3 DFU → Total = 12 DFU. Using Table 1014.3.6, that total corresponds to a 750‑gallon gravity grease interceptor in the code example. § 1014.3.6.

How this applies on a plan:

Count DFUs exactly as the code’s plumbing tables require, then pick the next interceptor size in Table 1014.3.6 or compute by actual max flow (gpm × 30 minutes) and round up to a code‑listed nominal volume. § 1014.3.6.

Related provisions (quick navigation)

§ 1001.2 — Where traps are required; tailpiece limit (24 in.).
§ 1002.1 — Trap protection by vent pipes; trap‑arm developed length limits (Table 1002.2).
§ 1003.1 — Trap materials and self‑scouring requirement.
§ 1004.1 / § 1004.2 — Prohibited trap types and movable parts prohibition.
§ 1005.1 — Trap seal depth limits (2”–4”).
§ 1007.1 – § 1007.2 — Trap‑seal protection and primer standards (ASSE/IAPMO).
§ 1008.1 — Building trap special rules.
§ 1009.1 – § 1009.7 — Interceptors (clarifiers), design, venting, location, maintenance.
§ 1014.3.6 and Table 1014.3.6 — Gravity grease interceptor sizing and example.
Definitions (T‑section) — § 222.0 (Tailpiece, Trap, Trap Seal, Trap Primer definitions).

Code references

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

CPC § 1323.13.3 Medium relevance — show source text
2, 1323.13.3| |1326.4 - 1326.10|1326.5 - 1326.11| |1505.6 - 1505.14|1505.5 - 1505.13| |Figure 1505.10|Figure 1505.9| |1506.6 - 1506.13|1506.5 - 1506.12| |1603.3 - 1603.4|1603.4 - 1603.5| |Table 1603.4|Table 1603.5| |1603.5 - 1603.19|1603.6 - 1603.20| |1603.20|1503.2.4| |L 402.9 - L 402.11|L 402.8 - L 402.10| |L 404.9 - L 404.12|L 404.8 - L 404.11| |L 411.5, L 411.6|L 411.2, L411.3| |L 411.7|L 411.4| |L 411.9 - L 411.12|L 411.5 - L 411.8|

xxii 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

RELATED PUBLICATIONS AND SERVICES

The Documents Listed are Not by this Reference Adopted by The State of California.

IAPMO provides a variety of other products which are useful for inspectors, building officials, architects, engineers,

manufacturers, contractors, plumbers, and apprentices.

IAPMO Headquarters Directory

4755 East Philadelphia Street, Ontario, California 91761-2816

Publication Order Desk Phone: 800-85-IAPMO

Publication Toll Free Fax: 877-85-CODES

E-mail: iapmo@iapmo.org

Website: www.iapmo.org

Free Code Question: 800-201-0335

Uniform Plumbing Code – 2024 Edition:

The Uniform Plumbing Code is the most widely adopted plumbing code in the world. The 2024 edition contains complete “turnkey” requirements for the installation and maintenance of plumbing systems, all in one easy to use book.

Uniform Plumbing Code Illustrated Training Manual:

The UPC Illustrated Training Manual is an excellent reference for anyone involved in the plumbing industry. It contains an extensive definitions section and several hundred comprehensive technical diagrams and illustrations. It serves as a textbook, and it also is useful as a valuable tool for explaining the intent and use of the Code.

Uniform Plumbing Code Study Guide:

This book is the perfect complement to the UPC Illustrated Training Manual. Alone, it constitutes a complete self-study course for learning the UPC. It has hundreds of questions, general practice exams, and plumbing math, pipe sizing exercises and fitting identification. A big help in getting you ready for a certification exam!

Guide to Important Code Questions to the Uniform Plumbing Code:

An excellent reference for learning and understanding plumbing code changes and identifies code changes between editions. It is a useful tool for preparing code change proposals.

Uniform Mechanical Code – 2024 Edition:

The Uniform Mechanical Code contains complete requirements for the installation and maintenance of heating, ventilating, cooking and refrigeration systems.

Uniform Mechanical Code Illustrated Training Manual:

Contains technical diagrams and illustrations that demonstrate the intent and use of the UMC. A great reference for everyone involved in Mechanical HVACR design and installation.

Uniform Mechanical Code Study Guide:
CPC § 101.2.2 Medium relevance — show source text
CFC—25: California Fire Code

101.2.2, 101.4.2, 301.3.1, 302.2, 307.1, 308.1, 802.2.1, 802.2.3, 803.2.3, 803.4.1.1, 803.4.1.2, 803.4.1.3, 803.4.1.4, 803.4.1.5, 803.4.1.6, Table 804.5.1.1(1), 904.1.5, 1011.6.1.1, 1303.1.2, 1305.2.8.1, 1305.2.14, 1305.2.14.1, 1401.2, 1501.1, 1501.5, 1502.1, 1502.1.1, 1502.2, 1502.3, 1504.1, 1507.1, 1507.2

CMC—25: California Mechanical Code

302.2, 702.7, 807.1, 902.1.1, 1008.1, 1305.2.7.1, 1305.2.8, 1305.2.8.1

CPC—25: California Plumbing Code

302.2, 408.1, 702.7, 1009.1, 1009.2, 1009.3, 1009.5, 1302.1.6, 1503.1

16-4 2025 CALIFORNIA EXISTING BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

REFERENCED STANDARDS

CRC—25: California Residential Code

101.2, 101.4.1, 104.3.1, 109.3.3, 109.3.10, 302.2, 307.1, 308.1, 401.3, 402.1, 405.2.6, 502.2, 502.3, 502.4, 503.2, 503.3, 503.11, 505.2, 505.3, 507.3, 701.3, 702.4, 702.5, 706.2, 708.1, 805.2, 806.4, 809.1, 906.2, 907.1, 1011.2.1, 1103.1, 1103.2, 1103.3, 1104.1, 1201.4, 1302.1.2, 1302.1.3, 1302.1.3, 1303.1.3, 1401.2, 1402.1, 1402.2, 1402.2.1, 1402.3, 1402.4, 1402.5, 1402.6

ICC 300—2023: ICC Standard on Bleachers, Folding and Telescopic Seating and Grandstands

301.1.1, 401.1.1, 1401.1.1

ICC A117.1—2017: Accessible and Usable Buildings and Facilities
CPC § 11.0 Medium relevance — show source text
11.0 - 1.11.11_|||X|||||||||||||||||||||| |1.13.0||||||||||||||||||||X||||| |Division II - Scope and
Administration||||||||||||||||||||||||| |101.0||||||||||X|X|X||X|X|||||||||| |102.0||||||||||X|X|X||X|X|||||||||| |103.0||||||||||X|X|X||X|X|||||||||| |104.2 Items 1 & 2||||X|X|||||||||||||||||||| |104.3.1||||||||||X|X|X||X|X|||||||||| |104.4.3.1|X|||||||||||||||||||||||| |105.0||||||||||X|X|X||X|X||||||||||

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

2 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

CHAPTER 1

ADMINISTRATION

DIVISION I

CALIFORNIA ADMINISTRATION

1.1.0 General.

1.1.1 Title. These regulations shall be known as the Califor- nia Plumbing Code, may be cited as such and will be referred to herein as “this code.” The California Plumbing Code is Part 5 of thirteen parts of the official compilation and publi- cation of the adoption, amendment, and repeal of plumbing regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption the 2024 Uniform Plumb- ing Code of the International Association of Plumbing and Mechanical Officials with necessary California amendments.

1.1.2 Purpose. The purpose of this code is to establish the minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, access to persons with disabilities, sanitation, adequate lighting and ventilation, and energy con- servation; safety to life and property from fire and other haz- ards attributed to the built environment; and to provide safety to fire fighters and emergency responders during emergency operations.

1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replace- ment, repair, equipment, use and occupancy, location, main- tenance, removal, and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures throughout the State of California.
CPC § 4.1 Medium relevance — show source text
- 100°F
  (16°C-38°C)|1 h|6 h|2 h|12 h|6 h|24 h| |40°F-60°F
  (4°C-16°C)|2 h|12 h|4 h|24 h|12 h|48 h| |10°F- 40°F
  (-12°C+4°C)|8 h|48 h|16 h|96 h|48 h|8 days| |*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|
2025 CALIFORNIA PLUMBING CODE 467

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

IS 33

FIGURE 1

LOCATION OF THRUST BLOCKS (STANDARD AND METRIC COMBINED) A COMPARISON OF THRUST-BLOCK AREAS (See Section 4.1)

468 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

IS 33

FIGURE 2

THRUST BLOCK BEARING AREA (See Section 5.2.2)

2025 CALIFORNIA PLUMBING CODE 469

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

IS 33

Uniform Plumbing Code References for Ductile Iron and PVC Pressure Building Supply and Exterior Cold-Water Piping

The following sections of the 2024 Uniform Plumbing Code apply to ductile iron and PVC pressure building supply and exterior cold-water piping.

Chapter 3 General Regulations

309.0 Workmanship

312.0 Protection of Piping, Materials, and Struc tures

313.0 Hangers, Supports, and Anchors

314.0 Trenching, Excavation, and Backfill

Chapter 6 Water Supply and Distribution

604.0 Materials (water piping)

Table 604.1 Materials for Building Supply and Water Distribution Piping and Fittings

605.4 Ductile Iron Pipe and Joints

605.12 PVC Plastic Pipe and Joints

605.16.2 Plastic Pipe to Other Materials

609.0 Installation, Testing, Unions, and Location

Abbreviations

IAPMO International Association of Plumbing and Mechanical Officials

UPC Uniform Plumbing Code published by IAPMO

AWWA American Water Works Association

CSA Canadian Standards Association

Applicable Standards.

ASME B16.4 Gray Iron Threaded Fittings Classes 125 and 250

ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120

ASTM D2241 Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)
CPC § 102.3 Medium relevance — show source text
1

CEBC—25: California Existing Building Code

102.3, 1011.5.2, 1103.1, 1104.18, 1105.5.2

CMC—25: California Mechanical Code

201.3, 308.3, 605.1, 605.2.1.1, 605.2.1.2, 605.2.1.3, 605.2.1.4, 605.2.1.5, 605.3, 605.4, 605.4.2.3, 605.4.2.5, 605.5.2, 605.7, 606.1, 606.2, 608.1, 608.3, 608.4, 608.5, 608.8, 608.9.1, 608.10, 608.17, 610.1.1, 903.2.11.4, 904.14, 907.3.1, 909.1, 909.10.2, 909.13.1, 910.4.7, 915.6.1, 1006.2.2.3, 1011.16, 1020.6.1, 1207.4.7, 1207.6.1, 1207.6.1.2.2, 1207.11.8, 2104.2.1, 2105.3, 2301.1, 2301.6, 2309.3.1.2, 2311.3.1, 2311.4.3, 2311.8.2, 2311.8.8, 2311.8.10, 2404.9, 2404.9.2, 2504.5, 2703.2.2, 2703.10.4, 2703.14, 2803.2, 2803.3, 3001.1, 3003.1, 3004.2, 3108.12.1, 3108.12.2, 3703.5, 3804.1.1.7, 3904.1, 3905.3, Table 5003.1.1(1), 5003.8.4.2, 5003.8.5.2, 5003.8.6.2, 5004.3.1, 5303.7.6, 5303.16.9, 5305.5, 5306.2.2, 5306.2.3, 5307.4.4, 5504.2.1.3, 5504.2.2.3, 5505.4.1.1, 5701.3, 5703.6.1, 5704.2.8.9, 5705.3.7.5.1, 5706.2, 5706.4.4, 6003.1.3, 6003.2.3.2, 6004.2.2.7, 6005.3.1, 6005.3.2, 6103.2.1.7

CPC—25: California Plumbing Code
CPC § 309.0 Medium relevance — show source text
2025 CALIFORNIA PLUMBING CODE 469

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

IS 33

Uniform Plumbing Code References for Ductile Iron and PVC Pressure Building Supply and Exterior Cold-Water Piping

The following sections of the 2024 Uniform Plumbing Code apply to ductile iron and PVC pressure building supply and exterior cold-water piping.

Chapter 3 General Regulations

309.0 Workmanship

312.0 Protection of Piping, Materials, and Struc tures

313.0 Hangers, Supports, and Anchors

314.0 Trenching, Excavation, and Backfill

Chapter 6 Water Supply and Distribution

604.0 Materials (water piping)

Table 604.1 Materials for Building Supply and Water Distribution Piping and Fittings

605.4 Ductile Iron Pipe and Joints

605.12 PVC Plastic Pipe and Joints

605.16.2 Plastic Pipe to Other Materials

609.0 Installation, Testing, Unions, and Location

Abbreviations

IAPMO International Association of Plumbing and Mechanical Officials

UPC Uniform Plumbing Code published by IAPMO

AWWA American Water Works Association

CSA Canadian Standards Association

Applicable Standards.

ASME B16.4 Gray Iron Threaded Fittings Classes 125 and 250

ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120

ASTM D2241 Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

ASTM D2466 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40

ASTM D2467 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80

ASTM F1970 Special Engineered Fittings, Appurtenances or Valves for use in Poly (Vinyl Chloride) (PVC) or Chlorinated Poly (Vinyl Chloride) (CPVC) Systems

AWWA C110 Ductile Iron and Gray-Iron Fittings

AWWA C111 Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings

AWWA C151 Ductile-Iron Pipe, Centrifugally Cast

AWWA C153 Ductile-Iron Compact Fitting

AWWA C900 Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 in. through 12 in. (100 mm through 300 mm)

AWWA C904 Crosslinked Polyethylene (PEX) Pressure Tubing, ½ in. through 3 In. (13 mm through 76 mm), for Water Service

AWWA C907 Injection-Molded Polyvinyl Chloride (PVC) Pressure Fittings, 4 In, through 12 in (100 mm through 300 mm) for Water, Wastewater and Reclaimed Water Service

IAPMO/

ANSI UPC-1 Uniform Plumbing Code

470 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
CPC § 1205.1 Medium relevance — show source text
1205.1 Authorized Personnel . . . . . . . . . .216

1205.2 Outlets . . . . . . . . . . . . . . . . . . . . .216

1206.0 Authority to Disconnect . . . . . . . .216

1206.1 Disconnection . . . . . . . . . . . . . . . .216

1206.2 Notice . . . . . . . . . . . . . . . . . . . . . .216

1206.3 Capped Outlets . . . . . . . . . . . . . . .216

1207.0 Temporary Use of Gas . . . . . . . . .216

1207.1 General . . . . . . . . . . . . . . . . . . . . .216

1208.0 Gas Piping System Design, Materials, and Components . . . . .216

1208.1 Installation of Piping System . . . .216

1208.2 Interconnections Supplying Separate Users . . . . . . . . . . . . . . .216

1208.3 Sizing of Gas Piping Systems . . .216

Table 1208.3.1 Approximate Gas Input for Typical Appliances . . . . . . . . . . . .217

1208.4 Maximum Operating Pressure in Buildings . . . . . . . . . . . . . . . . . .217

1208.5 Acceptable Piping Materials and Joining Methods . . . . . . . . . .217

Table 1208.5.8.2 Specifications for Threading Metallic Pipe . . . . . . . . . . . . . . . . .219

1208.6 Gas Meters . . . . . . . . . . . . . . . . . .220

1208.7 Gas Pressure Regulators . . . . . . .221

1208.8 Overpressure Protection Required . . . . . . . . . . . . . . . . . . . .221

1208.9 Overpressure Protection Devices . . . . . . . . . . . . . . . . . . . . .221

1208.10 Pressure Limitation

Requirements . . . . . . . . . . . . . . . .222

1208.11 Backpressure Protection . . . . . . .222

1208.12 Low-Pressure Protection . . . . . . .222

1208.13 Shutoff Valves . . . . . . . . . . . . . . .222

1208.14 Expansion and Flexibility . . . . . . .222

1208.15 Pressure Regulator and Pressure Control Venting . . . . . . .222

Table 1208.13 Manual Gas Valve Standards . . . .223

1209.0 Excess Flow Valve . . . . . . . . . . . .223

1209.1 General . . . . . . . . . . . . . . . . . . . . .223

1210.0 Gas Piping Installation . . . . . . . . .223

1210.1 Piping Underground . . . . . . . . . . .223

1210.2 CSST Piping Systems . . . . . . . . .225

1210.3 Installation of Aboveground Piping . . . . . . . . . . . . . . . . . . . . . .225
CPC § 18949.2 Medium relevance — show source text
Authority Cited – Health and Safety Code Sections 13143, 13108.5(a), and 18949.2(b) and (c); and Government Code Section 51189.

References – Health and Safety Code Sections 13143, Gov- ernment Code Sections 51176, 51177, 51178, and 51179; and Public Resources Code Sections 4201 through 4204.

1.11.2 Duties and Powers of the Enforcing Agency.

1.11.2.1 Enforcement.

1.11.2.1.1 The responsibility for enforcement of building standards adopted by the State Fire Mar- shal and published in the California Building Stan- dards Code relating to fire and panic safety and other regulations of the State Fire Marshal shall except as provided in Section 1.11.2.1.2 be as fol- lows:

1. The city, county, or city and county, with juris- diction in the area affected by the standard or regulation shall delegate the enforcement of the building standards relating to fire and panic safety and other regulations of the State Fire Marshal as they relate to Group R-3 occupan- cies, as described in Section 310.1 of Part 2 of the California Building Standards Code, to either of the following:

1.1. The chief of the fire authority of the city, county, or city, and county or an authorized rep- resentative.

1.2. The chief building official of the city, county, or city and county, or an authorized rep- resentative.

2. The chief of any city or county fire department or of any fire protection district, and authorized representatives, shall enforce within the juris- diction the building standards and other regu- lations of the State Fire Marshal, except those described in Item 1 or 4.

3. The State Fire Marshal shall have authority to enforce the building standards and other regu- lations of the State Fire Marshal in areas out- side of corporate cities and districts providing fire protection services.

4. The State Fire Marshal shall have authority to enforce the building standards and other regu- lations of the State Fire Marshal in corporate cities and districts providing fire-protection services on request of the chief fire official or the governing body.

5. Any fee charged pursuant to the enforcement authority of this section shall not exceed the estimated reasonable cost of providing the serv- ice for which the fee is charged pursuant to Sec- tion 66014 of the Government Code.

1.11.2.1.2 Pursuant to Health and Safety Code Sec- tion 13108, and except as otherwise provided in this section, building standards adopted by the State Fire Marshal published in the California Building Stan-

16 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

DIVISION I CALIFORNIA ADMINISTRATION

dards Code relating to fire and panic safety shall be enforced by the State Fire Marshal in all state- owned buildings, state-occupied buildings, and state _institutions throughout the state.
CPC § 1201.0 Medium relevance — show source text
1201.0 General . . . . . . . . . . . . . . . . . . . . .215

1201.1 Applicability . . . . . . . . . . . . . . . . . .215

1202.0 Coverage of Piping System . . . . .215

1202.1 General . . . . . . . . . . . . . . . . . . . . .215

1202.2 Piping System Requirements . . . .215

1202.3 Applications . . . . . . . . . . . . . . . . .215

1203.0 Inspection . . . . . . . . . . . . . . . . . . .215

1203.1 Inspection Notification . . . . . . . . .215

1203.2 Excavation . . . . . . . . . . . . . . . . . .215

1203.3 Type of Inspections . . . . . . . . . . .215

1203.4 Inspection Waived . . . . . . . . . . . .216

1204.0 Certificate of Inspection . . . . . . . .216

1204.1 Issuance . . . . . . . . . . . . . . . . . . . .216

1204.2 Gas Supplier . . . . . . . . . . . . . . . . .216

1204.3 Unlawful . . . . . . . . . . . . . . . . . . . .216

1205.0 Authority to Render Gas Service . . . . . . . . . . . . . . . . . . . . .216

1205.1 Authorized Personnel . . . . . . . . . .216

1205.2 Outlets . . . . . . . . . . . . . . . . . . . . .216

1206.0 Authority to Disconnect . . . . . . . .216

1206.1 Disconnection . . . . . . . . . . . . . . . .216

1206.2 Notice . . . . . . . . . . . . . . . . . . . . . .216

1206.3 Capped Outlets . . . . . . . . . . . . . . .216

1207.0 Temporary Use of Gas . . . . . . . . .216

1207.1 General . . . . . . . . . . . . . . . . . . . . .216

1208.0 Gas Piping System Design, Materials, and Components . . . . .216

1208.1 Installation of Piping System . . . .216

1208.2 Interconnections Supplying Separate Users . . . . . . . . . . . . . . .216

1208.3 Sizing of Gas Piping Systems . . .216

Table 1208.3.1 Approximate Gas Input for Typical Appliances . . . . . . . . . . . .217

1208.4 Maximum Operating Pressure in Buildings . . . . . . . . . . . . . . . . . .217

1208.5 Acceptable Piping Materials and Joining Methods . . . . . . . . . .217

Table 1208.5.8.2 Specifications for Threading Metallic Pipe . . . . . . . . . . . . . . . . .219
California Plumbing Code Medium relevance — show source text

18
38
50
59
69|349
250
242
229
217
206|202
166
160
150
142
134|0
20
47
62
73
84|540
377
367
351
337
322|307
249
241
228
217
206|0
33
62
81
94
107|776
531
519
499
481
464|430
346
337
321
308
295| |30|0
2
5
10
15
20
30|0
9
21
27
33
56
NA|100
81
77
70
64
58
NA|64
56
54
50
NA
NA
NA|0
13
28
37
44
53
73|213
166
160
150
141
132
113|128
112
108
102
96
90
NA|0
14
36
48
57
66
88|374
283
275
262
249
237
214|220
185
176
171
163
154
NA|0
18
45
59
70
80
104|587
432
421
405
389
374
346|336
280
273
261
249
237
219|0
27
58
77
90
102
131|853
613
600
580
560
542
507|475
394
385
371
357
343
321| |50|0
2
5
10
15
20
30|0
8
20
26
59
NA
NA|101
86
82
76
70
NA
NA|67
61
NA
NA
NA
NA
NA|0
11
27
35
42
50
69|216
183
177
168
158
149
131|134
122
119
114
NA
NA
NA|0
14
35
45
54
63
84|397
320
312
299
287
275
250|232
206
200
190
180
169
NA|0
15
43
56
66
76
99|633
497
487
471
455
440
410|363
314
308
298
288
278
259|0
California Plumbing Code Medium relevance — show source text

32
50
59|375
232
227
223|205
157
153
149|0
44
66
78|524
321
316
310|285
217
211
205| |8|0
2
5
8|0
12
23
28|84
57
53
49|50
40
38
35|0
16
32
39|165
109
103
98|94
75
71
66|0
25
42
51|276
178
171
164|155
120
115
109|0
28
53
64|415
263
255
247|235
180
173
165|0
42
70
84|583
365
356
347|320
247
237
227| |10|0
2
5
10|0
12
23
30|88
61
57
51|53
42
40
36|0
17
32
41|175
118
113
104|100
81
77
70|0
23
41
54|295
194
187
176|166
129
124
115|0
26
52
67|447
289
280
267|255
195
188
175|0
40
68
88|631
402
392
376|345
273
263
245| |15|0
2
5
10
15|0
11
22
29
35|94
69
65
59
53|58
48
45
41
37|0
15
30
40
48|191
136
130
121
112|112
93
87
82
76|0
20
39
51
61|327
226
219
206
195|187
150
142
135
128|0
22
49
64
76|502
339
330
315
301|285
225
217
208
198|0
38
64
84
98|716
475
463
445
429|390
316
300
288
275| |20|0
2
5
10
15
20|0
10
21
28
34
48|97
75
71
64
58
52|61
51
48
44
40
35|0
California Plumbing Code Medium relevance — show source text

18
45
59
70
80
104|587
432
421
405
389
374
346|336
280
273
261
249
237
219|0
27
58
77
90
102
131|853
613
600
580
560
542
507|475
394
385
371
357
343
321| |50|0
2
5
10
15
20
30|0
8
20
26
59
NA
NA|101
86
82
76
70
NA
NA|67
61
NA
NA
NA
NA
NA|0
11
27
35
42
50
69|216
183
177
168
158
149
131|134
122
119
114
NA
NA
NA|0
14
35
45
54
63
84|397
320
312
299
287
275
250|232
206
200
190
180
169
NA|0
15
43
56
66
76
99|633
497
487
471
455
440
410|363
314
308
298
288
278
259|0
22
55
73
85
97
123|932
715
702
681
662
642
605|518
445
438
426
413
401
376| |100|0
2
5
10
15
20
30
50|NA
NA
NA
NA
NA
NA
NA
NA|NA
NA
NA
NA
NA
NA
NA
NA|NA
NA
NA
NA
NA
NA
NA
NA|0
10
26
33
40
47
NA
NA|218
194
189
182
174
166
NA
NA|NA
NA
NA
NA
NA
NA
NA
NA|0
12
33
43
50
59
78
NA|407
354
347
335
321
311
290
NA|NA
NA
NA
NA
NA
NA
NA
NA|0
13
40
53
62
71
92
147|665
566
557
542
528
513
483
428|400
375
369
361
353
344
NA
NA|0
CPC § 2025 High relevance — show source text
The waste must be treated to prevent any damage to the piping or sewage treatment process. Waste receptors are sized and designed to prevent splashing and allow for peak discharge conditions.

Chapter 9 Vents.

Chapter 9 regulates the material, design, and installation of vents. A vent system is a pipe or pipes installed in a drainage system that provide a flow of air to and from the system to ventilate it, provide a circulation of air to eliminate trap siphonage, and reduce back-pressure and vacuum surge. In addition, vents provide the rapid and silent flow of waste without exposing occupants of the building to any sewer gases. Proper installation of vents is crucial, as a telltale sign that there is a problem in the drain and vent system is related to the elevation of the horizontal portion of the venting. Venting is not limited to sanitary drainage systems. Venting methods are applicable to other drainage systems such as those for chemical waste, graywater waste, and clear water waste. Sizing the venting system is directly tied to the design of the drainage system. For example, the velocities in the drainage system and its peak flow rates affect the diameters in the venting system. Where the vertical distance between a fixture outlet and trap is excessive, velocities in the entire drainage system will be greater than those in the vent sizing table. All venting methods in this chapter are categorized as either dry vents or wet vents. Vent stacks, stack vents, branch vents, island vents, relief vents, and individual vents are dry vents. Wet vents (horizontal or vertical), circuit vents, combination drain and vents are versions of “wet venting” in which the vent is wetted by drainage flow.

2025 CALIFORNIA PLUMBING CODE xv

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

FORMAT OF THE UNIFORM PLUMBING CODE

Chapter 10 Traps and Interceptors.

Chapter 10 regulates the material, design, and installation of traps, interceptors, and separators. Traps are required on drainage type plumbing fixtures and must be self-scouring without interior partitions. Interceptors, on the other hand, are designed to control what goes down a drain. Interceptors are used to keep harmful substances from entering the sanitary drainage system, such as grease, sand, oil and other materials. The retained materials need periodic removal to maintain efficiency and function of the separating device. The capacity of an interceptor is based on retention and flow rate. There are many types of interceptors that are used at beauty salons, hospitals, meat, fish or foul packaging, refineries, repair garages, gas stations, car washing facilities, various plants, factories, and processing sites. The designer of the building is responsible for locating interceptors with the expectation for the frequency of maintenance, ease of cleaning and floor space for equipment.

Chapter 11 Storm Drainage.

Chapter 11 regulates the removal of stormwater from roofs, yards, paved areas, and similar areas. The objective of storm drainage systems is to provide a conduit or channel through which runoff will be carried from a point of collection to a point of disposal; this protects the property and the public from the uncontrolled flow of runoff and ensures that drains and inlets are adequately sized to receive the volume of runoff that flows to the drains. For the purpose of system design, it’s necessary to specify the duration of a selected storm.
CPC § 1004.2 Medium relevance — show source text
1004.2 Movable Parts. Bladders, check valves or another type of devices with moveable parts shall be prohibited to serve as a trap.

1005.0 Trap Seals. 1005.1 General. Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm), except where a deeper seal is found necessary by the Authority Having Jurisdiction. Traps shall be set true with respect to their liquid seals and, where necessary, they shall be protected from freezing.

1006.0 Floor Drain Traps. 1006.1 General. Floor drains shall connect into a trap so constructed that it can be readily cleaned and of a size to serve efficiently the purpose for which it is intended. The drain inlet shall be so located that it is in full view. Where subject to the reverse flow of sewage or liquid waste, such drains shall be equipped with an approved backwater valve.

1007.0 Trap Seal Protection. 1007.1 General. Floor drain or similar traps directly connected to the drainage system and subject to infrequent use shall be protected with a trap seal primer, except where not deemed necessary for safety or sanitation by the Authority Having Jurisdiction. Trap seal primers shall be accessible for maintenance.

1007.2 Trap Seal Primers. Potable water supply trap seal primer valves shall comply with ASSE 1018. Drainage or electronic design type trap seal primer devices shall comply with ASSE 1044 or IAPMO PS 76.

1008.0 Building Traps. 1008.1 General. Building traps shall not be installed except where required by the Authority Having Jurisdiction. Each building trap where installed shall be provided with a cleanout and with a relieving vent or fresh-air intake on the inlet side of the trap, which needs not be larger than one-half the diameter of the drain to which it connects. Such relieving vent or fresh-air intake shall be carried above grade and terminate in a screened outlet located outside the building.

1009.0 Interceptors (Clarifiers) and Separators.

1009.1 Where Required. Interceptors (clarifiers) (including grease, oil, sand, solid interceptors, etc.) shall be required

by the Authority Having Jurisdiction where they are necessary for the proper handling of liquid wastes containing grease, flammable wastes, sand, solids, acid or alkaline substances, or other ingredients harmful to the building drainage system, the public or private sewer, or to public or private sewage disposal. A list of acceptable interceptor standards is referenced in Table 1009.1.

TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)
CPC § 1.11.0. Medium relevance — show source text
1 Exception 2_||||X|X|||||||||||||||||||| |1010.2|||||||||||||||||||X|||||| |1010.3|||||||||||||||||||X|||||| |1010.4|||||||||||||||||||X|||||| |1010.5|||||||||||||||||||X|||||| |1014.1A, B, C||||||||||X|X|X|X|X|X|||||||||| |1015.5||||||||||X|X|X|X|X|X|||||||||| |1015.6||||||||||X|X|X|X|X|X||||||||||

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

2025 CALIFORNIA PLUMBING CODE 193

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

194 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

CHAPTER 10

TRAPS AND INTERCEPTORS

1001.0 General.

1001.1 Applicability. This chapter shall govern the materials, design, and installation of traps and interceptors.

1001.2 Where Required. Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap. This section shall not apply to fixtures with integral traps. Not more than one trap shall be permitted on a trap arm. Food waste disposers installed with a set of restaurant, commercial, or industrial sinks shall be connected to a separate trap.

Each domestic clothes washer and each laundry sink shall be connected to a separate and independent trap, except that a trap serving a laundry sink shall also be permitted to receive the waste from a clothes washer set adjacent to it.

The vertical distance between a fixture outlet and the trap weir shall be as short as practicable, but in no case shall the tailpiece exceed 24 inches (610 mm) in length.

One trap shall be permitted to serve a set of not more than three single compartment sinks or laundry sinks of the same depth or three lavatories immediately adjacent to each other and in the same room where the waste outlets are not more than 30 inches (762 mm) apart, and the trap is centrally located where three compartments are installed.

1002.0 Traps Protected by Vent Pipes.

1002.1 Vent Pipes. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage, backpressure, and air circulation shall be assured throughout the drainage system using a vent pipe installed in accordance with the requirements of this code.
CPC § 1001.0 Medium relevance — show source text
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

CHAPTER 10

TRAPS AND INTERCEPTORS

1001.0 General.

1001.1 Applicability. This chapter shall govern the materials, design, and installation of traps and interceptors.

1001.2 Where Required. Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap. This section shall not apply to fixtures with integral traps. Not more than one trap shall be permitted on a trap arm. Food waste disposers installed with a set of restaurant, commercial, or industrial sinks shall be connected to a separate trap.

Each domestic clothes washer and each laundry sink shall be connected to a separate and independent trap, except that a trap serving a laundry sink shall also be permitted to receive the waste from a clothes washer set adjacent to it.

The vertical distance between a fixture outlet and the trap weir shall be as short as practicable, but in no case shall the tailpiece exceed 24 inches (610 mm) in length.

One trap shall be permitted to serve a set of not more than three single compartment sinks or laundry sinks of the same depth or three lavatories immediately adjacent to each other and in the same room where the waste outlets are not more than 30 inches (762 mm) apart, and the trap is centrally located where three compartments are installed.

1002.0 Traps Protected by Vent Pipes.

1002.1 Vent Pipes. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage, backpressure, and air circulation shall be assured throughout the drainage system using a vent pipe installed in accordance with the requirements of this code.

1002.2 Fixture Traps. Each fixture trap shall have a protecting vent so located that the developed length of the trap arm from the trap weir to the inner edge of the vent shall be within the distance given in Table 1002.2 but in no case less than two times the diameter of the trap arm. 1002.3 Change of Direction. A trap arm shall be permitted to change direction without the use of a cleanout where such change of direction does not exceed 90 degrees (1.57 rad). Horizontal changes in the direction of trap arms shall be in accordance with Section 706.3.

Exception: For trap arms, 3 inches (80 mm) in diameter and larger, the change of direction shall not exceed 135 degrees (2.36 rad) without the use of a cleanout. 1002.4 Vent Pipe Opening. The vent pipe opening from soil or waste pipe, except for water closets and similar fixtures, shall not be below the weir of the trap.

1003.0 Traps – Described. 1003.1 General Requirements. Each trap, except for traps within an interceptor or similar device shall be selfcleaning. Traps for bathtubs, showers, lavatories, sinks, laun

dry sinks, floor drains, urinals, drinking fountains, dental units, and similar fixtures shall be of standard design, weight and shall be of ABS, cast-brass, cast-iron, lead, PP, PVC, or other approved material. An exposed and readily accessible drawn-copper alloy tubing trap, not less than 17 B & S Gauge (0.045 inch) (1.143 mm), shall be permitted to be used on fixtures discharging domestic sewage.

Exception s :

CPC § 1007.2 Medium relevance — show source text

1007.2 Trap Seal Primers. Potable water supply trap seal primer valves shall comply with ASSE 1018. Drainage or electronic design type trap seal primer devices shall comply with ASSE 1044 or IAPMO PS 76.

1008.0 Building Traps. 1008.1 General. Building traps shall not be installed except where required by the Authority Having Jurisdiction. Each building trap where installed shall be provided with a cleanout and with a relieving vent or fresh-air intake on the inlet side of the trap, which needs not be larger than one-half the diameter of the drain to which it connects. Such relieving vent or fresh-air intake shall be carried above grade and terminate in a screened outlet located outside the building.

1009.0 Interceptors (Clarifiers) and Separators.

1009.1 Where Required. Interceptors (clarifiers) (including grease, oil, sand, solid interceptors, etc.) shall be required

by the Authority Having Jurisdiction where they are necessary for the proper handling of liquid wastes containing grease, flammable wastes, sand, solids, acid or alkaline substances, or other ingredients harmful to the building drainage system, the public or private sewer, or to public or private sewage disposal. A list of acceptable interceptor standards is referenced in Table 1009.1.

TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)

APPLICATION	STANDARD
Fats, Oil, Grease (FOG)	ASME A112.14.3, ASME A112.14.4, ASME A112.14.6, CSA B481, ANSI/CAN/IAPMO Z1001, PDI G-101, PDI G-102
Solid Waste	IAPMO IGC 167
Non-petroleum Oil	ASME A112.14.6, IAPMO PS 80, PDI G-102
Petroleum Oil	ASTM D6104, IAPMO IGC 183, IAPMO IGC 325

1009.2 Approval. The size, type, and location of each interceptor (clarifier) or separator shall be approved by the Authority Having Jurisdiction. Except where otherwise specifically permitted, no wastes other than those requiring treatment or separation shall be discharged into an interceptor (clarifier). 1009.3 Design. Interceptors (clarifiers) for sand and similar heavy solids shall be so designed and located as to be readily accessible for cleaning and shall have a water seal of not less than 6 inches (152 mm). 1009.4 Relief Vent. Interceptors (clarifiers) shall be so designed that they will not become air-bound where closed covers are used. Each interceptor (clarifier) shall be properly vented.

CPC § 25.4 Medium relevance — show source text
For SI units: 1 inch = 25.4 mm

Notes: 1 Maintain 1 ⁄ 4 inch per foot slope (20.8 mm/m). 2 The developed length between the trap of a water closet or similar fixture (measured from the face of the closet flange to the inner edge of the vent) and its vent shall not exceed 6 feet (1829 mm). 3 Horizontally wet vented bathtubs, showers and similar fixtures shall be limited to a maximum of 6 feet (1829 mm) for 1½ inch (40 mm) fixture drains and 8 feet (2438 mm) for 2 inch (50 mm) fixture drains, maintaining ¼ inch per foot slope (20.8 mm/m).

2025 CALIFORNIA PLUMBING CODE 195

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

TRAPS AND INTERCEPTORS

1004.0 Traps.

1004.1 Prohibited. No form of trap that depends for its seal upon the action of movable parts shall be used. No trap that has concealed interior partitions, except those of plastic, glass, or similar corrosion-resisting material, shall be used. “S” traps, bell traps, and crown-vented traps shall be prohibited. No fixture shall be double trapped. Drum and bottle traps shall be installed for special conditions. No trap shall be installed without a vent, except as otherwise provided in this code.

1004.2 Movable Parts. Bladders, check valves or another type of devices with moveable parts shall be prohibited to serve as a trap.

1005.0 Trap Seals. 1005.1 General. Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm), except where a deeper seal is found necessary by the Authority Having Jurisdiction. Traps shall be set true with respect to their liquid seals and, where necessary, they shall be protected from freezing.

1006.0 Floor Drain Traps. 1006.1 General. Floor drains shall connect into a trap so constructed that it can be readily cleaned and of a size to serve efficiently the purpose for which it is intended. The drain inlet shall be so located that it is in full view. Where subject to the reverse flow of sewage or liquid waste, such drains shall be equipped with an approved backwater valve.

1007.0 Trap Seal Protection. 1007.1 General. Floor drain or similar traps directly connected to the drainage system and subject to infrequent use shall be protected with a trap seal primer, except where not deemed necessary for safety or sanitation by the Authority Having Jurisdiction. Trap seal primers shall be accessible for maintenance.

1007.2 Trap Seal Primers. Potable water supply trap seal primer valves shall comply with ASSE 1018. Drainage or electronic design type trap seal primer devices shall comply with ASSE 1044 or IAPMO PS 76.
CPC § 1010.0 Medium relevance — show source text
1010.0 Slaughterhouses, Packing Establishments, etc.

1010.1 General. A fish, fowl, and animal slaughterhouse or establishment; a fish, fowl, and meat packing or curing establishment; a soap factory, tallow-rendering, fat-rendering, and a hide-curing establishment shall be connected to and shall drain or discharge into an approved grease interceptor (clarifier).

TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)

196 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

TRAPS AND INTERCEPTORS

1010.2 Meat and Poultry Processing Plants. [AGR]

1010.2.1 Drainage and Plumbing Systems. Drainage and plumbing systems shall meet the require- ments of Section 724.0.

1010.2.1.1 Each floor drain shall be equipped with a deep-seal trap.

1010.2.2 The plumbing shall be installed so as to prevent sewage from backing up and flooding the floor.

Exception: Floor drains in areas not regularly washed down will be acceptable with deep-seal traps, provided that such drains are connected to secondary drainage systems discharging into a safe sink or basin (air gap) that is properly trapped and vented, and that such drains accomplish the objectives and intent of this section.

1010.2.3 Interceptor traps which are connected with the sewer system shall not be near any edible products department or in any area where products are unloaded from or loaded into vehicles. To facilitate cleaning, such traps shall have inclined bottoms and be provided with suitable covers.

1010.3 Collection Centers and Facilities. [AGR] All drains shall be properly installed with adequate deep-sealed traps of the conventional “P,” “U” or “S” type and vents.

1010.4 Horse Meat and Pet Food Establishments.

[AGR] There shall be an efficient drainage and plumbing system for the establishment and premises. All drains and gut- ters shall be installed with traps and vents approved by the Department.

1010.5 Draining and Plumbing. [AGR] There shall be an efficient drainage and plumbing system for the plant and premises.

1010.5.1 Drainage and Gutters. All drains and gut- ters shall be properly installed with approved traps and vents. The drainage and plumbing system must permit the quick runoff of all water from plant buildings, and of surface water around the plant on the premises, and all such water shall be disposed of in such a manner as to prevent a nuisance or health hazard.

CPC § 1014.3.7 Medium relevance — show source text

1014.3.7 Abandoned Gravity Grease Intercep- tors. Abandoned grease interceptors shall be pumped and filled as required for abandoned sewers and sewage disposal facilities in Section 722.0.

DRAINAGE FIXTURE UNITS1, 3 (DFUs)	INTERCEPTOR VOLUME2 (gallons)
8	500
21	750
35	1000
90	1250
172	1500
216	2000
307	2500
342	3000
428	4000
576	5000
720	7500
2112	10 000
2640	15 000

For SI units: 1 gallon = 3.785 L

Notes: 1 The maximum allowable DFUs plumbed to the kitchen drain lines that will be connected to the grease interceptor. 2 This size is based on DFUs, the pipe size from this code; Table 703.2; Useful Tables for flow in half-full pipes (ref: Mohinder Nayyar Piping Handbook, 3rd Edition, 1992). Based on 30-minute retention time (ref.: George Tchobanoglous and Metcalf & Eddy. Wastewater Engineering Treatment, Disposal, and Reuse, 3rd Ed. 1991 & Ronald Crites and George Tchobanoglous. Small and Decentralized Wastewater Management Systems, 1998). Rounded up to nominal interceptor volume. 3 Where the flow rate of directly connected fixture(s) or appliance(s) have no assigned DFU values, the additional grease interceptor volume shall be based on the known flow rate (gpm) (L/s) multiplied by 30 minutes.

EXAMPLE 1014.3.6

GRAVITY GREASE INTERCEPTOR SIZING EXAMPLE

Given: A restaurant with the following fixtures and equip ment.

One food preparation sink; three-floor drains - one in the food prep area, one in the grill area, and one receiving the indirect waste from the ice machine and a mop sink.

Kitchen Drain Line DFU Count (from Table 702.1):

3 floor drains at 2 DFUs each = 6 DFUs

Mop sink at 3 DFUs each = 3 DFUs

Food prep sink at 3 DFUs each = 3 DFUs

Total = 12 DFUs

Using Table 1014.3.6, the grease interceptor will be sized at 750 gallons (2389 L).

1015.0 FOG (Fats, Oils, and Greases) Disposal Sys- tem.

1015.1 Purpose. The purpose of this section is to provide the necessary criteria for the sizing, application, and installation of FOG disposal systems designated as a pretreatment or discharge water quality compliance strategy.

TABLE 1014.3.6

GRAVITY GREASE INTERCEPTOR SIZING

2025 CALIFORNIA PLUMBING CODE 199

TRAPS AND INTERCEPTORS

CPC § 1009.1 Medium relevance — show source text

TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)

APPLICATION	STANDARD
Fats, Oil, Grease (FOG)	ASME A112.14.3, ASME A112.14.4, ASME A112.14.6, CSA B481, ANSI/CAN/IAPMO Z1001, PDI G-101, PDI G-102
Solid Waste	IAPMO IGC 167
Non-petroleum Oil	ASME A112.14.6, IAPMO PS 80, PDI G-102
Petroleum Oil	ASTM D6104, IAPMO IGC 183, IAPMO IGC 325

1009.5 Location. Each interceptor (clarifier) cover shall be readily accessible for servicing and maintaining the interceptor (clarifier) in working and operating condition. The use of ladders or the removal of bulky equipment to service interceptors (clarifiers) shall constitute a violation of accessibility. Location of interceptors (clarifiers) shall be shown on the approved building plan. 1009.6 Maintenance of Interceptors. Interceptors shall be maintained in efficient operating condition by periodic removal of accumulated grease, scum, oil, or other floating substances and solids deposited in the interceptor. 1009.7 Discharge. The waste pipe from oil and sand interceptors shall discharge as approved by the Authority Having Jurisdiction.

1010.0 Slaughterhouses, Packing Establishments, etc.

1010.1 General. A fish, fowl, and animal slaughterhouse or establishment; a fish, fowl, and meat packing or curing establishment; a soap factory, tallow-rendering, fat-rendering, and a hide-curing establishment shall be connected to and shall drain or discharge into an approved grease interceptor (clarifier).

TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)

196 2025 CALIFORNIA PLUMBING CODE

TRAPS AND INTERCEPTORS

1010.2 Meat and Poultry Processing Plants. [AGR]

1010.2.1 Drainage and Plumbing Systems. Drainage and plumbing systems shall meet the require- ments of Section 724.0.

1010.2.1.1 Each floor drain shall be equipped with a deep-seal trap.

CPC § 1.1 Medium relevance — show source text
1(2)_||||X||||||||||||||||||||| |903.1.1||||X|X|||||||||||||||||||| |903.1.2||||X||||||||||||||||||||| |903.1.3||||||||||X||X|X|X|X|||||||||| |906.2.1||||||||||X|X|X|X|X|X||||||||||

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

2025 CALIFORNIA PLUMBING CODE 187

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

188 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

CHAPTER 9

VENTS

901.0 General.

901.1 Applicability. This chapter shall govern the materials, design, and installation of plumbing vent systems. 901.2 Vents Required. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage and backpressure, and air circulation shall be ensured throughout all parts of the drainage system by means of vent pipes installed in accordance with the requirements of this chapter and as otherwise required by this code. 901.3 Trap Seal Protection. The vent system shall be designed to prevent a trap seal from being exposed to a pressure differential that exceeds 1 inch water column (0.24 kPa) on the outlet side of the trap.

902.0 Vents Not Required.

902.1 Interceptor. Vent piping shall be permitted to be omitted on an interceptor where such interceptor acts as a primary settling tank and discharges through a horizontal indirect waste pipe into a secondary interceptor. The second interceptor shall be properly trapped and vented. 902.2 Bars, Soda Fountains, and Counter. Traps serving sinks that are part of the equipment of bars, soda fountains, and counters need not be vented where the location and construction of such bars, soda fountains, and counters are such as to make it impossible to do so. Where such conditions exist, said sinks shall discharge using approved indirect waste pipes into a floor sink or other approved type of recep tor.

903.0 Materials.

903.1 Applicable Standards. Vent pipe and fittings shall comply with the applicable standards referenced in Table 701.2, except that:

(1) No galvanized steel or 304 stainless steel pipe shall be installed underground and shall be not less than 6 inches (152 mm) aboveground.

CPC § 1014.3.4 Medium relevance — show source text

1014.3.4 Location. Each grease interceptor shall be so installed and connected that it shall be easily accessible for inspection, cleaning, and removal of the intercepted grease. A gravity grease interceptor that complies with ANSI/CAN/IAPMO Z1001 shall not be installed in a

building where food is handled. Location of the grease interceptor shall meet the approval of the Authority Having Jurisdiction.

1014.3.4.1 Interceptors. Interceptors shall be placed as close as practical to the fixtures they serve.

1014.3.4.2 Business Establishment. Each

business establishment for which a gravity grease interceptor is required shall have an interceptor which shall serve that establishment unless other wise approved by the Authority Having Jurisdiction.

1014.3.4.3 Access. Each gravity grease interceptor shall be located to be readily accessible to the equipment required for maintenance.

1014.3.5 Construction Requirements. Gravity grease interceptors shall be designed to remove grease from effluent and shall be sized in accordance with this

section. Gravity grease interceptors shall also be designed to retain grease until accumulations can be removed by pumping the interceptor. When provided, a sample box shall be located at the outlet end of gravity grease interceptors so that the Authority Having Jurisdiction can periodically sample effluent quality.

1014.3.6 Sizing Criteria. The volume of the interceptor shall be determined by using Table 1014.3.6. Where drainage fixture units (DFUs) are not known, the interceptor shall be sized based on the maximum DFUs allowed for the pipe size connected to the inlet of the interceptor. Refer to Table 703.2, Drainage Piping, Horizontal.

1014.3.7 Abandoned Gravity Grease Intercep- tors. Abandoned grease interceptors shall be pumped and filled as required for abandoned sewers and sewage disposal facilities in Section 722.0.

DRAINAGE FIXTURE UNITS1, 3 (DFUs)	INTERCEPTOR VOLUME2 (gallons)
8	500
21	750
35	1000
90	1250
172	1500
216	2000
307	2500
342	3000
428	4000
576	5000
720	7500
2112	10 000
2640	15 000

For SI units: 1 gallon = 3.785 L

CPC § 901.1 Medium relevance — show source text
901.1 Applicability. This chapter shall govern the materials, design, and installation of plumbing vent systems. 901.2 Vents Required. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage and backpressure, and air circulation shall be ensured throughout all parts of the drainage system by means of vent pipes installed in accordance with the requirements of this chapter and as otherwise required by this code. 901.3 Trap Seal Protection. The vent system shall be designed to prevent a trap seal from being exposed to a pressure differential that exceeds 1 inch water column (0.24 kPa) on the outlet side of the trap.

902.0 Vents Not Required.

902.1 Interceptor. Vent piping shall be permitted to be omitted on an interceptor where such interceptor acts as a primary settling tank and discharges through a horizontal indirect waste pipe into a secondary interceptor. The second interceptor shall be properly trapped and vented. 902.2 Bars, Soda Fountains, and Counter. Traps serving sinks that are part of the equipment of bars, soda fountains, and counters need not be vented where the location and construction of such bars, soda fountains, and counters are such as to make it impossible to do so. Where such conditions exist, said sinks shall discharge using approved indirect waste pipes into a floor sink or other approved type of recep tor.

903.0 Materials.

903.1 Applicable Standards. Vent pipe and fittings shall comply with the applicable standards referenced in Table 701.2, except that:

(1) No galvanized steel or 304 stainless steel pipe shall be installed underground and shall be not less than 6 inches (152 mm) aboveground.

(2) ABS and PVC DWV piping installations shall be in accordance with the firestop protection requirements in the California Building Code . Except for individual single-family dwelling units, materials exposed within ducts or plenums shall have a flame-spread index of not more than 25 and a smoke-developed index of not more than 50 where tested in accordance with ASTM E84 or UL 723. Plastic piping installed in plenums shall be tested in accordance with all requirements of ASTM E84 or UL 723. Mounting methods, supports and sample sizes of materials for testing that are not specified in ASTM E84 or UL 723 shall be prohibited.

903.1.1 [HCD 1 & HCD 2] ABS or PVC installations are limited to not more than two stories of areas of resi- dential accommodation.

903.1.2 [HCD 1] All malleable iron vents shall be gal- vanized.

903.1.3 [OSHPD 1, 2, 3, 4 & 5] ABS and PVC instal- lations are not allowed.

903.2 Use of Copper or Copper Alloy Tubing. Copper or copper alloy tube for underground drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV. 903.2.1 Aboveground. Copper or copper alloy tube for aboveground drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV. 903.2.2 Prohibited Use. Copper or copper alloy tube shall not be used for chemical or industrial wastes as

defined in Section 811.0.
CPC § 222.0 Medium relevance — show source text
222.0 – T –

T Rating. The time period that the penetration firestop system, including the penetrating item, limits the maximum temperature rise of 325°F (181°C) above its initial temperature through the penetration on the nonfire side, where tested in accordance with ASTM E814 or UL 1479.

Tailpiece. The pipe or tubing that connects the outlet of a plumbing fixture to a trap. Testing Agency. [HCD 1] See “Approved Testing Agency”. Thermostatic (Temperature Control) Valve. A mixing valve that senses outlet temperature and compensates for fluctuations in incoming hot or cold water temperatures. Toilet. [OSHPD 1, 2, 3, 4 & 5] A fixture within a toilet room which is used for defecation or urination. Toilet Facility. A room or space containing not less than one lavatory and one water closet.

Toilet Room. [OSHPD 1, 2, 3, 4 & 5] A room within or on the premises containing water closets, urinals, and other required facilities. Transition Gas Riser. A listed or approved section or sections of pipe and fittings used to convey fuel gas and installed in a gas piping system to provide a transition from belowground to aboveground.

Trap. A fitting or device so designed and constructed as to provide, where properly vented, a liquid seal that will prevent the back passage of air without materially affecting the flow of sewage or wastewater through it.

Trap Arm. Those portions of a fixture drain between a trap and the vent.

Trap Primer. A device and system of piping that maintains a water seal in a remote trap. Trap Seal. The vertical distance between the crown weir and the top dip of the trap. Crown Weir (Trap Weir). The lowest point in the cross-section of the horizontal waterway at the exit of the trap. Top Dip (of the trap). The highest point in the internal cross-section of the trap at the lowest part of the bend (inverted siphon). By contrast, the bottom dip is the lowest point in the internal cross-section. Treated Gray Water. [BSC-CG & HCD 1] Nonpotable water meeting the definition of “gray water” collected and treated on-site suitable for direct beneficial use.

223.0 – U –

UPC. [HCD 1] “UPC” is the latest edition of the Uniform Plumbing Code, published by the International Association of Plumbing and Mechanical Officials. Unsanitary. See Insanitary.

User Outlet. See Station Outlet.

2025 CALIFORNIA PLUMBING CODE 43

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

DEFINITIONS

224.0 – V –

Vacuum. A pressure less than that exerted by the atmosphere.

Vacuum Breaker. See Backflow Preventer.
CPC § 1954.202 Medium relevance — show source text
Storm Drain. See Building Drain (Storm).

Storm Sewer. A sewer used for conveying rainwater, surface water, condensate, cooling water, or similar liquid

wastes.

Submeter. [HCD 1] A secondary device beyond a meter that measures water consumption of an individual rental unit within a multiunit residential structure or mixed-use residential and

commercial structure. (See Civil Code Section 1954.202(g) and Water Code Section 517 for additional details.)

Subsoil Drain. A drain that collects subsurface or seepage water and conveys it to a place of disposal.

Subsoil Irrigation Field. Gray water irrigation field installed in a trench within the layer of soil below the topsoil. This system is typically used for irrigation of deep rooted plants.

Subsurface Irrigation Field. Gray water irrigation field installed below finished grade within the topsoil.

Sump. An approved tank or pit that receives sewage or liquid waste and which is located below the normal grade of the gravity system and which must be emptied by mechanical

means.

Supports. Supports, hangers, and anchors are devices for properly supporting and securing pipe, fixtures, and equip ment.

Surge Tank. A reservoir to modify the fluctuation in flow rates to allow for uniform distribution of gray water to the points of irrigation.

222.0 – T –

T Rating. The time period that the penetration firestop system, including the penetrating item, limits the maximum temperature rise of 325°F (181°C) above its initial temperature through the penetration on the nonfire side, where tested in accordance with ASTM E814 or UL 1479.

Tailpiece. The pipe or tubing that connects the outlet of a plumbing fixture to a trap. Testing Agency. [HCD 1] See “Approved Testing Agency”. Thermostatic (Temperature Control) Valve. A mixing valve that senses outlet temperature and compensates for fluctuations in incoming hot or cold water temperatures. Toilet. [OSHPD 1, 2, 3, 4 & 5] A fixture within a toilet room which is used for defecation or urination. Toilet Facility. A room or space containing not less than one lavatory and one water closet.

Toilet Room. [OSHPD 1, 2, 3, 4 & 5] A room within or on the premises containing water closets, urinals, and other required facilities. Transition Gas Riser. A listed or approved section or sections of pipe and fittings used to convey fuel gas and installed in a gas piping system to provide a transition from belowground to aboveground.

Trap. A fitting or device so designed and constructed as to provide, where properly vented, a liquid seal that will prevent the back passage of air without materially affecting the flow of sewage or wastewater through it.

Trap Arm. Those portions of a fixture drain between a trap and the vent.
CPC § 1014.2.1. Medium relevance — show source text
(2) External flow control, without air intake (vent), directly connected.

(3) Without external flow control, directly connected.

(4) Without external flow control, indirectly connected.

These interceptors comply with the requirements of Table 1014.2.1. Hydromechanical grease interceptors are generally installed inside.

211.0 – I –

Indirect-Fired Water Heater. A water heater consisting of a storage tank equipped with an internal or external heat exchanger used to transfer heat from an external source to heat potable water. The storage tank either contains heated potable water or water supplied from an external source, such as a boiler.

Indirect Waste Pipe. A pipe that does not connect directly to the drainage system but conveys liquid wastes by discharging into a plumbing fixture, interceptor, or receptacle that is directly connected to the drainage system.

Individual Vent. A pipe installed to vent a fixture trap, and that connects with the vent system above the fixture served or terminates in the open air.

Industrial Waste. Liquid or water-borne waste from industrial or commercial processes, except domestic sewage.

Insanitary. A condition that is contrary to sanitary principles or is injurious to health.

Conditions to which “insanitary” shall apply include the following:

(1) A trap that does not maintain a proper trap seal.

(2) An opening in a drainage system, except where lawful that is not provided with an approved liquid-sealed trap.

(3) A plumbing fixture or other waste discharging receptor or device that is not supplied with water sufficient to flush and maintain the fixture or receptor in a clean condition.

(4) A defective fixture, trap, pipe, or fitting.

(5) A trap, except where in this code exempted, directly connected to a drainage system, the seal of which is not protected against siphonage and backpressure by a vent pipe.

(6) A connection, cross-connection, construction, or condition, temporary or permanent that would permit or make possible by any means whatsoever for an unapproved foreign matter to enter a water distribution system used for domestic purposes.

(7) The preceding enumeration of conditions to which the term “insanitary” shall apply, shall not preclude the application of that term to conditions that are, in fact, insanitary.

2025 CALIFORNIA PLUMBING CODE 37

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

DEFINITIONS

that maintains a periodic inspection program of production of labeled products, installations, equipment, or materials and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.

Lavatories in Sets. Two or three lavatories that are served by one trap. Lavatory. [HCD 1 & HCD 2] “Lavatory” shall mean a plumbing fixture used for washing the hands, arms, face and head.

Leader. An exterior vertical drainage pipe for conveying storm water from roof or gutter drains. See Downspout. _**Limited-Density Owner-Built Rural Dwelling.
CPC § 2-23 Medium relevance — show source text
[RB] TERMITE-RESISTANT MATERIAL. Pressure-preservative-treated wood in accordance with the AWPA standards in Section R304.1, naturally durable termite-resistant wood, steel, concrete, masonry or other approved material.

TESTING AGENCY. An agency approved by the department as qualified and equipped for testing of products, materials, equipment and installations in accordance with nationally recognized standards. For additional information, see Health and Safety Code Section 17920(m).

[MP] THIRD-PARTY CERTIFICATION AGENCY. An approved agency operating a product or material certification system that incorporates initial product testing, assessment and surveillance of a manufacturer’s quality control system.

[MP] THIRD-PARTY CERTIFIED. Certification obtained by the manufacturer indicating that the function and performance characteristics of a product or material have been determined by testing and ongoing surveillance by an approved third-party certification agency. Assertion of certification is in the form of identification in accordance with the requirements of the third-party certification agency.

TODDLER. Any child between 18 months and 36 months of age.

[RB] TOWNHOUSE. A building that contains three or more attached townhouse units.

2025 CALIFORNIA RESIDENTIAL CODE 2-23

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

�

�

�

�

�

�

�

�

�

�

�

DEFINITIONS

[RB] TOWNHOUSE UNIT. A single-family dwelling unit in a townhouse that extends from foundation to roof and that has a yard or public way on not less than two sides.

[MP] TRAP. A fitting, either separate or built into a fixture, that provides a liquid seal to prevent the emission of sewer gases without materially affecting the flow of sewage or wastewater through it.

[MP] TRAP ARM. That portion of a fixture drain between a trap weir and the vent fitting.

[MP] TRAP PRIMER. A device or system of piping to maintain a water seal in a trap, typically installed where infrequent use of the trap would result in evaporation of the trap seal, such as floor drains.

[MP] TRAP SEAL. The trap seal is the maximum vertical depth of liquid that a trap will retain, measured between the crown weir and the top of the dip of the trap.

[RB] TRIM. Picture molds, chair rails, baseboards, handrails, door and window frames, and similar decorative or protective materials used in fixed applications.

[RB] TRUSS DESIGN DRAWING. The graphic depiction of an individual truss, that describes the design and physical characteristics of the truss.

[RB] TUBULAR DAYLIGHTING DEVICE (TDD). A nonoperable fenestration unit primarily designed to transmit daylight from a roof surface to an interior ceiling via a tubular conduit. The basic unit consists of an exterior glazed weathering surface, a light-transmitting tube with a reflective interior surface, and an interior-sealing device such as a translucent ceiling panel. The unit may be factory assembled, or field assembled from a manufactured kit.

[MP] TYPE L VENT. A listed and labeled vent conforming to UL 641 for venting oil-burning appliances listed for use with Type L vents or with gas appliances listed for use with Type B vents.
CPC § 2.9 Medium relevance — show source text
[MP] TRAP. A fitting, either separate or built into a fixture, that provides a liquid seal to prevent the emission of sewer gases without materially affecting the flow of sewage or wastewater through it.

[MP] TRAP ARM. That portion of a fixture drain between a trap weir and the vent fitting.

[MP] TRAP PRIMER. A device or system of piping to maintain a water seal in a trap, typically installed where infrequent use of the trap would result in evaporation of the trap seal, such as floor drains.

[MP] TRAP SEAL. The trap seal is the maximum vertical depth of liquid that a trap will retain, measured between the crown weir and the top of the dip of the trap.

[RB] TRIM. Picture molds, chair rails, baseboards, handrails, door and window frames, and similar decorative or protective materials used in fixed applications.

[RB] TRUSS DESIGN DRAWING. The graphic depiction of an individual truss, that describes the design and physical characteristics of the truss.

[RB] TUBULAR DAYLIGHTING DEVICE (TDD). A nonoperable fenestration unit primarily designed to transmit daylight from a roof surface to an interior ceiling via a tubular conduit. The basic unit consists of an exterior glazed weathering surface, a light-transmitting tube with a reflective interior surface, and an interior-sealing device such as a translucent ceiling panel. The unit may be factory assembled, or field assembled from a manufactured kit.

[MP] TYPE L VENT. A listed and labeled vent conforming to UL 641 for venting oil-burning appliances listed for use with Type L vents or with gas appliances listed for use with Type B vents.

[RB] TYPE X. A type of gypsum panel product with special core additives to increase the fire resistance as specified by the applicable standards listed in Section R702.3 (see the definition of “Gypsum panel product”).

[RB] UNDERLAYMENT. One or more layers of felt, sheathing paper, nonbituminous saturated felt, or other approved material over which a roof covering, with a slope of 2 units vertical in 12 units horizontal (17-percent slope) or greater, is applied.

[MP] VACUUM BREAKER. A device that prevents back-siphonage of water by admitting atmospheric pressure through ports to the discharge side of the device.

[RB] VAPOR DIFFUSION PORT. An assembly constructed or installed within a roof assembly at an opening in the roof deck to convey water vapor from an unvented attic to the outside atmosphere.

[RB] VAPOR PERMEABLE. The property of having a moisture vapor permeance rating of 5 perms (2.9 × 10 [-10] kg/Pa × s × m [2] ) or greater, where tested in accordance with Procedure A or Procedure B of ASTM E96. A vapor permeable material permits the passage of moisture vapor.

[RB] VAPOR RETARDER CLASS. A measure of the ability of a material or assembly to limit the amount of moisture that passes through that material or assembly. Vapor retarder class shall be defined using the desiccant method with Procedure A of ASTM E96 as follows:

Class I: ≤ 0.1 perm rating

Class II: > 0.1 to ≤ 1.0 perm rating

Class III: > 1.0 to ≤ 10 perm rating
CPC § 101.3 Medium relevance — show source text
Combination waste and vent systems are intended primarily for extensive floor or shower drain installations where separate venting is not practical, for floor sinks in markets, demonstration or work tables in school buildings, or for similar applications where the fixtures are not adjacent to walls or partitions. Due to its oversize characteristics, such a waste system is not self-scouring and, consequently, care shall be exercised as to the type of fixtures connected to it and the location of cleanouts. Given its grease-producing potential, restaurant kitchen equipment shall not be connected to a combination waste and vent system.

B 101.3 Caution. Caution shall be exercised to exclude appurtenances delivering large quantities or surges of water (such as pumps, sand interceptors, etc.) from combination waste and vent systems so that adequate venting will be maintained. Small fixtures with a waste-producing potential of less than 7 [1] ⁄ 2 gallons per minute (gpm) (0.47 L/s) shall be permitted to be safely assigned a loading value of one unit. Long runs shall be laid at the minimum permissible slope to keep tailpieces as short as possible. Tailpieces shall not exceed 2 feet (610 mm) in length, which shall necessitate slopes up to 45 degrees (0.79 rad) (see definition of horizontal pipe) on some branches.

B 101.4 Pneumatics. It is essential that the pneumatics of such a system be properly engineered, as the air pressure within the line shall at all times balance that of outside atmosphere to prevent either trap seal loss or air locking between traps. Long mains shall be provided with additional relief vents located at intervals not exceeding 100 feet (30 480 mm). Each such relief vent shall equal not less than one-half of the inside cross-sectional area of the drainpipe served.

B 101.5 Trap Sizes. Trap sizes are required to be equivalent to the branches they serve (two pipe sizes larger than normal), and tailpieces between fixtures or floor drains and such traps shall be reduced to normal size.

B 101.6 Layout Drawings. Duplicate layout drawings of each such proposed piping system shall be presented to the Authority Having Jurisdiction and approval obtained before an installation is made. Complicated layouts shall be checked by qualified personnel. B 101.6.1 Example of Sizing. A floor drain normally requires a 2 inch (50 mm) trap and waste. On a combination waste and vent system, both trap and waste shall be increased two pipe sizes (through 2 [1] ⁄ 2 inches and 3 inches) (65 mm and 80 mm), which would make the trap 3 inches (80 mm). Pipe sizes recognized for this purpose are 2 inches, 2 [1] ⁄ 2 inches, 3 inches, 3 [1] ⁄ 2 inches, 4 inches, 4 [1] ⁄ 2 inches, 5 inches, 6 inches, etc. (50 mm, 65 mm, 80 mm, 90 mm, 100 mm, 115 mm, 125 mm, 150 mm, etc.). The tailpiece between the floor drain and its trap shall be 2 inches (50 mm) (or normal size) to ensure that the amount of wastewater entering the trap partially fills the waste branch.
CPC § 807.2 Medium relevance — show source text
807.2 Undiluted Condensate Waste. Where undiluted condensate waste from a fuel-burning condensing appliance is discharged into the drainage system, the material in the drainage system shall be cast-iron, galvanized iron, plastic, or other materials approved for this use.

Exceptions:

(1) Where the above condensate is discharged to an exposed fixture tailpiece and trap, such tailpiece and trap shall be permitted to be a copper alloy.

(2) Materials approved in Section 701.0 shall be permitted to be used where data is provided that the condensate waste is adequately diluted.

807.3 Domestic Dishwashing Machine. No domestic dishwashing machine shall be directly connected to a drainage system or food waste disposer without the use of an approved dishwasher air gap fitting on the discharge side of the dishwashing machine. Listed dishwasher air gap fittings shall be installed with the flood-level (FL) marking at or above the flood level of the sink or drainboard, whichever is higher.

808.0 Cooling Water.

808.1 General. Where permitted by the Authority Having Jurisdiction, clean running water used exclusively as a cooling medium in an appliance, device, or apparatus shall be permitted to discharge into the drainage system through the inlet side of a fixture trap in the event that a suitable fixture is not available to receive such discharge. Such trap connection shall be by means of a pipe connected to the inlet side of an approved fixture trap, the upper end terminating in a funnelshaped receptacle set adjacent, and not less than 6 inches (152 mm) above the overflow rim of the fixture.

809.0 Drinking Fountains.

809.1 General. Drinking fountains shall be permitted to be installed with indirect wastes through an air break.

810.0 Steam and Hot Water Drainage Condensers and Sumps.

810.1 High-Temperature Discharge. No steam pipe shall be directly connected to plumbing or drainage system, nor shall water having a temperature above 140°F (60°C) be discharged under pressure directly into a drainage system. Pipes from boilers shall discharge by means of indirect waste piping as determined by the Authority Having Jurisdiction or the boiler manufacturer’s recommendations. Such pipes shall be permitted to be indirectly connected by discharging into an open or closed condenser or an intercepting sump of an approved type that will prevent the entrance of steam or such water under pressure into the drainage system. Closed condensers or sumps shall be provided with a vent that shall be taken off the top and extended separately, full size above the roof. Condensers and sumps shall be properly trapped at the outlet with a deep seal trap extending to within 6 inches (152 mm) of the bottom of the tank. The top of the deep seal trap shall have a [3] ⁄ 4 of an inch (19.1 mm) opening located at the highest point of the trap to serve as a siphon breaker. Outlets shall be taken off from the side in such a manner as to allow

a waterline to be maintained that will permanently occupy not

182 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

INDIRECT WASTES
CPC § 910.0 Medium relevance — show source text
910.0 Combination Waste and Vent Systems. 910.1 Where Permitted. Combination waste and vent systems shall be permitted where structural conditions preclude the installation of conventional systems as otherwise prescribed by this code. 910.2 Approval. Construction documents for each combination waste and vent system shall first be approved by the Authority Having Jurisdiction before a portion of such system is installed.

910.3 Vents. Each combination waste and vent system, as defined in Chapter 2, shall be provided with a vent or vents adequate to ensure free circulation of air. A branch exceeding 15 feet (4572 mm) in length shall be separately vented in an approved manner. The area of a vent installed in a combination waste and vent system shall be not less than one-half the inside cross-sectional area of the drainpipe served. The vent connection shall be downstream of the uppermost fixture. 910.4 Connections and Size. Branches serving traps shall connect to the main line at an angle not exceeding 2 percent. Each waste pipe and each trap in such a system shall be not less than two pipe sizes exceeding the sizes required by Chapter 7 of this code, and not less than two pipe sizes exceeding a fixture tailpiece or connection. 910.5 Vertical Waste Pipe. No vertical waste pipe shall be used in such a system, except the tailpiece or connection between the outlet of a plumbing fixture and the trap. Such tailpieces or connections shall be as short as possible, and in no case shall exceed 2 feet (610 mm).

Exception: Branch lines shall be permitted to have 45 degree (0.79 rad) vertical offsets.

910.6 Cleanouts. An accessible cleanout shall be installed in each vent for the combination waste and vent system. Cleanouts shall not be required on a wet-vented branch serving a single trap where the fixture tailpiece or connection is not less than 2 inches (50 mm) in diameter and provides ready access for cleaning through the trap.

910.7 Fixtures. No water closet or urinal shall be installed on such a system. Other one, two, or three unit fixtures remotely located from the sanitary system and adjacent to a combination waste and vent system shall be permitted to be connected to such system in the conventional manner by means of waste and vent pipes of regular sizes, providing that the two pipe size increase required in Section 910.4 is based on the total fixture unit load connected to the system.

See Appendix B of this code for explanatory notes on the design of combination waste and vent systems.

911.0 Circuit Venting. 911.1 Circuit Vent Permitted. A maximum of eight flooroutlet water closets, showers, bathtubs, or floor drains con

2025 CALIFORNIA PLUMBING CODE 191

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

VENTS

nected to a horizontal branch shall be permitted to be circuit vented. Each trap arm shall connect horizontally to the horizontal branch being circuit vented in accordance with Table 1002.2. The horizontal branch shall be classified as a drain and a vent from the most downstream trap arm connection to the most upstream trap arm connection to the horizontal branch.

Exception: Back-outlet and wall-hung water closets shall be permitted to be circuit vented provided that no floor-outlet fixtures are connected to the same horizontal branch. Backoutlet and wall-hung water closets shall connect horizontally to the horizontal circuit vented drain.

Frequently asked questions

What if I can’t find §§ 216.0 or 217.0 in my copy of the CPC?

I could not locate § 216.0 or § 217.0 in the uploaded CPC files. Use the Chapter 10 trap and interceptor sections (examples: § 1001.2, § 1005.1, § 1009.1) and Definitions § 222.0 as the governing text for traps and interceptors.

Minimum and maximum trap seal depths — what are they?

Each fixture trap must have a liquid seal of not less than 2 inches and not more than 4 inches, unless the AHJ requires a deeper seal. § 1005.1.

Are floor drains required to have trap primers?

Floor drains or similar traps subject to infrequent use shall be protected with a trap‑seal primer unless the AHJ says it’s unnecessary; primers must be accessible for maintenance. § 1007.1.

Can I vent an interceptor?

Yes, in some configurations venting may be omitted where an interceptor acts as a primary settling tank and discharges through an indirect waste into a second properly trapped and vented interceptor — see § 902.1 (Chapter 9).

How do I size a grease interceptor?

Use Table 1014.3.6 (DFUs → interceptor volume) or size by actual (peak) flow rate × 30 minutes retention and select the next nominal volume. See the code example (12 DFU → 750 gallons). § 1014.3.6.

Ask about the CPC

Get cited, plain-English answers on the California Plumbing Code for your project — any code section, any scenario.

Start Free Trial

Related in the CPC

What is a 'Lavatory' and 'Lavatories in sets'?

What does 'Water closet' (toilet) include under CPC definitions?

Leader, downspout and other roof drainage terms

Fixture & appliance definitions (L–S)

California Plumbing Code

Definitions for traps, interceptors and related devices

What the code requires — plain English (controlling sections)

Requirements in detail

Key defined terms (first mentions are bold)

Concrete numeric limits and controls (summary table)

Traps — material & installation highlights

Trap seal protection & primers

Interceptors (clarifiers) — where to use and how to design

Exceptions & special cases

Common mistakes (inspection / design traps & interceptors)

Worked example — kitchen grease interceptor sizing (from the code example)

Related provisions (quick navigation)

Code references

Frequently asked questions

More in California Plumbing Code

Ask about the CPC

Related in the CPC