CPC · California Plumbing Code

When is storm drainage required and where can it discharge?

Q: Are homeowners allowed to let roof runoff flow onto the street or lawn?

Yes, there is a specific allowance for one- and two-family dwellings to discharge to flat areas (streets or lawns) provided the water flows away from the building and away from adjoining property and does not create a nuisance ( § 1101.2 ) .

Q: Who decides an “approved place of disposal”?

The Authority Having Jurisdiction (the local enforcing/permitting agency) must approve any alternate disposal location when a public storm sewer is not available ( § 1101.2 ) .

Q: Is it ever acceptable to mix storm and sanitary systems inside a building?

Only where a combined sewer is used (i.e., the public system is combined). Otherwise the sanitary and storm drainage systems must be entirely separate as required by Chapter 11 (see § 1101.2 and related sections) .

If your roof, yard, or paved area collects rain, the CPC requires you to drain that water to a public storm sewer when one exists; if not, you must use a combined sewer or another location approved by the local authority. Under no circumstance may storm water be sent into a sanitary-only sewer; one- and two-family homes have a limited allowance to discharge onto flat areas if the flow moves away from buildings and neighbors and doesn’t create a nuisance (see **§ 1101.1**, **§ 1101.2**, **§ 1101.3**)

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Plumbing Code requires that areas that collect rainwater (for example roofs, paved areas, yards, courtyards, vent shafts, and light wells) be drained to a separate storm sewer system where available — or to a combined sewer system or another approved place of disposal if a separate storm sewer is not available (§ 1101.2) . Chapter 11 of the CPC governs storm drainage materials, design and installation (§ 1101.1) . Importantly, storm water shall not be drained into sewers intended for sanitary drainage — that discharge is expressly prohibited (§ 1101.3) .

The single most important rule: drain rainwater to a storm system (or approved alternate) — never into a sanitary-only sewer. See § 1101.2 and § 1101.3.

Requirements in detail

Scope / applicability

The chapter controls the materials, design, and installation of storm water drainage systems (§ 1101.1) .
Areas specifically listed that must be drained include roofs, paved areas, yards, courts, courtyards, vent shafts, light wells, or similar rainwater-collecting areas (§ 1101.2) .

Where storm drainage must go (decision dimensions)

Decision question	Code rule / allowed discharge(s)	Code Reference
Area to be drained (e.g., roof, paved area, yard)	Drain into a separate storm sewer system when available	§ 1101.2
If a separate storm sewer is not available	Drain into a combined sewer system or some other place of disposal approved by the Authority Having Jurisdiction	§ 1101.2
One- and two-family dwellings (special allowance)	May discharge to flat areas (streets or lawns) provided water flows away from the building and adjoining property and does not create a nuisance	§ 1101.2
Prohibition	Storm water shall not be drained into sewers intended for sanitary drainage	§ 1101.3

Notes:

“Authority Having Jurisdiction” is the permitting/enforcement authority that may approve alternative disposal locations when the public storm system is not available; the code repeatedly defers to that authority for approvals (see § 1101.2) .
The chapter’s applicability and enforcement are set out in the general Chapter 11 scope (§ 1101.1) .

Exceptions & special cases

One- and two-family dwellings: the CPC specifically permits discharge to flat areas (for example a lawn or street) as long as the water flows away from the building and adjacent properties and does not create a nuisance — this is an explicit allowance within § 1101.2 .
Where a public storm sewer is not present, the Authority Having Jurisdiction may accept other disposal locations (such as an approved watercourse or combined sewer) — that is an approved alternative only if the Authority Having Jurisdiction accepts it (§ 1101.2) .
The general prohibition stands even when a combined sewer exists: storm water may be connected to a combined sewer only where a separate storm sewer is not available (see § 1101.2), but under no circumstances may storm water be routed into a sewer intended solely for sanitary drainage (§ 1101.3) .

Common mistakes

Assuming roof downspouts or paved-area drains may simply tie into the sanitary sewer because “it’s closer.” The CPC explicitly forbids draining storm water into sewers intended for sanitary drainage (§ 1101.3) .
Believing the one- and two-family exception allows free dumping onto neighbors’ property — the exception requires the flow to go away from the building and away from adjoining property and to not create a nuisance (§ 1101.2) .
Installing storm connections without Authority Having Jurisdiction approval when a separate system is not available — the code requires an approved disposal place in that circumstance (§ 1101.2) .
Confusing “combined sewer” (which carries both sanitary and storm in the same system) with a sanitary-only sewer; the latter must not receive storm water (§ 1101.3) .

Worked example — concrete scenario

Scenario: A commercial building has a 2,400 ft² roof in a neighborhood where there is a public storm sewer available.

Rule application: Because roofs must be drained into a separate storm sewer system where available, the building’s roof drainage must connect to the public storm sewer (not the sanitary sewer) — § 1101.2 requires drainage to a separate storm sewer where available and § 1101.3 prohibits discharge to sanitary sewers .
If no public storm sewer existed at the site: the designer would seek Authority Having Jurisdiction approval to connect to a combined sewer or another approved disposal point (again per § 1101.2) .
If the same roof were on a one-family house: the owner could (subject to local regulations) discharge run-off onto a flat lawn or street so long as the water flows away from the house and adjoining properties and does not create a nuisance — this specific allowance is in § 1101.2 .

(Notes: sizing of leaders, gutters and pipe capacity are covered in other sections/tables of Chapter 11 — this example only demonstrates where the flow must go under § 1101.2 and the prohibition in § 1101.3.)

Related provisions

§ 1101.1 — Applicability; chapter scope (materials, design, installation)
§ 1101.2 — Where required; separate storm sewer, combined sewer, approvals, one- & two‑family dwelling allowance
§ 1101.3 — Storm water drainage to sanitary sewers prohibited
See also (other Chapter 11 sections you will commonly consult): § 1101.6 (subsoil drains & permitted discharge locations), § 1101.11 (paved areas), and § 1101.12 (roof drainage primary/secondary) — these expand allowed discharge methods and sizing requirements (Chapter 11) .

Code references

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

CPC § 1101.7 High relevance — show source text
(1) They do not serve continuously flowing springs or groundwater.

(2) The point of discharge is not less than 10 feet (3048 mm) from a property line.

(3) It is impracticable to discharge such drains to a storm drain, to an approved water course, to the front street curb or gutter, or to an alley. 1101.7 Building Subdrains. Building subdrains located below the public sewer level shall discharge into a sump or receiving tank, the contents of which shall be automatically lifted and discharged into the drainage system as required for building sumps. 1101.8 Areaway Drains. Open subsurface space adjacent to a building, serving as an entrance to the basement or cellar of a building, shall be provided with a drain or drains. The areaway drains shall be not less than 2 inches (50 mm) in diameter for areaways at a maximum of 100 square feet (9.29 m [2] ) in area, and shall be discharged in the manner provided for subsoil drains not serving continuously flowing springs or groundwater (see Section 1101.6.1). Areaways exceeding 100 square feet (9.29 m [2] ) shall not drain into subsoil drains.

The drains for areaways exceeding 100 square feet (9.29 m [2] ) shall be sized in accordance with Table 1103.2.

1101.9 Window Areaway Drains. Window areaways at a maximum of 10 square feet (0.93 m [2] ) in area shall be permitted to discharge to the subsoil drains through a 2 inch (50 mm) diameter pipe. However, window areaways exceeding 10 square feet (0.93 m [2] ) in area shall be handled in the manner provided for entrance areaways (see Section 1101.8). 1101.10 Filling Stations and Motor Vehicle Washing Establishments. Public filling stations and motor vehicle washing establishments shall have the paved area sloped toward sumps or gratings within the property lines. Curbs not less than 6 inches (152 mm) high shall be placed where required to direct water to gratings or sumps.

1101.11 Paved Areas. Where the occupant creates surface water drainage, the sumps, gratings, or floor drains shall be piped to a storm drain or an approved water course. 1101.12 Roof Drainage. Roof drainage shall comply with Section 1101.12.1 and Section 1101.12.2.

1101.12.1 Primary Roof Drainage. Roof areas of a building shall be drained by roof drains or gutters. The location and sizing of drains and gutters shall be coordinated with the structural design and pitch of the roof. Unless otherwise required by the Authority Having Jurisdiction, roof drains, gutters, vertical conductors or leaders, and horizontal storm drains for primary drainage shall be sized based on a storm of 60 minutes duration and 100 year return period. Refer to Table D 101.1 (in Appendix D) for 100 years, 60-minute storms at various locations. 1101.12.2 Secondary Drainage. Secondary (emergency) roof drainage shall be provided by one of the methods specified in Section 1101.12.2.1 or Section 1101.12.2.2.
CPC § 19.1 High relevance — show source text
Such subsoil drains shall be permitted to be positioned inside or outside of the footing, shall be of perforated or open-jointed approved drain tile or pipe, not less than 3 inches (80 mm) in diameter, and shall be laid in gravel, slag, crushed rock, approved [3] ⁄ 4 of an inch (19.1 mm) crushed, recycled glass aggregate, or other approved porous material with not less than 4 inches (102 mm) surrounding the pipe. Filter media shall be provided for exterior subsoil piping. Exception: [HCD 1 & HCD 2] Subsoil drains are mandatory only when required by the Authority Having Jurisdiction due to geological conditions.

TABLE 1101.4.6

MATERIALS FOR SUBSOIL DRAINPIPE AND FITTINGS

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STORM DRAINAGE

1101.6.1 Discharge. Subsoil drains shall be piped to a storm drain, to an approved water course, to the front street curb or gutter, to an alley, or the discharge from the subsoil drains shall be conveyed to the alley by a concrete gutter. Where a continuously flowing spring or groundwater is encountered, subsoil drains shall be piped to a storm drain or an approved water course. 1101.6.2 Sump. Where it is not possible to convey the drainage by gravity, subsoil drains shall discharge to an accessible sump provided with an approved automatic electric pump. The sump shall be not less than 15 inches (381 mm) in diameter, 18 inches (457 mm) in depth, and provided with a fitted cover. The sump pump shall have an adequate capacity to discharge water coming into the sump as it accumulates to the required discharge point, and the capacity of the pump shall be not less than 15 gallons per minute (gpm) (0.95 L/s). The discharge piping from the sump pump shall be not less than 1 [1] ⁄ 2 inches (40 mm) in diameter and have a union or other approved quick-disconnect assembly to make the pump accessible for servicing. 1101.6.3 Splash Blocks. For separate dwellings not serving continuously flowing springs or groundwater, the sump discharge pipe shall be permitted to discharge onto a concrete splash block with a minimum length of 24 inches (610 mm). This pipe shall be within 4 inches (102 mm) of the splash block and positioned to direct the flow parallel to the recessed line of the splash block.

1101.6.4 Backwater Valve. Subsoil drains subject to backflow where discharging into a storm drain shall be provided with a backwater valve in the drain line so located as to be accessible for inspection and maintenance. 1101.6.5 Open Area. Nothing in Section 1101.6 shall prevent drains that serve either subsoil drains or areaways of a detached building from discharging to a properly graded open area, provided that:

(1) They do not serve continuously flowing springs or groundwater.

(2) The point of discharge is not less than 10 feet (3048 mm) from a property line.

CPC § 0.2 Medium relevance — show source text

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TRAPS AND INTERCEPTORS

less than an 18 inch (457 mm) water seal and shall have a minimum capacity as follows:

(a) Where not more than three motor vehicles are serviced, stored, or both, interceptors shall have a minimum capacity of 6 cubic feet (0.2 m [3] ), and 1 cubic foot (0.03 m [3] ) of capacity shall be added for each vehicle up to 10 vehicles.

(b) Above 10 vehicles, the Authority Having Jurisdiction shall determine the size of the interceptor required.

(c) Where vehicles are serviced and not stored, interceptor capacity shall be based on a net capacity of 1 cubic foot (0.03 m [3] ) for each 100 square feet (9.29 m [2] ) of the surface to be drained into the interceptor, with a minimum of 6 cubic feet (0.2 m [3] ).

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CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

CHAPTER 11 - STORM DRAINAGE

(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	SS	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
Adopt Entire Chapter								X			X					X
Adopt Entire Chapter as amended (amended sections listed below)	X			X	X					X		X	X	X	X
Adopt only those sections that are listed below
Chapter/Section
1101.

CPC § 705.10 Medium relevance — show source text

Waste,
and Vent (DWV), Sewer, Sanitary, and Storm Plumbing Sys-
tems for Above and Below Ground Use|Joints|705.10|

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REFERENCED STANDARDS

TABLE 1701.1 (continued) REFERENCED STANDARDS

STANDARD NUMBER	STANDARD TITLE	APPLICATION	REFERENCED SECTION
ASTM C1540-2020	Standard Specification for Heavy-Duty Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings	Joints	705.2.2
ASTM C1563-2008 (R2021)	Standard Test Method for Gaskets for Use in Connection with Hub and Spigot Cast Iron Soil Pipe and Fittings for Sanitary Drain, Waste, Vent, and Storm Piping Applications	Joints	705.2.2
ASTM C1822-2021	Standard Specification for Insulating Covers on Accessible Lavatory Piping	Miscellaneous	403.3
ASTM D1253-2014	Standard Test Method for Residual Chlorine in Water	Miscellaneous	1506.10.6, 1603.4.1
ASTM D1785-2021a	Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120	Piping	Table 604.1, Table 701.2
ASTM D2235-2021	Standard Specification for Solvent Cement for Acrylonitrile- Butadiene-Styrene (ABS) Plastic Pipe and Fittings	Joints	705.1.2
ASTM D2239-2021	Standard Specification for Polyethylene (PE) Plastic Pipe (SIDR-PR) Based on Controlled Inside Diameter	Piping	Table 604.1
ASTM D2241-2020	Standard Specification for Poly (Vinyl Chloride) (PVC) Pressure- Rated Pipe (SDR Series)	Piping	Table 604.1
ASTM D2464-2015	Standard Specification for Threaded Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80	Fittings	Table 604.1
ASTM D2466-2021	Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40	Fittings	Table 604.1
ASTM D2467-2020	Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80	Fittings	Table 604.1
ASTM D2513-2020	Standard Specification for Polyethylene (PE) Gas Pressure Pipe, Tubing, and Fittings	Piping	1208.5.4, 1208.5.6.2, 1208.5.10.2, 1210.1.7.1(1)
ASTM D2564-2020	Standard Specification for Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic Piping Systems	Joints	605.12.2, 705.6.

CPC § 60532-3696. Medium relevance — show source text
SAE Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, PA 15096.

TCNA Tile Council of North America, Inc. 100 Clemson Research Blvd., Anderson, SC 29625.

UL Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, IL 60062.

WQA Water Quality Association, 4151 Naperville Road, Lisle, IL 60532-3696.

WSC Water Systems Council, 1101 30th Street, NW, Suite 500, Washington, D.C. 20007.

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APPENDICES

The appendices are intended to supplement the provisions of the installation requirements of this code. The definitions in Chapter 2 are also applicable to the appendices.

TABLE OF CONTENTS

Page Appendix A Recommended Rules for Sizing the Water Supply System...........................................................................365

Appendix B Explanatory Notes on Combination Waste and Vent Systems ......................................................................381

Appendix C Alternate Plumbing Systems..........................................................................................................................385

Appendix D Sizing Storm Water Drainage Systems..........................................................................................................395

Appendix E Manufactured/Mobile Home Parks and Recreational Vehicle Parks .............................................................405

Appendix F Firefighter Breathing Air Replenishment Systems .........................................................................................417

Appendix G Sizing of Venting Systems ............................................................................................................................423

Appendix H Private Sewage Disposal Systems ................................................................................................................435

Appendix I Installation Standards ....................................................................................................................................447

Appendix J Combination of Indoor and Outdoor Combustion and Ventilation Opening Design.......................................487

Appendix K Potable Rainwater Catchment Systems ........................................................................................................491

Appendix L Sustainable Practices ....................................................................................................................................497

Appendix M Peak Water Demand Calculator ....................................................................................................................517

Appendix N Impact of Water Temperature on the Potential for Scalding and Legionella Growth .....................................525

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TABLE OF CONTENTS (continued)

Appendix O Non-Sewered Sanitation Systems .................................................................................................................531

Appendix P

Professional Qualifications.............................................................................................................................535

Appendix Q

Indoor Horticultural Facilities..........................................................................................................................539

Appendix R Tiny Houses...............................................................................
CPC § 22209-1762. Medium relevance — show source text
CISPI Cast-Iron Soil Pipe Institute, 2401 Fieldcrest Drive, Mundelein, IL 60060.

CSA Canadian Standards Association, 178 Rexdale Boulevard, Toronto, Ontario, Canada, M9W 1R3.

DOE U.S. Department of Energy, Forrestal Building, 1000 Independence Avenue, SW, Washington, DC 20585.

e1 An editorial change since the last revision or reapproval.

ENERGY STAR 1200 Pennsylvania Avenue, N.W., Washington, D.C. 20460.

EPA U.S. Environmental Protection Agency, Office of Wastewater Management (4204M), 1200 Pennsylvania Avenue, N.W., Washington, D.C. 20460.

IAPMO International Association of Plumbing and Mechanical Officials, 4755 E. Philadelphia Street, Ontario, CA 91761.

ICC International Code Council, 500 New Jersey Avenue, NW, 6th Floor, Washington, DC 20001.

ISEA International Safety Equipment Association, 1901 N. Moore Street, Suite 808, Arlington, VA 22209-1762.

ISO International Organization for Standardization, 1 ch. de la Voie-Creuse, Casa Postale 56, CH-1211 Geneva 20, Switzerland.

MSS Manufacturers Standardization Society of the Valve and Fittings Industry, 127 Park Street, NE, Vienna, VA 22180.

NFPA National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471.

NSF NSF International, 789 N. Dixboro Road, Ann Arbor, MI 48105.

PDI Plumbing and Drainage Institute, 800 Turnpike Street, Suite 300, North Andover, MA 01845.

SAE Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, PA 15096.

TCNA Tile Council of North America, Inc. 100 Clemson Research Blvd., Anderson, SC 29625.

UL Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, IL 60062.

WQA Water Quality Association, 4151 Naperville Road, Lisle, IL 60532-3696.

WSC Water Systems Council, 1101 30th Street, NW, Suite 500, Washington, D.C. 20007.

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APPENDICES

The appendices are intended to supplement the provisions of the installation requirements of this code. The definitions in Chapter 2 are also applicable to the appendices.

TABLE OF CONTENTS

Page Appendix A Recommended Rules for Sizing the Water Supply System...........................................................................365

Appendix B Explanatory Notes on Combination Waste and Vent Systems ......................................................................381

Appendix C Alternate Plumbing Systems..........................................................................................................................385

Appendix D Sizing Storm Water Drainage Systems..........................................................................................................395

Appendix E Manufactured/Mobile Home Parks and Recreational Vehicle Parks .............................................................405

Appendix F Firefighter Breathing Air Replenishment Systems .........................................................................................417
CRC § 2025 Medium relevance — show source text
Chapter 24 Fuel Gas.

Chapter 24 is not adopted in California. See California Mechanical Code and California Plumbing Code, Title 24, Parts 4 and 5.

Chapter 25 Plumbing Administration.

Chapter 25 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 26 General Plumbing Requirements.

Chapter 26 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 27 Plumbing Fixtures.

Chapter 27 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 28 Water Heaters.

Chapter 28 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 29 Water Supply and Distribution.

Chapter 29 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 30 Sanitary Drainage.

Chapter 30 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 31 Vents.

Chapter 31 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 32 Traps.

Chapter 32 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 33 Storm Drainage.

Chapter 33 is not adopted in California. See California Plumbing Code, Title 24, Part 5.

Chapter 34 General Requirements.

Chapter 34 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 35 Electrical Definitions.

Chapter 35 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 36 Services.

Chapter 36 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 37 Branch Circuit and Feeder Requirements.

Chapter 37 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 38 Wiring Methods.

Chapter 38 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 39 Power and Lighting Distribution.

Chapter 39 is not adopted in California. See California Electrical Code, Title 24, Part 3.

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Chapter 40 Devices and Luminaires.

Chapter 40 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 41 Appliance Installation.

Chapter 41 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 42 Swimming Pools.

Chapter 42 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 43 Class 2 Remote-control, Signaling and Power-limited Circuits.

Chapter 43 is not adopted in California. See California Electrical Code, Title 24, Part 3.

Chapter 44 Referenced Standards.
CPC § 312.0 Medium relevance — show source text
312.0 Protection of Piping, Materials, and Structures

314.0 Trenching, Excavation, and Backfill

701.3 Drainage Fittings

705.5.1.1 Butt Fusion Joints

705.5.1.2 Electro-Fusion Joints

705.5.1.3 Socket-Fusion Joints

723.0 Building Sewer Test

TABLE 1

CLEANOUTS (See Section 4.6.1)

The following standards from Tables 1701.1 and 1701.2 of the 2024 Uniform Plumbing Code apply.

Table 1701.1 Standards

ASTM D2239 Polyethylene (PE) Plastic Pipe (SIDRPR) Based on Controlled Inside Diameter

ASTM D2683 Socket-Type Polyethylene Fittings for Outside Diameter-Controlled Polyethylene Pipe and Tubing

ASTM D3261 Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene (PE) Plastic Pipe and Tubing

ASTM F714 Polyethylene (PE) Plastic Pipe (DRPR) Based on Outside Diameter

ASTM F894 Polyethylene (PE) Large Diameter Profile Wall Sewer and Drain Pipe

ASTM F1055 Electrofusion Type Polyethylene Fittings for Outside Diameter Controlled Polyethylene and Crosslinked Polyethylene (PEX) Pipe and Tubing

ASTM F2620 Heat Fusion Joining of Polyethylene Pipe and Fittings

Table 1701.2 Standards

ASTM D2657 Heat Fusion Joining of Polyolefin Pipe and Fittings

IAPMO PS 25 Metallic Fittings for Joining Polyethylene Pipe for Water Service and Yard Piping

Note: For SI units: 1 inch = 25 mm

2025 CALIFORNIA PLUMBING CODE 453

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454 2025 CALIFORNIA PLUMBING CODE

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"The information contained in this appendix is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this appendix may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard."

The following IAPMO Installation Standard is included here for the convenience of the users of the Uniform Plumbing Code. It is not considered as a part of the Uniform Plumbing Code unless formally adopted as such. This Installation Standard is an independent, stand-alone document published by the International Association of Plumbing and Mechanical Officials and is printed herein by the expressed written permission of IAPMO.

INSTALLATION STANDARD FOR PEX TUBING SYSTEMS

FOR HOT- AND COLD-WATER DISTRIBUTION

IAPMO IS 31-2022

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

1 Scope

1.1 General

1.1.1 This Standard specifies requirements for the installation of SDR 9 CTS crosslinked polyethylene (PEX) tubing and fittings, including cold-expansion, crimp, press, and mechanical compression fittings, intended for hot- and cold-water distribution systems within buildings.

1.1.2 This Standards applies to
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.

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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 § 309.0 Medium relevance — show source text
2025 CALIFORNIA PLUMBING CODE 469

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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

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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|

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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

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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 § 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.|
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IS 33

FIGURE 1

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

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IS 33

FIGURE 2

THRUST BLOCK BEARING AREA (See Section 5.2.2)

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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 § 1015.0 High relevance — show source text
1015.0 FOG (Fats, Oils, and Greases) Disposal System . . . . . . . . . . . . . .199

1015.1 Purpose . . . . . . . . . . . . . . . . . . . .199

1015.2 Components, Materials, and Equipment . . . . . . . . . . . . . . . . . .200

1015.3 Sizing and Installation . . . . . . . . .200

1015.4 Performance . . . . . . . . . . . . . . . . .200

1016.0 Sand Interceptors . . . . . . . . . . . . .200

1016.1 Discharge . . . . . . . . . . . . . . . . . . .200

1016.2 Authority Having Jurisdiction . . . .200

1016.3 Construction and Size . . . . . . . . .200

1016.4 Separate Use . . . . . . . . . . . . . . . .200

1017.0 Oil and Flammable Liquid Interceptors . . . . . . . . . . . . . . . . . .200

1017.1 Interceptors Required . . . . . . . . . .200

1017.2 Interceptor Design Alternatives . . .200

1017.3 Interceptor Details . . . . . . . . . . . .200

1017.4 Design of Interceptors . . . . . . . . .200

CHAPTER 11 STORM DRAINAGE . . . . . . . . . .203

1101.0 General . . . . . . . . . . . . . . . . . . . . .205

1101.1 Applicability . . . . . . . . . . . . . . . . . .205

1101.2 Where Required . . . . . . . . . . . . . .205

1101.3 Storm Water Drainage to Sanitary Sewer Prohibited . . . . . .205

1101.4 Material Uses . . . . . . . . . . . . . . . .205

Table 1101.4.6 Materials for Subsoil Drainpipe and Fittings . . . . . . . . . . . . . . . . . .205

1101.5 Expansion Joints Required . . . . . .205

1101.6 Subsoil Drains . . . . . . . . . . . . . . .205

1101.7 Building Subdrains . . . . . . . . . . . .206

1101.8 Areaway Drains . . . . . . . . . . . . . .206

1101.9 Window Areaway Drains . . . . . . .206

1101.10 Filling Stations and Motor Vehicle Washing Establishments . . . . . . . . . . . . . . .206

1101.11 Paved Areas . . . . . . . . . . . . . . . . .206

1101.12 Roof Drainage . . . . . . . . . . . . . . .206

1101.13 Cleanouts . . . . . . . . . . . . . . . . . . .207

1101.14 Rainwater Sumps . . . . . . . . . . . . .207
CPC § 1101.1 High relevance — show source text
1101.1 Applicability . . . . . . . . . . . . . . . . . .205

1101.2 Where Required . . . . . . . . . . . . . .205

1101.3 Storm Water Drainage to Sanitary Sewer Prohibited . . . . . .205

1101.4 Material Uses . . . . . . . . . . . . . . . .205

Table 1101.4.6 Materials for Subsoil Drainpipe and Fittings . . . . . . . . . . . . . . . . . .205

1101.5 Expansion Joints Required . . . . . .205

1101.6 Subsoil Drains . . . . . . . . . . . . . . .205

1101.7 Building Subdrains . . . . . . . . . . . .206

1101.8 Areaway Drains . . . . . . . . . . . . . .206

1101.9 Window Areaway Drains . . . . . . .206

1101.10 Filling Stations and Motor Vehicle Washing Establishments . . . . . . . . . . . . . . .206

1101.11 Paved Areas . . . . . . . . . . . . . . . . .206

1101.12 Roof Drainage . . . . . . . . . . . . . . .206

1101.13 Cleanouts . . . . . . . . . . . . . . . . . . .207

1101.14 Rainwater Sumps . . . . . . . . . . . . .207

1101.15 Traps on Storm Drains and Leaders . . . . . . . . . . . . . . . . . . . . .207

1101.16 Leaders, Conductors, and

Connections . . . . . . . . . . . . . . . . .207

1102.0 Roof Drains . . . . . . . . . . . . . . . . . .207

1102.1 Applications . . . . . . . . . . . . . . . . .207

1102.2 Dome Strainers Required . . . . . . .207

1102.3 Roof Drain Flashings . . . . . . . . . .207

1103.0 Size of Leaders, Conductors,

and Storm Drains . . . . . . . . . . . . .207

1103.1 Vertical Conductors and

Leaders . . . . . . . . . . . . . . . . . . . . .207

1103.2 Size of Horizontal Storm

Drains and Sewers . . . . . . . . . . . .207

1103.3 Size of Roof Gutters . . . . . . . . . . .207

1103.4 Side Walls Draining onto a Roof . . . . . . . . . . . . . . . . . .207

Table 1103.1 Sizing Roof Drains, Leaders, and Vertical Rainwater Piping . . .208

1104.0 Values for Continuous Flow . . . . .208

1104.1 General . . . . . . . . . . . . . . . . . . . . .208

1105.0 Controlled-Flow Roof

Drainage . . . . . . . . . . . . . . . . . . . .208
CPC § 1.11.0. High relevance — show source text
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.

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APPENDIX D

SIZING STORM WATER DRAINAGE SYSTEMS

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

D 101.0 General.

D 101.1 Applicability. This appendix provides general guidelines for the sizing of storm water drainage systems based on maximum rates of rainfall for various cities. The rainfall rates in Table D 101.1 shall be permitted to be used for design unless higher values are established locally.

D 102.0 Sizing by Flow Rate. D 102.1 General. Storm drainage systems shall be permitted to be sized by storm water flow rates, using the gallons per minute per square foot [(L/s)/m [2] ] of rainfall listed in Table D 101.1 for the local area. Multiplying the listed gallons per minute per square foot [(L/s)/m [2] ] by the roof area being drained (in square feet) (m [2] ) by each inlet produces the gallons per minute (gpm) (L/s) of required flow for sizing each drain inlet. The flow rates shall be permitted to be added to determine the flows in each of the drainage systems. Required pipe sizes for various flow rates are listed in Table 1103.1 and Table 1103.2.

D 103.0 Sizing by Roof Area. D 103.1 General. Storm drainage systems shall be permitted to be sized using the roof area served by each of the

drainage systems. Maximum allowable roof areas with various rainfall rates are listed in Table 1103.1 and Table 1103.2, along with the required pipe sizes. By using this method, it shall be permitted to interpolate between two listed rainfall rate columns (inches per hour) (mm/h). To determine the allowable roof area for a listed pipe size at a listed slope, divide the allowable square feet (m [2] ) of the roof for a 1 inch per hour (in/h) (25.4 mm/h) rainfall rate by the listed rainfall rate for the local area. For example, the allowable roof area for a 6 inch (150 mm) drain at [1] ⁄ 8 inch per foot (10.4 mm/m) slope with a rainfall rate of 3.2 in/h (81 mm/h) is 21 400/3.2 = 6688 square feet (621.3 m [2] ).

D 104.0 Capacity of Rectangular Scuppers. D 104.1 General. Table D 104.1 lists the discharge capacity of rectangular roof scuppers of various widths with various heads of water. The maximum allowable level of water on the roof shall be obtained from the registered design professional, based on the design of the roof.

TABLE D 101.1

CPC § 1101.4 Medium relevance — show source text

(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	SS	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
Adopt Entire Chapter								X			X					X
Adopt Entire Chapter as amended (amended sections listed below)	X			X	X					X		X	X	X	X
Adopt only those sections that are listed below
Chapter/Section
1101.4	X			X	X					X		X	X	X	X
1101.4.2.1				X
1101.4.2.2										X		X	X	X	X
1101.6_ Exception_				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.

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CHAPTER 11

STORM DRAINAGE

1101.0 General.

1101.1 Applicability. This chapter shall govern the materials, design, and installation of storm water drainage systems. 1101.2 Where Required. Roofs, paved areas, yards, courts, courtyards, vent shafts, light wells, or similar areas having rainwater, shall be drained into a separate storm sewer system, or into a combined sewer system where a separate storm sewer system is not available, or to some other place of disposal satisfactory to the Authority Having Jurisdiction.

CPC § 2025 Medium 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.

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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 § 505.0 Medium relevance — show source text
Oil-burning and other . . . . . . . . . . . . . . . . . . . . . .505.0 Permits required . . . . . . . . . . . . . . . . . . . . . . . . . .502.0

Pressure-relief valves . . . . . . . . . . .504.4, 504.6, 505.2,

608.2 – 608.5

Protection . . . . . . . . . . . . . . . . . . .504.3 – 504.6, 505.2,

507.2, 507.8, 507.10,

507.14.1, 507.24

Relief valve discharge . . . . . . . . . . . . . . . . . . . . . .608.5 Seismic provisions . . . . . . . . . . . . . . . . . . . . . . . . .507.2 Temperature and pressure-relief valves . . . . . . . . . . . . . . .504.6, 505.2 Temperature-limiting devices . . . . . . . . . . . . . . . . .504.5

Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . .509.0, 510.0

Water heating system requirements . . . . . . . . . . . .501.2 WATER SOFTENERS . . . . . . . . . . . . . . . . 611.4, Table 611.4

WATER STATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225.0

WATER TESTS

Building sewers . . . . . . . . . . . . . . . . . . . . . . . . . . .723.0 Drainage and vent systems . . . . . . . . . . . . .105.3, 712.2 Storm drainage . . . . . . . . . . . . . . . . . .1107.2.1, 1107.2.3 Water supply systems . . . . . . . .105.2.1.1, 105.3, 609.4

WATERPROOFING

AND WATERTIGHT

Building sewer . . . . . . . . . . . . . . . . . . . . . . . . . . . .723.1

Cleanouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .707.3

Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105.3

Drain pans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .507.5

Fixtures . . . . . . . . . . . . . . . . .402.2, 408.6, 408.8, 418.2
CPC § 18001.8 Medium relevance — show source text
Branch. A part of the piping system other than a main, riser, or stack.

Branch, Fixture. See Fixture Branch.

Branch, Horizontal. See Horizontal Branch.

Branch Vent. A vent connecting one or more individual vents with a vent stack or stack vent.

Building. A structure built, erected, and framed of component structural parts designed for the housing, shelter, enclosure, or support of persons, animals, or property of any kind. Exceptions: [HCD 1 & HCD 2] “BUILDING” shall not include the following:

1. Any mobilehome as defined in Health and Safety Code Section 18008.

2. Any manufactured home as defined in Health and Safety Code Section 18007.

3. Any commercial modular as defined in Health and Safety Code Section 18001.8 or any special purpose commer- cial modular as defined in Section 18012.5.

4. Any recreational vehicle as defined in Health and Safety Code Section 18010.

5. Any multifamily manufactured home as defined in Health and Safety Code Section 18008.7.

For additional information, see Health and Safety Code Section 18908.

Building Drain. That part of the lowest piping of a drainage system that receives the discharge from soil, waste, and other drainage pipes inside the walls of the building and conveys it to the building sewer beginning 2 feet (610 mm) outside the building wall. Building Drain (Sanitary). A building drain that conveys sewage only. Building Drain (Storm). A building drain that conveys storm water or another drainage, but no sewage. Building Sewer. That part of the horizontal piping of a drainage system that extends from the end of the building drain and that receives the discharge of the building drain and conveys it to a public sewer, private sewer, private sewage disposal system, or another point of disposal. Building Sewer (Combined). A building sewer that conveys both sewage and storm water or other drainage.

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DEFINITIONS

Building Sewer (Sanitary). A building sewer that conveys sewage only. Building Sewer (Storm). A building sewer that conveys storm water or another drainage, but no sewage. Building Subdrain. That portion of a drainage system that does not drain by gravity into the building sewer. Building Supply. The pipe is carrying potable water from the water meter or another source of water supply to a building or other point of use or distribution on the lot.

205.0 – C –

Category 1. Activities, systems, or equipment whose failure is likely to cause major injury or death to patients, staff, or visitors. [NFPA 99:3.3.162.1] Category 2. Activities, systems, or equipment whose failure is likely to cause minor injury to patients, staff, or visitors.

[NFPA 99:3.3.162.2] Category 3. Activities, systems, or equipment whose failure is not likely to cause injury to patients, staff, or visitors, but can cause discomfort. [NFPA 99:3.3.162.3] **Category 3 Vacuum System.
CPC § 1101.4.2.2 Medium relevance — show source text
1101.4.2.2 [OSHPD 1, 2, 3, 4 & 5] ABS and PVC installations are not allowed.

1101.4.3 Leaders. Leaders installed outside shall comply with the applicable standards referenced in Table 701.2 for aboveground drain, waste, and vent pipe; aluminum sheet metal; galvanized steel sheet metal; or copper sheet metal. 1101.4.4 Underground Building Storm Drains. Underground building storm drains shall comply with the applicable standards referenced in Table 701.2 for underground drain, waste, and vent pipe. 1101.4.5 Building Storm Sewers. Building storm sewers shall comply with the applicable standards referenced in Table 701.2 for building sewer pipe. 1101.4.6 Subsoil Drains. Subsoil drains shall be open jointed, perforated, or both and constructed of materials in conformance with Table 1101.4.6.

TABLE 1101.4.6

MATERIALS FOR SUBSOIL DRAINPIPE AND FITTINGS

MATERIAL REFERENCED STANDARD(S)

PE ASTM F667

PVC ASTM D2729

Vitrified Clay (Extra strength) ASTM C4, ASTM C700

1101.5 Expansion Joints Required. Expansion joints or sleeves shall be provided where warranted by temperature variations or physical conditions. 1101.6 Subsoil Drains. Subsoil drains shall be provided around the perimeter of buildings having basements, cellars, crawl spaces, or floors below grade. Such subsoil drains shall be permitted to be positioned inside or outside of the footing, shall be of perforated or open-jointed approved drain tile or pipe, not less than 3 inches (80 mm) in diameter, and shall be laid in gravel, slag, crushed rock, approved [3] ⁄ 4 of an inch (19.1 mm) crushed, recycled glass aggregate, or other approved porous material with not less than 4 inches (102 mm) surrounding the pipe. Filter media shall be provided for exterior subsoil piping. Exception: [HCD 1 & HCD 2] Subsoil drains are mandatory only when required by the Authority Having Jurisdiction due to geological conditions.

TABLE 1101.4.6

MATERIALS FOR SUBSOIL DRAINPIPE AND FITTINGS

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STORM DRAINAGE

1101.6.1 Discharge. Subsoil drains shall be piped to a storm drain, to an approved water course, to the front street curb or gutter, to an alley, or the discharge from the subsoil drains shall be conveyed to the alley by a concrete gutter. Where a continuously flowing spring or groundwater is encountered, subsoil drains shall be piped to a storm drain or an approved water course. 1101.6.2 Sump. Where it is not possible to convey the drainage by gravity, subsoil drains shall discharge to an accessible sump provided with an approved automatic electric pump.
CPC § 205.0 Medium relevance — show source text
** That part of the horizontal piping of a drainage system that extends from the end of the building drain and that receives the discharge of the building drain and conveys it to a public sewer, private sewer, private sewage disposal system, or another point of disposal. Building Sewer (Combined). A building sewer that conveys both sewage and storm water or other drainage.

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DEFINITIONS

Building Sewer (Sanitary). A building sewer that conveys sewage only. Building Sewer (Storm). A building sewer that conveys storm water or another drainage, but no sewage. Building Subdrain. That portion of a drainage system that does not drain by gravity into the building sewer. Building Supply. The pipe is carrying potable water from the water meter or another source of water supply to a building or other point of use or distribution on the lot.

205.0 – C –

Category 1. Activities, systems, or equipment whose failure is likely to cause major injury or death to patients, staff, or visitors. [NFPA 99:3.3.162.1] Category 2. Activities, systems, or equipment whose failure is likely to cause minor injury to patients, staff, or visitors.

[NFPA 99:3.3.162.2] Category 3. Activities, systems, or equipment whose failure is not likely to cause injury to patients, staff, or visitors, but can cause discomfort. [NFPA 99:3.3.162.3] Category 3 Vacuum System. A Category 3 vacuum distribution system that can be either a wet system designed to remove liquids, air-gas, or solids from the treated area; or a dry system designed to trap liquid and solids before the service inlet and to accommodate air-gas only through the service inlet. [NFPA 99:3.3.20] Category 4. Activities, systems, or equipment whose failure would have no impact on patient care. [NFPA 99:3.3.162.4] Certified Backflow Assembly Tester. A person who has shown competence to test and maintain backflow assemblies to the satisfaction of the Authority Having Jurisdiction. Cesspool. A lined excavation in the ground that receives the discharge of a drainage system or part thereof, so designed as to retain the organic matter and solids discharging therein but permitting the liquids to seep through the bottom and sides.

Chemical Waste. See Special Wastes. Chimney. One or more passageways, vertical or nearly so, for conveying flue or vent gases to the outdoors. [NFPA 54:3.3.17] Chimney, Factory-Built. A chimney composed of listed factory-built components assembled in accordance with the manufacturer’s installation instructions to form the completed chimney. [NFPA 54:3.3.17.2] Chimney, Masonry. A field-constructed chimney of solid masonry units, bricks, stones, listed masonry chimney units, or reinforced Portland cement concrete, lined with suitable chimney flue liners. [NFPA 54:3.3.17.3] Chimney, Metal. A field-constructed chimney of metal.
CPC § 1103.1. Medium relevance — show source text
(9) Scupper openings shall be not less than 4 inches (102 mm) high and have a width equal to the circumference of

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STORM DRAINAGE

the roof drain required for the area served, sized in accordance with Table 1103.1.

(10)Flashings shall extend above the top of the scuppers.

(11)At a wall or parapet, 45 degree (0.79 rad) cants shall be installed.

(12)Separate storm and sanitary drainage systems shall be provided within the building.

(13)Calculations for the roof drainage system shall be submitted along with the plans to the Authority Having Jurisdiction for approval.

TABLE 1105.1(1) CONTROLLED-FLOW MAXIMUM ROOF WATER DEPTH

ROOF RISE*
(inches) MAXIMUM WATER DEPTH AT
DRAIN
(inches)

Flat 3

2 4

4 5

6 6

For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
TABLE 1105.1(2) DISTANCE OF SCUPPER BOTTOMS ABOVE ROOF

ROOF RISE*
(inches) ABOVE ROOF LEVEL
AT DRAIN
(inches)

Flat 3

2 4

4 5

6 6

For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
1105.2 Setback Roofs. Drains on setback roofs shall be permitted to be connected to the controlled-flow drainage systems provided:

(1) The setback is designed for storing water, or

(2) The square footage of the setback drainage area is converted as outlined in Section 1105.0 to gpm, and the storm-water pipe sizes in the controlled-flow system are based on the sum of the loads.

(3) The branch from each of the roof drains that are not provided with controlled flow shall be sized in accordance

with Table 1103.1.

1106.0 Engineered Storm Drainage System. 1106.1 General. The design and sizing of a storm drainage system shall be permitted to be determined by accepted engineering practices. The system shall be designed by a regis

TABLE 1105.1(1) CONTROLLED-FLOW MAXIMUM ROOF WATER DEPTH

For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
TABLE 1105.1(2) DISTANCE OF SCUPPER BOTTOMS ABOVE ROOF

For SI units: 1 inch = 25.4 mm
CPC § 4.2.1 High relevance — show source text
4|X|||X|X|||||X||X|X|X|X|||||||||| |1101.4.2.1||||X||||||||||||||||||||| |1101.4.2.2||||||||||X||X|X|X|X|||||||||| |1101.6_ Exception_||||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.

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CHAPTER 11

STORM DRAINAGE

1101.0 General.

1101.1 Applicability. This chapter shall govern the materials, design, and installation of storm water drainage systems. 1101.2 Where Required. Roofs, paved areas, yards, courts, courtyards, vent shafts, light wells, or similar areas having rainwater, shall be drained into a separate storm sewer system, or into a combined sewer system where a separate storm sewer system is not available, or to some other place of disposal satisfactory to the Authority Having Jurisdiction. In the case of one- and two-family dwellings, storm water shall be permitted to be discharged on flat areas, such as streets or lawns, so long as the storm water shall flow away from the building and away from adjoining property, and shall not create a nuisance. 1101.3 Storm Water Drainage to Sanitary Sewer Pro- hibited. Storm water shall not be drained into sewers intended for sanitary drainage. 1101.4 Material Uses. Pipe, tube, and fittings conveying rainwater shall be of such materials and design as to perform their intended function to the satisfaction of the Authority Having Jurisdiction. Conductors within a vent or shaft shall be of cast-iron, galvanized steel, wrought iron, copper, copper alloy, lead, Schedule 40 ABS DWV, Schedule 40 PVC DWV, stainless steel 304 or 316L [stainless steel 304 pipe and fittings shall not be installed underground and shall be kept not less than 6 inches (152 mm) aboveground], or other approved materials, and changes in direction shall be in accordance with the requirements of Section 706.0. ABS and PVC DWV piping installations shall be installed in accordance with applicable standards referenced in Chapter 17 and 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.
CPC § 1101.16 High relevance — show source text
1101.16 Leaders, Conductors, and

Connections . . . . . . . . . . . . . . . . .207

1102.0 Roof Drains . . . . . . . . . . . . . . . . . .207

1102.1 Applications . . . . . . . . . . . . . . . . .207

1102.2 Dome Strainers Required . . . . . . .207

1102.3 Roof Drain Flashings . . . . . . . . . .207

1103.0 Size of Leaders, Conductors,

and Storm Drains . . . . . . . . . . . . .207

1103.1 Vertical Conductors and

Leaders . . . . . . . . . . . . . . . . . . . . .207

1103.2 Size of Horizontal Storm

Drains and Sewers . . . . . . . . . . . .207

1103.3 Size of Roof Gutters . . . . . . . . . . .207

1103.4 Side Walls Draining onto a Roof . . . . . . . . . . . . . . . . . .207

Table 1103.1 Sizing Roof Drains, Leaders, and Vertical Rainwater Piping . . .208

1104.0 Values for Continuous Flow . . . . .208

1104.1 General . . . . . . . . . . . . . . . . . . . . .208

1105.0 Controlled-Flow Roof

Drainage . . . . . . . . . . . . . . . . . . . .208

1105.1 Application . . . . . . . . . . . . . . . . . .208

Table 1105.1(1) Controlled-Flow Maximum Roof Water Depth . . . . . . . . . . . . .209

Table 1105.1(2) Distance of Scupper Bottoms Above Roof . . . . . . . . . . . . . . . . . .209

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TABLE OF CONTENTS

1105.2 Setback Roofs . . . . . . . . . . . . . . .209

1106.0 Engineered Storm Drainage System . . . . . . . . . . . . . . . . . . . . .209

1106.1 General . . . . . . . . . . . . . . . . . . . . .209

1106.2 Siphonic Roof Drainage Systems . . . . . . . . . . . . . . . . . . . .209

1106.3 Siphonic Roof Drains . . . . . . . . . .209

1107.0 Testing . . . . . . . . . . . . . . . . . . . . .209

1107.1 Testing Required . . . . . . . . . . . . .209

1107.2 Methods of Testing Storm Drainage Systems . . . . . . . . . . . .209

Table 1103.2 Sizing of Horizontal Rainwater Piping . . . . . . . . . . . . .210

Table 1103.3 Size of Gutters . . . . . . . . . . . . . . .211
CPC § 1101.12.2.2 High relevance — show source text
1101.12.2.2 Secondary Roof Drain. Secondary roof drains shall be provided. The secondary roof drains shall be located not less than 2 inches (51 mm) above the roof surface. The maximum height of the roof drains shall be a height to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. The secondary roof drains shall connect to a piping system in accordance with Section 1101.12.2.2.1 or Section 1101.12.2.2.2.

1101.12.2.2.1 Separate Piping System. The secondary roof drainage system shall be a

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separate system of piping, independent of the primary roof drainage system. The discharge shall be above grade, in a location observable by the building occupants or maintenance personnel. Secondary roof drain systems shall be sized in accordance with Section 1101.12.1

based on the rainfall rate for which the primary system is sized. 1101.12.2.2.2 Combined System. The secondary roof drains shall connect to the vertical piping of the primary storm drainage conductor downstream of the last horizontal offset located below the roof. The primary storm drainage system shall connect to the building storm water that connects to an underground public storm sewer. The combined secondary and primary roof drain systems shall be sized in accordance with Section 1103.0 based on double the rain fall rate for the local area.

1101.13 Cleanouts. Cleanouts for building storm drains shall comply with the requirements of Section 719.0 of this code.

1101.13.1 Rain Leaders and Conductors. Rain leaders and conductors connected to a building storm sewer shall have a cleanout installed at the base of the

leader or conductor before it connects to the horizontal

drain.

1101.14 Rainwater Sumps. Rainwater sumps serving “public use” occupancy buildings shall be provided with dual pumps arranged to function alternately in the case of overload or mechanical failure. Pumps rated 600 V or less shall comply with UL 778 and shall be installed in accordance with the manufacturer’s installation instructions.

1101.15 Traps on Storm Drains and Leaders. Leaders and storm drains, where connected to a combined sewer, shall be trapped. Floor and area drains connected to a storm drain shall be trapped.

Exception: Traps shall not be required where roof drains, rain leaders, and other inlets are at locations permitted under Section 906.0, Vent Termination.

1101.15.1 Where Not Required. No trap shall be required for leaders or conductors that are connected to a sewer carrying storm water exclusively. 1101.15.2 Trap Size. Traps, where installed for individual conductors, shall be the same size as the horizontal drain to which they are connected.

1101.15.3 Method of Installation of Combined Sewer. Individual storm-water traps shall be installed on the stormwater drain branch serving each storm-water inlet, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer. Such traps shall be provided with an accessible cleanout on the outlet side of the trap.
CPC § 1101.11 High relevance — show source text
1101.11 Paved Areas. Where the occupant creates surface water drainage, the sumps, gratings, or floor drains shall be piped to a storm drain or an approved water course. 1101.12 Roof Drainage. Roof drainage shall comply with Section 1101.12.1 and Section 1101.12.2.

1101.12.1 Primary Roof Drainage. Roof areas of a building shall be drained by roof drains or gutters. The location and sizing of drains and gutters shall be coordinated with the structural design and pitch of the roof. Unless otherwise required by the Authority Having Jurisdiction, roof drains, gutters, vertical conductors or leaders, and horizontal storm drains for primary drainage shall be sized based on a storm of 60 minutes duration and 100 year return period. Refer to Table D 101.1 (in Appendix D) for 100 years, 60-minute storms at various locations. 1101.12.2 Secondary Drainage. Secondary (emergency) roof drainage shall be provided by one of the methods specified in Section 1101.12.2.1 or Section 1101.12.2.2.

1101.12.2.1 Roof Scuppers or Open Side. Secondary roof drainage shall be provided by an opensided roof or scuppers where the roof perimeter construction extends above the roof in such a manner that water will be entrapped. An open-sided roof or scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. Scupper openings shall be not less than 4 inches (102 mm) high and have a width equal to the circumference of the roof drain required for the area served, sized in accordance with Table 1103.1.

1101.12.2.2 Secondary Roof Drain. Secondary roof drains shall be provided. The secondary roof drains shall be located not less than 2 inches (51 mm) above the roof surface. The maximum height of the roof drains shall be a height to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. The secondary roof drains shall connect to a piping system in accordance with Section 1101.12.2.2.1 or Section 1101.12.2.2.2.

1101.12.2.2.1 Separate Piping System. The secondary roof drainage system shall be a

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separate system of piping, independent of the primary roof drainage system. The discharge shall be above grade, in a location observable by the building occupants or maintenance personnel. Secondary roof drain systems shall be sized in accordance with Section 1101.12.1

based on the rainfall rate for which the primary system is sized. 1101.12.2.2.2 Combined System. The secondary roof drains shall connect to the vertical piping of the primary storm drainage conductor downstream of the last horizontal offset located below the roof. The primary storm drainage system shall connect to the building storm water that connects to an underground public storm sewer. The combined secondary and primary roof drain systems shall be sized in accordance with Section 1103.0 based on double the rain fall rate for the local area.
CPC § 1101.3 High relevance — show source text
1101.3 Storm Water Drainage to Sanitary Sewer Pro- hibited. Storm water shall not be drained into sewers intended for sanitary drainage. 1101.4 Material Uses. Pipe, tube, and fittings conveying rainwater shall be of such materials and design as to perform their intended function to the satisfaction of the Authority Having Jurisdiction. Conductors within a vent or shaft shall be of cast-iron, galvanized steel, wrought iron, copper, copper alloy, lead, Schedule 40 ABS DWV, Schedule 40 PVC DWV, stainless steel 304 or 316L [stainless steel 304 pipe and fittings shall not be installed underground and shall be kept not less than 6 inches (152 mm) aboveground], or other approved materials, and changes in direction shall be in accordance with the requirements of Section 706.0. ABS and PVC DWV piping installations shall be installed in accordance with applicable standards referenced in Chapter 17 and 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.

[HCD 1 & HCD 2] ABS or PVC installations are limited to not more than two stories of areas of residential accommo- dation.

[OSHPD 1, 2, 3, 4 & 5] ABS and PVC installations are not allowed.

1101.4.1 Copper and Copper Alloys. Joints and connections in copper and copper alloy pipe and tube shall be installed in accordance with Section 705.3.

1101.4.2 Conductors. Conductors installed aboveground in buildings shall comply with the applicable standards referenced in Table 701.2 for aboveground drain, waste, and vent pipe. Conductors installed aboveground level shall be of seamless copper water tube, Type K, L, or M; Schedule 40 copper pipe or Schedule

40 copper alloy pipe; Type DWV copper drainage tube; service weight cast-iron soil pipe or hubless cast-iron soil pipe; standard weight galvanized steel pipe; stainless steel 304 or 316L [stainless steel 304 pipe and fittings shall not be installed underground and shall be kept not less than 6 inches (152 mm) aboveground], or Schedule 40 ABS or Schedule 40 PVC plastic pipe. 1101.4.2.1 [HCD 1] ABS or PVC installations are limited to not more than two stories of areas of res- idential accommodation.

1101.4.2.2 [OSHPD 1, 2, 3, 4 & 5] ABS and PVC installations are not allowed.

MATERIAL	REFERENCED STANDARD(S)
PE	ASTM F667
PVC	ASTM D2729
Vitrified Clay (Extra strength)	ASTM C4, ASTM C700

ROOF RISE* (inches)	MAXIMUM WATER DEPTH AT DRAIN (inches)
Flat	3
2	4
4	5
6	6

ROOF RISE* (inches)	ABOVE ROOF LEVEL AT DRAIN (inches)
Flat	3
2	4
4	5
6	6

Frequently asked questions

Can I connect a roof downspout directly into the sanitary sewer?

No. The CPC expressly prohibits draining storm water into sewers intended for sanitary drainage — see § 1101.3 . Roof drainage must go to a separate storm sewer, a combined sewer when no separate system exists, or another Authority-approved disposal point (§ 1101.2) .

What if there is no storm drain in the street?

If a separate storm sewer is not available, storm water may be discharged to a combined sewer or to “some other place of disposal satisfactory to the Authority Having Jurisdiction” — but you must get the Authority’s approval (§ 1101.2) .

Are homeowners allowed to let roof runoff flow onto the street or lawn?

Yes, there is a specific allowance for one- and two-family dwellings to discharge to flat areas (streets or lawns) provided the water flows away from the building and away from adjoining property and does not create a nuisance (§ 1101.2) .

Who decides an “approved place of disposal”?

The Authority Having Jurisdiction (the local enforcing/permitting agency) must approve any alternate disposal location when a public storm sewer is not available (§ 1101.2) .

Is it ever acceptable to mix storm and sanitary systems inside a building?

Only where a combined sewer is used (i.e., the public system is combined). Otherwise the sanitary and storm drainage systems must be entirely separate as required by Chapter 11 (see § 1101.2 and related sections) .

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California Plumbing Code