CPC · California Plumbing Code

What are requirements for rainwater sumps, pumps and backflow protection for subsoil drains?

Q: When is a backwater valve required?

A backwater valve is required where subsoil drains are subject to backflow when discharging into a storm drain; the valve must be accessible for inspection and maintenance per § 1101.6.4 .

Q: What counts as a “public use” building for the dual-pump rule?

“Public use” is the code phrase used in § 1101.14 ; when a rainwater sump serves such an occupancy the sump must have dual alternating pumps . Consult building classification with the Authority Having Jurisdiction to confirm whether your building falls into “public use.” § 1101.14 .

Q: Are there electrical or listing requirements for pumps?

Yes — pumps rated 600 V or less must comply with UL 778 and be installed per the manufacturer's instructions as required by § 1101.14 (applies explicitly to rainwater sumps serving public-use occupancies).

The California Plumbing Code requires subsoil drains that use sumps to have a sump at least 15 in. diameter by 18 in. deep, a pump of at least 15 gpm, discharge piping of at least 1½ in. with a quick-disconnect, and a backwater valve where the drain is subject to backflow; rainwater sumps in public-use buildings must have dual alternating pumps and pumps ≤600 V must meet UL 778 (see §§ 1101.6.2, 1101.6.4, 1101.14).

Ask a question free See coverage

Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

In plain English: subsoil drains that collect groundwater or roof runoff and discharge to a storm drain must use a properly sized sump and sump pump (minimum physical dimensions and a minimum pump capacity), and where the subsoil drain is subject to backflow a backwater valve must be installed in an accessible location. For buildings classified as “public use”, rainwater sumps must have dual pumps arranged to alternate for redundancy; pumps rated 600 V or less must comply with UL 778. These requirements are set out in § 1101.6.2, § 1101.6.4, and § 1101.14 of the California Plumbing Code.

The single most important rule: install a sump meeting the minimum dimensions, equip it with a pump at least 15 gpm and a serviceable discharge connection, and provide an accessible backwater valve where the subsoil drain can be subject to backflow. § 1101.6.2, § 1101.6.4.

Requirements in detail

Minimum sump and pump physical requirements (what the CPC prescribes)

Sump minimum size: not less than 15 inches in diameter and 18 inches in depth. § 1101.6.2.
Pump minimum capacity: the sump pump capacity shall be not less than 15 gallons per minute (gpm) (0.95 L/s). § 1101.6.2.
Discharge piping: discharge piping from the sump pump shall be not less than 1-1/2 inches (40 mm) in diameter. § 1101.6.2.
Serviceability: discharge piping shall include a union or other approved quick-disconnect assembly so the pump is accessible for servicing. § 1101.6.2.

Backflow protection for subsoil drains

Backwater valve required: where subsoil drains are subject to backflow while discharging into a storm drain, provide a backwater valve in the drain line. The valve must be located so it is accessible for inspection and maintenance. § 1101.6.4.

Rainwater sumps for “public use” occupancies (redundancy and electrical compliance)

Dual pumps: rainwater sumps serving “public use” buildings must be provided with dual pumps arranged to function alternately (so one handles flow if the other fails or during overload). § 1101.14.
UL compliance for pumps ≤ 600 V: pumps rated 600 V or less shall comply with UL 778 and be installed per the manufacturer’s instructions. § 1101.14.

Decision table — quick reference for minimums and placement

Item	Minimum / Requirement	Typical application	Code Reference
Sump diameter	15 in. (381 mm)	Subsoil drain receiving water	§ 1101.6.2
Sump depth	18 in. (457 mm)	Subsoil drain receiving water	§ 1101.6.2
Pump capacity	15 gpm (0.95 L/s) minimum	Sump pump minimum	§ 1101.6.2
Discharge pipe	1-1/2 in. (40 mm) minimum	Pump discharge piping	§ 1101.6.2
Service connection	Union or approved quick-disconnect	To remove/repair pump	§ 1101.6.2
Backwater protection	Backwater valve, accessible	Subsoil drain subject to backflow	§ 1101.6.4
Public-use redundancy	Dual alternating pumps	Rainwater sumps for public use buildings	§ 1101.14
Pump electrical standard	UL 778 for pumps ≤ 600 V	Electrical compliance for pumps	§ 1101.14

Exceptions & special cases

The code language cited is prescriptive for minimum physical sizes and minimum pump capacity; it does not replace a hydraulic design if actual inflow rates from soils/groundwater or roof area exceed the pump capacity—those projects require engineering judgment beyond the minimums in § 1101.6.2.
Open-area discharge: where permitted, subsoil drains (that do not serve continuously flowing springs or groundwater) may be discharged to a properly graded open area subject to distance and practicability rules (see related provision § 1101.6.5). This is a controlled exception and has its own conditions.
For areaway drains and building subdrains there are separate sizing and discharge rules (see § 1101.8 and § 1101.7) — do not assume the sump/pump minimums are the only applicable constraints.

Common mistakes

Installing a sump smaller than 15 in. × 18 in. or using a pump rated below 15 gpm — both violate § 1101.6.2.
Using discharge piping smaller than 1-1/2 in. or omitting a union/quick-disconnect, which makes pump servicing difficult and is noncompliant. § 1101.6.2.
Failing to install a backwater valve for subsoil drains that can experience backflow, or installing it in an inaccessible location (violates § 1101.6.4).
For public use buildings: providing a single pump (no redundancy) or using pumps that are not UL 778 listed (when ≤ 600 V) — both conflict with § 1101.14.
Assuming the CPC pump minimum replaces an engineered design — if anticipated inflow exceeds the minimum pump capacity, size pumps per project hydraulics and maintain or exceed code minima. The code sets minima, not always optimum operational sizing.

Worked example — concrete scenario applying the rule

Scenario: A small office building (not classified as “public use”) has a basement subsoil drain that will discharge to the public storm drain and there is measurable risk of storm sewer backflow.

Apply the code:

Provide a sump at least 15 in. diameter × 18 in. deep. § 1101.6.2.
Select a sump pump with capacity ≥ 15 gpm. If site conditions predict a possible inflow of 25 gpm during peak events, select a pump (or pumps) that reliably handle ≥ 25 gpm; the code minimum only requires ≥ 15 gpm, but practical operation requires matching expected inflow. § 1101.6.2.
Install discharge piping of at least 1-1/2 in. diameter with a union (or quick-disconnect) so the pump can be removed for service. § 1101.6.2.
Because the subsoil drain is subject to backflow, install a backwater valve in the drain line and place it where it can be inspected and maintained. § 1101.6.4.

If the building were a municipal library (a public use occupancy), provide dual pumps arranged to alternate; ensure each pump ≤ 600 V complies with UL 778 and follow manufacturer installation instructions. § 1101.14.

Related provisions

§ 1101.6.3 — Splash blocks for separate dwellings; details where discharge onto a splash block is permitted.
§ 1101.6.5 — Open-area discharge rules and minimum distance from property lines when permitted.
§ 1101.7 — Building subdrains (below public sewer level) must discharge into a sump/receiving tank and be lifted into the drainage system as required.
§ 1101.8 — Areaway drain sizing and discharge limits.
§ 1101.13 — Cleanouts for building storm drains and requirements for rain leaders and conductors.
§ 603.5.5 — Protection of water supply inlets to tanks, vats, sumps (air gap, vacuum breaker, or backflow preventer) — relevant if the sump has a potable supply connection.

Code references

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

CPC § 0.95 High relevance — show source text
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.

(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.
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

206 2025 CALIFORNIA PLUMBING CODE

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

STORM DRAINAGE

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 § 603.5.2 High relevance — show source text
603.5.2 Ballcock. Water closet and urinal tanks shall be equipped with a ballcock. The ballcock shall be installed with the critical level not less than 1 inch (25.4 mm) above the full opening of the overflow pipe. In cases where the ballcock has no hush tube, the bottom of the water supply inlet shall be installed 1 inch (25.4 mm) above the full opening of the overflow pipe.

603.5.3 Backflow Prevention. Water closet flushometer tanks shall be protected against backflow by an approved backflow prevention assembly, device, or method.

603.5.4 Heat Exchangers. Heat exchangers used for heat transfer, heat recovery, or solar heating shall protect the potable water system from being contaminated by the

heat-transfer medium. Single-wall heat exchangers used in indirect-fired water heaters shall meet the requirements of Section 505.4.1. Double-wall heat exchangers shall separate the potable water from the heat-transfer medium by providing a space between the two walls that are vented to the atmosphere. 603.5.5 Water Supply Inlets. Water supply inlets to tanks, vats, sumps, swimming pools, and other receptors shall be protected by one of the following means:

(1) An approved air gap.

(2) A listed vacuum breaker installed on the discharge side of the last valve with the critical level not less than 6 inches (152 mm) or in accordance with its listing.

(3) A backflow preventer suitable for the degree of hazard, installed in accordance with the requirements for that type of device or assembly as set forth in this chapter. 603.5.6 Protection from Lawn Sprinklers and Irri- gation Systems. Potable water supplies to systems having no pumps or connections for pumping equipment, and no chemical injection or provisions for chemical injection, shall be protected from backflow by one of the following devices:

(1) Atmospheric vacuum breaker (AVB)

(2) Pressure vacuum breaker backflow prevention assembly (PVB)

(3) Spill-resistant pressure vacuum breaker (SVB)

(4) Reduced-pressure principle backflow prevention assembly (RP)

(5) A valve complying with IAPMO PS 72 603.5.6.1 Systems with Pumps. Where sprinkler and irrigation systems have pumps, connections for pumping equipment, or auxiliary air tanks, or are otherwise capable of creating backpressure, the potable water supply shall be protected by the following type of device where the backflow device is located upstream from the source of backpressure:

(1) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.2 Systems with Backflow Devices. Where systems have a backflow device installed downstream from a potable water supply pump or a potable water supply pump connection, the device shall be one of the following:

(1) Atmospheric vacuum breaker (AVB)

(2) Pressure vacuum breaker backflow prevention assembly (PVB)

(3) Spill-resistant pressure vacuum breaker (SVB)

(4) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.3 Systems with Chemical Injectors. Where systems include a chemical injector or provisions for chemical injection, the potable water supply shall be protected by a reduced-pressure principle backflow prevention assembly (RP).

2025 CALIFORNIA PLUMBING CODE 141
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.

2025 CALIFORNIA PLUMBING CODE 361

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

362 2025 CALIFORNIA PLUMBING CODE

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

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

2025 CALIFORNIA PLUMBING CODE 363

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

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.

2025 CALIFORNIA PLUMBING CODE 361

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

362 2025 CALIFORNIA PLUMBING CODE

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

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

CPC § 0.2 Medium relevance — show source text

200 2025 CALIFORNIA PLUMBING CODE

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] ).

2025 CALIFORNIA PLUMBING CODE 201

202 2025 CALIFORNIA PLUMBING CODE

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 § 1.11.0. Medium relevance — show source text

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. A 3 inch (80 mm) floor drain would thus require a 4 inch (100 mm) trap, and a 4 inch (100 mm) floor drain would require a 5 inch (125 mm) trap for the reasons previously stated.

WHERE IN DOUBT, CHECK WITH YOUR LOCAL Authority Having Jurisdiction.

2025 CALIFORNIA PLUMBING CODE 383

384 2025 CALIFORNIA PLUMBING CODE

CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

APPENDIX C - ALTERNATE PLUMBING SYSTEMS

(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
Adopt Entire Chapter as amended (amended sections listed below)
Adopt only those sections that are listed below
Chapter/Section

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 385

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

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

454 2025 CALIFORNIA PLUMBING CODE

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

"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.

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 § 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 § 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|

340 2025 CALIFORNIA PLUMBING CODE

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 § 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

Frequently asked questions

Do all subsoil drains need a sump pump?

Not always. The CPC requires a sump and pump where building subdrains discharge below public sewer level or where a sump is necessary to lift to the drainage system (see § 1101.7 and the sump requirements in § 1101.6.2). Use project-specific drainage analysis to decide if a sump/pump is required.

When is a backwater valve required?

A backwater valve is required where subsoil drains are subject to backflow when discharging into a storm drain; the valve must be accessible for inspection and maintenance per § 1101.6.4.

What counts as a “public use” building for the dual-pump rule?

“Public use” is the code phrase used in § 1101.14; when a rainwater sump serves such an occupancy the sump must have dual alternating pumps. Consult building classification with the Authority Having Jurisdiction to confirm whether your building falls into “public use.” § 1101.14.

Are there electrical or listing requirements for pumps?

Yes — pumps rated 600 V or less must comply with UL 778 and be installed per the manufacturer's instructions as required by § 1101.14 (applies explicitly to rainwater sumps serving public-use occupancies).

Can I discharge the sump pump onto a splash block?

For separate dwellings (not serving continuously flowing springs/groundwater), the code allows discharge onto a concrete splash block under limited conditions — see § 1101.6.3 for the splash-block arrangement.

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 testing is required for new or altered storm drainage systems and acceptable methods?

What standards and code rules apply to siphonic roof drainage systems and drains?

Engineered storm systems, siphonic drains and testing

California Plumbing Code