CPC · California Plumbing Code
What testing is required for new or altered storm drainage systems and acceptable methods?
If you install or alter storm drainage piping, the CPC requires testing after rough installation by the water or air methods in §§ 1107.1–1107.2.1: plastic pipe must be water‑tested, sectional tests must provide at least a 10‑ft head, and all tests must be held for at least 15 minutes before inspection.
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
New or altered storm drainage systems must be tested to reveal leaks and defects. The mandatory testing requirement is set out in § 1107.1 and directs that testing be performed in accordance with the methods in § 1107.2 (water or air) and the detailed water-test procedure in § 1107.2.1.
The single most important rule: test new or altered storm drainage piping after rough installation using the prescribed water or air tests (but do not air-test plastic pipe) and meet the minimum head and duration requirements before inspection.
Requirements in detail
Scope — which systems must be tested
- New building storm drainage systems and parts of existing systems that are altered, extended, or repaired must be tested. See § 1107.1.
When to test
- Testing is required upon completion of the rough piping installation (i.e., before finishes conceal the piping) per § 1107.2. The Authority Having Jurisdiction (AHJ) may require removal of cleanout plugs to verify the test reaches all parts of the system.
Which piping is excluded or has special rules
- Outside leaders and perforated or open‑jointed drain tile are excepted from the standard piping tests. Plastic pipe shall not be tested with air; use water testing for plastic materials. § 1107.2 specifies these points.
Accepted test methods (overview)
One of the listed methods in § 1107.2 must be used:
- Water test — the primary water procedure and its details are in § 1107.2.1.
- Air test — requirements in § 1107.2.2 (but not allowed for plastic pipe).
Key parameters and how to apply them
Use the table below to decide which test and what minimum values are required.
| Decision dimension | Required value / method | Code Reference |
|---|---|---|
| Which systems must be tested | New systems and altered/extended/repaired parts | § 1107.1 |
| Timing of test | Upon completion of rough piping installation | § 1107.2 |
| Methods allowed | Water test or air test (but see material limits) | § 1107.2 |
| Plastic pipe | Must not be tested with air — use water test | § 1107.2 |
| Minimum head for sectional water testing | 10 foot (3048 mm) head for any section under test; successive sections must include the upper 10 foot of the preceding section so every joint (except the uppermost 10 ft of roof drainage) sees at least a 10 ft head | § 1107.2.1 |
| Filling/holding time for water test | Water shall be kept in the system not less than 15 minutes before inspection | § 1107.2.1 |
| Air-test pressure and duration | 5 psi (34 kPa) uniform gauge pressure (or pressure to balance 10 in. mercury (≈34 kPa)) held not less than 15 minutes | § 1107.2.2 |
| AHJ verification | AHJ may require removal of cleanouts to verify pressure reaches parts of system | § 1107.2 |
| Impractical cases | If water/air tests are impractical, follow § 105.3 for alternative action | § 1107.2.3 (reference to § 105.3) |
How to perform the water test (practical steps from the code)
- Either test the entire system or individual sections. If testing the entire system, close all openings tight except the highest opening, then fill to the point of overflow. § 1107.2.1.
- If testing in sections, no section may be tested with less than a 10‑foot head; when testing successive sections, include the upper 10 feet of the previous section so joints are adequately pressured. Keep water in place 15 minutes before inspection; the system must be tight. § 1107.2.1.
How to perform the air test (practical steps from the code)
- Attach an air compressor apparatus to a suitable opening, close other inlets/outlets, and apply air until a uniform gauge pressure of 5 psi (34 kPa) (or pressure to balance 10 in. mercury) is achieved. Hold that pressure not less than 15 minutes without adding more air. § 1107.2.2.
Exceptions & special cases
- Plastic (ABS/PVC DWV) piping: do not use air testing — use a water test. § 1107.2.
- Outside leaders and perforated/open-jointed drain tile need not be tested with the standard water/air tests. § 1107.2.
- Where air/water tests are impractical, the code points you to § 105.3 for exceptions or alternative testing — consult the AHJ. § 1107.2.3 (see § 105.3).
- The AHJ may require removing cleanout plugs or other temporary openings to ensure the test reaches all piping. § 1107.2.
Common mistakes
- Attempting an air test on plastic pipe (ABS/PVC) — prohibited by § 1107.2.
- Testing a section with less than the required 10 ft head (or failing to include the upper 10 ft of the preceding section) — violates § 1107.2.1.
- Filling the system but not waiting the required 15 minutes before inspection — required by § 1107.2.1.
- Not leaving the highest opening open when filling an entire system for the water test (system must be filled to overflow) — see § 1107.2.1.
- Not coordinating with the AHJ when a test is impractical — the code allows alternatives only through § 105.3 per § 1107.2.3.
Worked example — concrete scenario
Scenario: A roof drainage stack extends vertically 30 feet from the roof drain down through the building. The installer plans to test the piping in two sections (upper and lower).
Code requirements to apply:
- Each tested section must be subjected to at least a 10‑foot (3048 mm) head of water; the upper 10‑foot of the next preceding section must be included when testing successive sections so every joint (except the topmost 10 ft) sees 10 ft head. § 1107.2.1.
- Water must remain in the section not less than 15 minutes before inspection. § 1107.2.1.
Application:
- Divide the 30‑ft vertical stack into two sections: Top section = top 15 ft; Bottom section = lower 15 ft.
- Test the top section first: plug lower openings, leave the highest opening (roof drain) open, fill the section to overflow (which provides more than 10 ft head because the section is 15 ft tall). Wait 15 minutes, inspect for leaks. § 1107.2.1.
- For the bottom section test the code requires including the upper 10 ft of the preceding section. That means when testing the bottom 15‑ft section you must fill so that the upper 10 ft of the top section is also under test pressure — effectively providing at least a 10‑ft head across joints between the sections. Hold water 15 minutes and inspect. § 1107.2.1.
If any portion of the piping is plastic, do not use the air test; use the water test process above. § 1107.2.
Related provisions
- § 1107.0 — General heading for Testing.
- § 1107.1 — Testing required (who/what must be tested).
- § 1107.2 — Methods of testing storm drainage systems (water/air, exclusions, AHJ).
- § 1107.2.1 — Detailed water test procedure (minimum head, holding time).
- § 1107.2.2 — Detailed air test procedure (pressure, duration).
- § 1107.2.3 — Exceptions when standard tests are impractical; refers to § 105.3.
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 25.4 High relevance — show source text
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
- 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.
tered design professional and approved in accordance with Section 301.5.
1106.2 Siphonic Roof Drainage Systems. The design of a siphonic roof drainage system shall comply with ASPE/ANSI 45.
1106.3 Siphonic Roof Drains. Siphonic roof drains shall comply with ASME A112.6.9.
1107.0 Testing. 1107.1 Testing Required. New building storm drainage systems and parts of existing systems that have been altered, extended, or repaired shall be tested in accordance with Section 1107.2.1 or Section 1107.2.2 to disclose leaks and
defects.
1107.2 Methods of Testing Storm Drainage Systems. Except for outside leaders and perforated or open-jointed drain tile, the piping of storm drain systems shall be tested upon completion of the rough piping installation by water or air, except that plastic pipe shall not be tested with air, and proved tight. The Authority Having Jurisdiction shall be permitted to require the removal of cleanout plugs to ascertain whether the pressure has reached parts of the system. One of the following test methods shall be used in accordance with Section 1107.2.1 through Section 1107.2.3. 1107.2.1 Water Test. After piping has been installed, the water test shall be applied to the drainage system, either to the entire system or sections. Where the test is applied to the entire system, all openings in the piping shall be tightly closed except for the highest opening, and the system shall be filled with water to the point of overflow.
CPC § 301.5. High relevance — show source text
tered design professional and approved in accordance with Section 301.5.
1106.2 Siphonic Roof Drainage Systems. The design of a siphonic roof drainage system shall comply with ASPE/ANSI 45.
1106.3 Siphonic Roof Drains. Siphonic roof drains shall comply with ASME A112.6.9.
1107.0 Testing. 1107.1 Testing Required. New building storm drainage systems and parts of existing systems that have been altered, extended, or repaired shall be tested in accordance with Section 1107.2.1 or Section 1107.2.2 to disclose leaks and
defects.
1107.2 Methods of Testing Storm Drainage Systems. Except for outside leaders and perforated or open-jointed drain tile, the piping of storm drain systems shall be tested upon completion of the rough piping installation by water or air, except that plastic pipe shall not be tested with air, and proved tight. The Authority Having Jurisdiction shall be permitted to require the removal of cleanout plugs to ascertain whether the pressure has reached parts of the system. One of the following test methods shall be used in accordance with Section 1107.2.1 through Section 1107.2.3. 1107.2.1 Water Test. After piping has been installed, the water test shall be applied to the drainage system, either to the entire system or sections. Where the test is applied to the entire system, all openings in the piping shall be tightly closed except for the highest opening, and the system shall be filled with water to the point of overflow. Where the system is tested in sections, each opening shall be tightly plugged except for the highest opening of the section under test, and each section shall be filled with water, but no section shall be tested with less than a 10 foot (3048 mm) head of water. In testing successive sections, not less than the upper 10 feet (3048 mm) of the next preceding section shall be tested so that no joint of pipe in the building except the uppermost 10 feet (3048 mm) of a roof drainage system, which shall be filled with water to the flood level of the uppermost roof drain, shall have been submitted to a test of less than 10 foot (3048 mm) head of water. The water shall be kept in the system or the portion of the test for not less than 15 minutes before inspection starts; the system shall then be tight. 1107.2.2 Air Test. The air test shall be made by attaching an air compressor testing apparatus to a suitable opening after closing other inlets and outlets to the system, forcing air into the system until there is a uniform gauge pressure of 5 pounds-force per square inch (psi) (34 kPa) or sufficient pressure to balance a column of mercury 10 inches (34 kPa) in height. This pressure shall be held without the introduction of additional air for not
less than 15 minutes.
1107.2.3 Exceptions. Where circumstances exist that make air and water tests described in Section 1107.2.1 and Section 1107.2.2 impractical, see Section 105.3.
2025 CALIFORNIA PLUMBING CODE 209
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
STORM DRAINAGE
|Col1|Col2|TABLE 1103.
CPC § 106.2.1 High relevance — show source text
K 106.2.1 Size. The roof washer shall be sized to direct rainwater containing debris that has accumulated on the collection surface away from the storage tank. ARCSA/ASPE/ANSI 63 contains additional guidance on acceptable methods of sizing roof washers.
K 106.2.2 Debris Screen. The inlet to the roof washer shall be provided with a debris screen or other approved means that protects the roof washer from the intrusion of debris and vermin. Where the debris screen is installed, the debris screen shall be corrosion resistant and shall have openings not larger than [1] ⁄ 2 of an inch (12.7 mm). K 106.2.3 Drain Discharge. Water drained from the roof washer, or pre-filter shall be diverted away from the storage tank and discharged to a disposal area that does not cause property damage or erosion. Roof washer drainage shall not drain over a public way. K 106.2.4 Automatic Drain. Roof washing systems shall be provided with an automatic means of self-draining between rain events.
K 106.3 Roof Gutters. Gutters shall maintain a minimum slope and be sized in accordance with this code. K 106.4 Drains, Conductors, and Leaders. The design and size of rainwater drains, conductors, and leaders shall comply with this code. K 106.5 Size of Potable Water Piping. Potable rainwater system distribution piping shall be sized in accordance with this code for sizing potable water piping.
K 107.0 Cleaning. K 107.1 General. The interior surfaces of tanks and equipment shall be clean before they are put into service.
K 108.0 Supply System Inspection and Test. K 108.1 General. Rainwater catchment systems shall be inspected and tested in accordance with the applicable provisions of this code for testing of potable water and storm drainage systems. Storage tanks shall be filled with water to the overflow opening for 24 hours, and during the inspection, or by other means as approved by the Authority Having Jurisdiction. Seams and joints shall be exposed during the inspection and checked for water tightness.
496 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE
APPENDIX L - SUSTAINABLE PRACTICES
(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.)
CPC § 1105.1 High relevance — show source text
Table 1105.1(2) Distance of Scupper Bottoms Above Roof . . . . . . . . . . . . . . . . . .209
xxxviii 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
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
CHAPTER 12 FUEL GAS PIPING . . . . . . . . . . .213
1201.0 General . . . . . . . . . . . . . . . . . . . . .215
1201.1 Applicability . . . . . . . . . . . . . . . . . .215
1202.0 Coverage of Piping System . . . . .215
1202.1 General . . . . . . . . . . . . . . . . . . . . .215
1202.2 Piping System Requirements . . . .215
1202.3 Applications . . . . . . . . . . . . . . . . .215
1203.0 Inspection . . . . . . . . . . . . . . . . . . .215
1203.1 Inspection Notification . . . . . . . . .215
1203.2 Excavation . . . . . . . . . . . . . . . . . .215
1203.3 Type of Inspections . . . . . . . . . . .215
1203.4 Inspection Waived . . . . . . . . . . . .216
1204.0 Certificate of Inspection . . . . . . . .216
1204.1 Issuance . . . . . . . . . . . . . . . . . . . .216
1204.2 Gas Supplier . . . . . . . . . . . . . . . . .216
1204.3 Unlawful . . . . . . . . . . . . . . . . . . . .216
1205.0 Authority to Render Gas Service . . . . . . . . . . . . . . . . . . . . .216
1205.1 Authorized Personnel . . . . . . . . . .216
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
xxxviii 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
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 § 101.12.2 Medium relevance — show source text
S 101.12.2 Bypass Connection. A bypass shall be provided for the input connection to the stormwater treatment system. The bypass shall be a diverter valve normally open to the stormwater treatment system. The normally closed port of the diverter valve shall be connected directly to the storm drainage system or combined sewer system in accordance with this code.
TABLE S 101.11(1)
RISK LEVELS
- See Section S 101.2 for other uses approved by the Authority Having Jurisdiction.
S 101.12.3 Overflow Connection. Stormwater treatment overflow shall be connected directly to the storm drainage or combined sewer system in accordance with this code. The overflow shall be provided with a backwater valve at the point of connection to the storm drainage or combined sewer system. The backwater valve shall be accessible for inspection and maintenance.
S 101.12.4 Fail-Safe Mechanisms. Stormwater treatment systems shall be equipped with an automatic shutdown device of the treatment process in the event of a malfunction.
S 101.12.5 Flow Meter Totalizer. Buildings with stormwater treatment systems shall include a flow meter totalizer on the treated stormwater distribution system and a flow meter totalizer on the potable make-up water pipeline to the stormwater treatment system. S 101.12.6 Cross-Connection Inspection and Testing. A cross-connection test is required in accordance with Section 1502.0. Before the building is occupied or the system is activated, the installer shall perform the initial cross-connection test in the presence of the Authority Having Jurisdiction. The test shall be ruled successful by the Authority Having Jurisdiction before final approval is granted. S 101.13 Commissioning. Onsite stormwater treatment systems shall be commissioned in accordance with the requirements of Section S 101.13.1 through Section S 101.13.4.
S 101.13.1 Commissioning Requirements. Commissioning for stormwater treatment systems shall be included in the design and construction processes of the project. Commissioning shall be performed by a person who demonstrates competency in commissioning stormwater treatment systems as required by the Authority Having Jurisdiction. S 101.13.2 Commissioning Plan. The construction documents shall include the commissioning plan for the stormwater treatment system. The commissioning plan shall be approved by the Authority Having Jurisdiction prior to commissioning the stormwater treatment system. The commissioning plan shall include the following:
(1) General project information.
(2) Equipment to be tested, including the test methodology.
(3) Processes to be tested.
(4) Criteria or process for testing.
(5) Criteria or process for acceptance.
(6) Commissioning team contact information.
(7) Commissioning process activities, schedules, and responsibilities.
(8) Plans for the completion of functional performance testing, post construction documentation and training, and the commissioning report. S 101.13.3 Performance Testing. Performance tests shall verify that the installation and operation of the
TABLE S 101.11(2)
MONITORING PARAMETERS
550 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
APPENDIX S
CPC § 8-903.2 Medium relevance — show source text
8-903.2 Residential occupancies.
8-903.2.1 Where toilet facilities are provided, alternative sewage disposal methods may be acceptable if approved by the local health department. In hotels, where private facilities are not provided, water closets at the ratio of one for each 15 rooms may be acceptable.
8-903.2.2 Toilet facilities are not required to be on the same floor or in the same building as sleeping rooms. Water-flush toilets may be located in a building immediately adjacent to the sleeping rooms. When alternative sewage disposal methods are utilized, they shall be located a minimum distance from the sleeping rooms or other locations as approved by the local health department.
8-903.2.3 Kitchen sinks shall be provided in all kitchens. The sink and countertop may be of any smooth nonabsorbent finish which can be maintained in a sanitary condition.
8-903.2.4 Hand washing facilities shall be provided for each dwelling unit and each hotel guest room. A basin and pitcher may be acceptable as adequate hand washing facilities.
8-903.2.5 Hot or cold running water is not required for each plumbing fixture, provided a sufficient amount of water is supplied to permit the fixture’s normal operation.
8-903.2.6 Bathtubs and lavatories with filler spouts less than 1 inch (25.4 mm) above the fixture rim may remain in use, provided there is an acceptable overflow below the rim.
8-903.2.7 Original or salvage water closets, urinals and flushometer valves shall be permitted in qualified historical buildings or properties. Historically accurate reproduction, nonlow-consumption water closets, urinals and flushometer valves shall be permitted except where historically accurate fixtures that comply with the regular code are available.
8-903.3 Materials. New nonhistorical materials shall comply with the regular code requirements. The enforcing agency shall accept alternative materials which do not create a safety hazard where their use is necessary to maintain the historical integrity of the building.
8-903.4 Drainage and vent systems. Plumbing fixtures shall be connected to an adequate drainage and vent system. The enforcing agency may require operational tests for drainage and vent systems which do not comply with applicable requirements of the regular code. Vent terminations may be installed in any location which, in the opinion of the enforcing agency, does not create a safety hazard.
8-903.5 Indirect and special wastes. Indirect and special waste systems shall be installed so that no safety hazard is created. Chemical or industrial liquid wastes which may detrimentally affect the sanitary sewer system shall be pretreated to render them safe prior to discharge.
8-903.6 Traps and interceptors. Traps and interceptors shall comply with the regular code requirements except that the enforcing agency shall accept solutions which do not increase the safety hazard. Properly maintained “S” and drum traps may remain in use.
8-903.7 Joints and connections.
8-903.7.1 Joints and connections in new plumbing systems shall comply with applicable requirements of the regular code.
8-903.7.2 Joints and connections in existing or restored systems may be of any type that does not create a safety hazard.
8-903.8 Water distribution. Plumbing fixtures shall be connected to an adequate water distribution system. The enforcing agency may require operational tests for water distribution systems which do not comply with applicable requirements of the regular code. Prohibited (unlawful) connections and cross connections shall not be permitted.
CPC § 1701.1 Medium relevance — show source text
Chapter 16 Nonpotable Rainwater Catchment Systems.
Chapter 16 regulates nonpotable rainwater catchment systems that include irrigation; toilet and urinal flushing with proper treatment; provisions where permits are required; maintenance of alternate water sources; and minimum water quality. This chapter provides guidance on how to optimize rainwater use while ensuring there is a decrease of risk to consumers from poor design, installation, and maintenance. Rainwater harvesting is the process of capturing, channeling, and storing water runoff for later use. Most systems are constructed of three principal components: the catchment area, the collection device, and the conveyance system.
Chapter 17 Referenced Standards.
Chapter 17 provides two comprehensive tables with referenced standards. The standards listed in Table 1701.1 are applied as indicated in the applicable reference section(s). A list of additional approved standards, publications, practices, and guides that are not referenced in specific sections appear in Table 1701.2.
Referenced standards set forth specific details of accepted practices, materials specifications, or test methods in many specialized applications. Standards provide an efficient method of conveying complex information and specifications on the performance requirements for materials, products, systems, application, and installation. The manner and purpose for a standard’s use and, in turn, code compliance, must be definitive in all references to the standard. If the standard is intended to be a requirement for judging code compliance, the code must state its intent for use. The standard should adequately address a defined need and at the same time specify the minimum performance requirements, technical characteristics and methods of testing, and required test results.
The referenced standards tables are organized in a manner that makes it easy to find specific standards in alphabetical order, and by acronym of the publishing agency of the standard. The tables list the title of the standard, the edition, and any addenda. Contact information for each publishing agency is provided at the end of the chapter.
Appendix A Recommended Rules for Sizing the Water Supply System.
Appendix A provides a method of sizing the water supply and distribution system that provides precise calculations to establish the proper pressures and flow to the system’s fixtures. The goal of sizing the system is to deliver an acceptable volume of water to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; provide satisfactory water pressure to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; and to prevent excessive water velocity during maximum flow conditions.
Appendix B Explanatory Notes on Combination Waste and Vent Systems.
Appendix B contains general guidelines for the design and installation of combination waste and vent systems. These systems are designed for waste piping and are purposely oversized to serve as both a waste and vent pipe to avoid excessive pneumatic effects at fixture drains.
Appendix C Alternate Plumbing Systems.
The intent of this appendix is to provide clarification of procedures for the design and approval of engineered plumbing systems, alternate materials, and equipment that are not specifically covered in other parts of the code. Alternative methods are allowed to be used where approved by the authority having jurisdiction. Approval of alternatives is based on a demonstration showing that the method or material used is at least equivalent in strength, deflection, and capacity to that provided by the prescriptive methods and materials.
Appendix D Sizing Storm Water Drainage Systems.
Appendix D provides general guidelines for the sizing of stormwater drainage systems. There are two pieces of information that must always be a given. They are the roof size and the rate of rainfall f
CPC § 2025 Medium relevance — show source text
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
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. All methods used to determine volumes and peak flow use historical data. Drain location must be coordinated with the architectural design of the building. When selecting the type of roof drain to use, the roof construction and its thickness, along with the intended use of the roof, are required. Where the roof perimeter extends above the roof in such a manner that water is entrapped and causes ponding, or if any portion of the roof is designed so water can pond, secondary drainage is required. Where secondary drainage is required, scuppers, or a secondary system of roof drains and pipes, are installed to prevent the accumulation of excessive rainwater.
Chapter 12 Fuel Gas Piping.
Chapter 12 regulates the installation of gas piping in a building, structure or within the property lines of buildings up to 5 psi. Gas piping systems must supply the minimum volume of gas required by each gas appliance to perform their proper operation under working conditions without exceeding the maximum pressure specified by each manufacturer. Because of the hazards associated with fuel gas, it is important to ensure the gas system has been inspected and tested, and that it is safe to turn on the gas supply to the building.
Chapter 13 Health Care Facilities and Medical Gas and Medical Vacuum Systems.
Chapter 13 regulates the installation, inspection, testing, maintenance, performance, and safe practices for medical gas and vacuum systems located in health care facilities. This chapter addresses the installation and maintenance of health care fixtures, devices, and equipment. The purpose of medical gas and medical vacuum systems is to provide safe and sufficient flows at required pressures to the medical gas outlet or vacuum inlet terminals. System design and layout should allow convenient access by the medical staff to outlet and inlet terminals, valves, and equipment during patient care or emergencies, as safety is of primary concern.
Chapter 14 Firestop Protection.
CPC § 4.2.1 Medium 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.
2025 CALIFORNIA PLUMBING CODE 203
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
204 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 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 § 409.4 Medium relevance — show source text
409.4, 410.3, 504.5
TEMPORARY USE OF GAS . . . . . . . . . . . . . . . . . . .1207.0
TERMINATION OF VENTS . . . . . . . . . . . . . .509.6.1, 509.8
509.8.1, 906.0, H 501.11
TESTING AGENCY, DEFINITION . . . . . . . . . . . . . . . . . 222.0
TESTS
Air . . . . . . . . . . . . .105.3, 105.3.1, 609.4, 712.3, 723.1,
1107.2.2, 1107.2.3, 1213.1.6
Alternate materials and methods . . . . . . . . . . . . . .301.3
Building sewer . . . . . .102.4.1, 105.2.1, 105.2.1.2, 723.0 Cross-connection . . . . . . . . . . . . . . . . 1502.3, 1502.3.2,
1505.14.2, 1505.14.2.2
Exceptions . . . . . . . . . . . . . . . . . . . . . . .105.3, 1107.2.3
Final . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .712.1
Fuel gas piping . . . . . . . . . . . . . . . . . . . . . . . . . .1213.0 Gauges . . . . . . . . . . . . . . . . . . . . . . . . .318.0, 1203.3.2 Percolation . . . . . . . . . . . . . . . . . . . . . . .1504.3, H 401.0 Reclaimed (recycled) water . . . . . . . . . . . . . . .1505.16 Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105.3 Responsibility for . . . . . . . . . . . . . . . . . . . . . . . .105.2.5 Shower receptors . . . . . . . . . . . . . . . . . . . . . . . .408.8.5 Storm drainage . . . . . . . . . . . . . . . . . . . . . . . . . .1106.0 Testing agency . . . . . . . . . . . . . .222.0, 301.3.1.1, 505.4, 610.2, 1406.4
Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . .609.4, 712.2,
1107.2.1, 1107.2.3
CPC § 140.3 Medium relevance — show source text
140.3(c)5, 170.2(a)3B, 170.2(b) ASTM D2202 120.4(b)2B, 150.0(m)3, 160.3(b)5C, 160.3(c)2C ASTM D2824 110.8(i)4 ASTM D3468 110.8(i)4 ASTM D3805 110.8(i)4 ASTM D5870 110.8(i)4 ASTM D6694 110.8(i)4 ASTM E96 110.8(g)1, 150.0(f) ASTM E283 110.6(a)1, 140.3(a)9, 140.3(a)9B, 150.0(k)1, 150.0(k)1C, 160.5(a)1, 160.5(a)5 ASTM E408 110.8(j) ASTM E903 140.3(d)2E, 140.3(d)3F ASTM E972 110.6(a)4, 140.3(a)5, 170.2(a)3A ASTM E1175 140.3(d)2F ASTM E1677 140.3(a)9 ASTM E1680 140.3(a)9 ASTM E1980-01 110.8(i)3 ASTM E2178 140.3(a)9 ASTM E2357 140.3(a)9 American Society Of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) 120.1(c)2 , 120.1(g) ASHRAE 52.2 120.1(c)1, 150.0(m)12, Table 150.0-B, Table 150.0-C, 160.2(b)1, 160.2(c)1, Table 160.3-A, Table 160.3-B
ASHRAE 62.2 Sections 7.1 and 7.2 150.2(b)1M, 180.2(b)5B ASHRAE climatic data 140.4(b)3, 150.0(h)2, 160.3(b)2, 170(c)2C ASHRAE Handbook 110.3(a)1, 110.3(c)1, 140.4(b)1, 140.4(b)2, 140.4(b)7, 140.4(b)9, 150.0(h), 160.3(b)1, 170.2(c)2 ASHRAE Standard 52.2 120.1(c)1B, 150.0(m)12, Table 150.0-B, Table 150.0-C, 160.2(b)1, 160.2(c)1B, Table 160.3-A, Table 160.3-B ASHRAE Standard 55 140.4(b)2, 170.2(c)2B ASHRAE Standard 62.2 150.0(o), 160.2(b)2
American Society of Mechanical Engineers (ASME) ASME A17.1/CSA B44 120.6(g) Americans with Disabilities Act (ADA) 140.7(a) , 170.2(e)6A Ampere Rating 110.9(c), 110.9(d), 130.0(c)6B, 160.
Frequently asked questions
Can I use an air test on PVC or ABS storm drain piping?
No. The code explicitly prohibits air testing of plastic pipe; use a water test for plastic materials. § 1107.2
What is the minimum head required when testing a section with water?
Each tested section must be tested with not less than a 10‑foot (3048 mm) head of water; successive sections must include the upper 10 ft of the preceding section. § 1107.2.1
How long must water or air pressure be held before inspection?
Hold the water in place not less than 15 minutes before starting inspection for a water test; for an air test, hold the specified pressure not less than 15 minutes. § 1107.2.1, § 1107.2.2
Are outside leaders and perforated drain tile tested the same way?
No. Outside leaders and perforated or open‑jointed drain tile are excepted from the standard water/air piping tests in § 1107.2.
What if testing is impractical on my job?
When the prescribed water and air tests are impractical, follow the alternative procedures in § 105.3 as allowed by § 1107.2.3, and coordinate with the AHJ.
More in California Plumbing Code
- Administration
- Definitions
- General Regulations
- Plumbing Fixtures and Fixture Fittings
- Water Heaters
- Water Supply and Distribution
- Sanitary Drainage (Drain, Waste, and Vent)
- Indirect Wastes
- Vents
- Traps and Interceptors
- Storm Drainage
- Fuel Gas Piping
- Health Care Facilities — Medical Gas and Medical Vacuum Systems
- Alternate Water Sources and Nonpotable Rainwater Catchment Systems
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