Engineered storm systems, siphonic drains and testing

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 § 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 § 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 § 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

  208 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

  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 § 1603.9.1 Medium relevance — show source text

  1603.9.1 Overflow Outlet Size. The overflow outlet

  shall be sized to accommodate the flow of the rainwater

  entering the tank and not less than the aggregate crosssectional area of inflow pipes.

  1603.10 Opening and Access Protection. Rainwater tank openings shall be protected to prevent the entrance of insects, birds, or rodents into the tank and piping systems .

  Rainwater tank access openings exceeding 12 inches (305 mm) in diameter shall be secured to prevent tampering and unintended entry by either a lockable device or other approved method.

  (A) Animals and Insects. Screens installed on vent pipes, inlets, and overflow pipes shall have an aperture of not greater than [1] ∕ 16 of an inch (1.6 mm) and shall be close fit- ting.

  (B) Human Access. A minimum of one access opening shall be provided to allow inspection and cleaning. Rainwater tank manholes and access openings shall be secured by either a lockable device or other approved method to pre- vent unauthorized access.

  1603.11 Marking. Rainwater tanks shall be permanently marked with the capacity and the language: “NONPOTABLE RAINWATER.” Where openings are provided to allow a person to enter the tank, the opening shall be marked with the following language: “DANGER-CONFINED SPACE.”

  1603.12 Storage Tank Venting. Where venting using drainage or overflow piping is not provided or is considered insufficient, a vent shall be installed on each tank. The vent shall extend from the top of the tank and terminate not less than 6 inches (152 mm) above grade and shall be provided with a vent sized in accordance with this code, and based on the size of the influent pipe . The vent terminal shall be directed downward and covered with a [1] ∕ 16 of an inch ( 1.6 mm) mesh screen to prevent the entry of vermin and insects. Tank vent pipes shall not be connected to the sanitary drainage system vent.

  1603.13 Pumps. Pumps serving rainwater catchment systems shall be listed. Pumps supplying water to water closets, urinals, and trap primers shall be capable of delivering not

  «

  «

  «

  «

  «

  «

  330 2025 CALIFORNIA PLUMBING CODE

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

  NONPOTABLE RAINWATER CATCHMENT SYSTEMS

  CAUTION NONPOTABLE RAINWATER, DO NOT DRINK. DO NOT CONNECT TO DRINKING WATER

  SYSTEM. NOTICE: CONTACT BUILDING MANAGE MENT BEFORE PERFORMING ANY WORK ON THIS

  WATER SYSTEM.

  This sign shall be posted in a location that is visible to anyone working on or near rainwater equipment.

  1605.0 Inspection and Testing. 1605.1 General. Rainwater catchment systems shall be inspected and tested in accordance with Section 1605.2 and Section 1605.3.

  1605.2 Supply System Inspection and Test. 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.

• CPC § 5004.2.2.2 Medium relevance — show source text

  3. Sumps and collection systems.
  4. Drainage systems leading to an approved location.
  5. Other approved engineered systems.

  5004.2.2.2 Incompatible materials. Incompatible materials used in open systems shall be separated from each other in the secondary containment system.

  5004.2.2.3 Indoor design. Secondary containment for indoor storage areas shall be designed to contain a spill from the largest vessel plus the design flow volume of fire protection water calculated to discharge from the fire-extinguishing system over the minimum required system design area or area of the room or area in which the storage is located, whichever is smaller. The containment capacity shall be designed to contain the flow for a period of 20 minutes.

  5004.2.2.4 Outdoor design. Secondary containment for outdoor storage areas shall be designed to contain a spill from the largest individual vessel. If the area is open to rainfall, secondary containment shall be designed to include the volume of a 24hour rainfall as determined by a 25-year storm and provisions shall be made to drain accumulations of groundwater and rainwater.

  5004.2.2.5 Monitoring. An approved monitoring method shall be provided to detect hazardous materials in the secondary containment system. The monitoring method is allowed to be visual inspection of the primary or secondary containment, or other approved means. Where secondary containment is subject to the intrusion of water, a monitoring method for detecting water shall be provided. Where monitoring devices are provided, they shall be connected to approved visual or audible alarms.

  5004.2.2.6 Drainage system design. Drainage systems shall be in accordance with the California Plumbing Code and all of the following:

  1. The slope of floors to drains in indoor locations, or similar areas in outdoor locations shall be not less than 1 percent.
  2. Drains from indoor storage areas shall be sized to carry the volume of the fire protection water as determined by the design density discharged from the automatic fire-extinguishing system over the minimum required system design area or area of the room or area in which the storage is located, whichever is smaller.
  3. Drains from outdoor storage areas shall be sized to carry the volume of the fire flow and the volume of a 24-hour rainfall as determined by a 25-year storm.
  4. Materials of construction for drainage systems shall be compatible with the materials stored.
  5. Incompatible materials used in open systems shall be separated from each other in the drainage system.
  6. Drains shall terminate in an approved location away from buildings, valves, means of egress, fire access roadways, adjoining property and storm drains.

  5004.2.3 Containment pallets. Where used as an alternative to spill control and secondary containment for outdoor storage in accordance with the exception in Section 5004.2, containment pallets shall comply with all of the following:

  1. A liquid-tight sump with access for visual inspection shall be provided.
  2. The sump shall be designed to contain not less than 66 gallons (250 L).

  2025 CALIFORNIA FIRE CODE 50-23

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

  HAZARDOUS MATERIALS—GENERAL PROVISIONS

  3. Exposed surfaces shall be compatible with material stored.
  4. Containment pallets shall be protected to prevent collection of rainwater within the sump.

  5004.3 Ventilation. Indoor storage areas and storage buildings shall be provided with mechanical exhaust ventilation or natural ventilation where natural ventilation can be shown to be acceptable for the materials as stored.

• 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 § 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.

  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.

• CPC § 1101.12.2.2 Medium 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 § 301.5.1 Medium relevance — show source text

  301.5.1 Permit Application. The registered design professional shall indicate on the design documents that the plumbing system, or parts thereof, is an alternative engineered design so that it is noted on the construction permit application. The permit and permanent permit records shall indicate that an alternative engineered design was part of the approved installation. 301.5.2 Technical Data. The registered design professional shall submit sufficient technical data to substantiate the proposed alternative engineered design and to prove that the performance meets the intent of this code. 301.5.3 Design Documents. The registered design professional shall provide two complete sets of signed and sealed design documents for the alternative engineered design for submittal to the Authority Having Jurisdiction. The design documents shall include floor plans and a riser diagram of the work. Where appropriate, the design documents shall indicate the direction of flow, pipe sizes, grade of horizontal piping, loading, and location of fixtures and appliances. 301.5.4 Design Approval. An approval of an alternative engineered design shall be at the discretion of the Authority Having Jurisdiction. The exercise of this discretionary approval by the Authority Having Jurisdiction shall have no effect beyond the jurisdictional boundaries of said Authority Having Jurisdiction. An alternative engineered design so approved shall not be considered as in accordance with the requirements, intent, or both of this code for a purpose other than that granted by the Authority Having Jurisdiction. 301.5.5 Design Review. The Authority Having Jurisdiction shall have the authority to require testing of the alternative engineered design in accordance with Section 301.3.1, including the authority to require an independ

  ent review of the design documents by a registered design professional selected by the Authority Having Jurisdiction and at the expense of the applicant. 301.5.6 Inspection and Testing. The alternative engineered design shall be tested and inspected in accordance with the submitted testing and inspection plan and the requirements of this code. 301.6 Tall Wood (Mass Timber) Buildings. Plumbing systems installed in tall wood (mass timber) buildings, shall comply with the following:

  (1) Be designed by a licensed plumbing contractor or a registered design professional in accordance with this code and the building code.

  (2) Be designed to accommodate expansion, contraction, and differential movement between parts of a tall wood (mass timber) building in accordance with Section 312.2. 301.7 One- and Two-Family Dwellings. [HCD 1] The provisions contained in this code shall not apply to one- and two-family dwelling private sewage disposal systems and minimum plumbing facilities when alternate facilities or installations have been approved by the local health author- ity, provided that such alternative facilities or installations provide substantially equivalent or greater protection to health and safety. 301.8 OSHPD 1R. [OSHPD 1R] For OSHPD 1R, refer to Section 309 of the California Existing Building Code for gen- eral requirements.

  302.0 Iron Pipe Size (IPS) Pipe. 302.1 General. Iron, steel, copper, and copper alloy pipe shall be standard-weight iron pipe size (IPS) pipe.

  303.0 Disposal of Liquid Waste. 303.1 General. It shall be unlawful for a person to cause, suffer, or permit the disposal of sewage, human excrement, or other liquid wastes, in a place or manner, except through and by means of an approved drainage system, installed and maintained in accordance with the provisions of this code.

• 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.