CPC · California Plumbing Code

Where may indirect waste receptors be installed and when is AHJ approval required?

Indirect waste receptors (including standpipes) must be sized and located to prevent splashing, be accessible for cleaning, avoid prohibited spaces (except a clothes washer standpipe when washer is in same room), and — importantly — any fixture served by indirect waste must be approved by the local Authority Having Jurisdiction before installation, per **§ 804.1** and **§ 802.1**.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

Indirect waste receptors (including standpipe receptors) must be approved for the use proposed, sized and located to prevent splashing or flooding, and be readily accessible for inspection and cleaning, and some receptor locations are expressly prohibited. The installation of any plumbing fixture served by or receiving indirect waste discharge requires prior approval by the Authority Having Jurisdiction (AHJ). These requirements are set out in § 804.1 and § 802.1 of the California Plumbing Code.

The single most important rule: Every indirect waste receptor must be approved, sized and located to prevent splashing/flooding — and no fixture served by indirect waste shall be installed until the AHJ approves it.

Requirements in detail

Approved receptor — what “approved” means and who decides

  • The receptor must be approved for the use proposed and of a shape and capacity that prevents splashing or flooding and permits cleaning and inspection. This approval and determination of suitability is the responsibility of the AHJ. § 804.1.
  • Separately, the AHJ must approve any plumbing fixture that is served by or receives discharge from an indirect waste pipe before installation. § 802.1.

Location restrictions and accessibility

  • Prohibited locations: No indirect waste receptor shall be installed in a toilet room, closet, cupboard, storeroom, or in a portion of a building not in general use by the occupants. § 804.1.
  • Exception: Standpipes for clothes washers are permitted in toilet and bathroom areas only when the clothes washer is installed in the same room. § 804.1.
  • Receptors must be readily accessible for inspection and cleaning (so consider access panels, clearances, and removable strainers). § 804.1.

Receptor and piping dimensions, traps and lengths (decision‑relevant thresholds)

Use the table below for the common numeric thresholds you’ll apply when deciding receptor type and installation:

Decision dimension Required/Allowed value (bolded) Code reference
Standpipe height for clothes washer above the trap weir Not less than 18 in and not more than 30 in § 804.1
Clothes washer trap rough‑in above floor Not less than 6 in and not more than 18 in; no trap below floor § 804.1
Minimum indirect waste pipe diameter (general) Not less than 1 inch (or not less than the unit drain; minimums vary by equipment) § 801.3.1
Minimum indirect waste pipe diameter (ice‑making machines) Not less than 3/4 in § 801.3.1
Maximum developed indirect waste pipe length (typical) 15 ft (some short runs limited to 5 ft) § 803.3 and § 801.4
Indirect wastes that must discharge through an air gap/air break All indirect waste piping (air gap min. 1 in vertical where required) § 801.2
Receptor accessibility / cleaning Readily accessible for inspection and cleaning § 804.1

(Notes: pipe sizing and some exceptions are detailed elsewhere in Chapter 8; always confirm sizing against the specific equipment and the AHJ.)

AHJ approval — when it is required

  • Before installation: “No plumbing fixtures served by indirect waste pipes or receiving discharge therefrom shall be installed until first approved by the Authority Having Jurisdiction.” § 802.1. This is a pre‑installation approval requirement — not simply post‑inspection acceptance.
  • Approvals typically cover: receptor type and material suitability, receptor location relative to prohibited spaces, trap and standpipe heights, air gap/air break compliance, and routing/sizing of indirect waste piping. (The CPC repeatedly references AHJ approval for materials, design and special installations — see § 803.1 and related sections.)

Exceptions & special cases

  • Clothes washer standpipes are the explicit exception to the general location prohibition: they may be installed in a toilet or bathroom area when the clothes washer is in the same room. § 804.1.
  • Some specialized equipment (sterilizers, certain appliances) must discharge through an air gap or have separate receptor rules; those devices have separate treatment in Chapter 8 (e.g., § 801.6, § 806.1).
  • Where AHJ finds a particular sump pump, pressure‑wasting device, or system is acceptable, limited direct connections or alternate arrangements may be allowed (see § 805.1 for pressure drainage connections and the AHJ’s discretion).

Common mistakes

  • Installing a receptor in a toilet room, closet, cupboard or storeroom without confirming whether the clothes washer exception applies. § 804.1.
  • Failing to obtain AHJ approval before installation of fixtures served by indirect waste pipes (confusing “inspection after install” with the explicit pre‑install approval requirement). § 802.1.
  • Incorrect standpipe heights for clothes washers (below 18 in or above 30 in) or traps installed below the floor (traps must be roughed in 6–18 in above the floor). § 804.1.
  • Using the wrong pipe diameter or exceeding maximum developed length without providing required traps/vents or cleanouts (see § 801.3.1, § 803.3).
  • Not providing an air gap or air break where the code requires one (minimum vertical air‑gap 1 in where a full air gap is required). § 801.2.

Worked example — concrete scenario

Scenario: You are installing a clothes washer standpipe and receptor in a small apartment bathroom where the washer will be located in the same bathroom.

Step‑by‑step CPC application:

  1. Confirm the location exception: Because the clothes washer is installed in the same room, the standpipe may be installed in the bathroom (exception in § 804.1).
  2. Set standpipe height: Specify standpipe top at 24 in above the trap weir — this sits between the code limits 18–30 in required by § 804.1.
  3. Trap rough‑in: Rough‑in the trap so the trap weir is 12 in above the floor (between 6–18 in; trap must not be below the floor). § 804.1.
  4. Pipe diameter and length: Use an indirect waste pipe of at least the unit drain size (commonly 2 in for domestic washers per DFU table) and confirm the developed length does not exceed limits that would require direct trapping or venting per § 803.3 and Table 702.1 for DFU values.
  5. Air gap/air break: Confirm whether an air gap/air break is required for the specific washer discharge and provide it if the appliance or AHJ requires it (see § 801.2).
  6. Obtain AHJ approval before installing the fixture/receptor — submit plans/specs showing standpipe height, trap rough‑in, receptor type and location for approval per § 802.1.

Result: If the AHJ approves the proposed receptor, you may proceed; documentation of that approval should be kept with the project records.

Related provisions (useful cross‑references)

  • § 801.2 — Air gap or air break required for indirect waste piping.
  • § 801.3.1 — Minimum sizes and developed lengths for indirect waste pipes (equipment‑specific).
  • § 803.1 — Materials for indirect waste piping subject to AHJ satisfaction.
  • § 803.3 — Pipe size, length and trapping requirements for indirect waste piping.
  • § 805.1 — Pressure drainage (when direct connections are not permitted unless AHJ approves).
  • § 806.1 — Sterile equipment (air gap requirements for sterilizers).
  • Chapter 8 (Indirect Wastes) overview and definitions — see the beginning of Chapter 8 for scope and purpose.

Code references

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

  • CPC § 803.0 High relevance — show source text

    803.0 Indirect Waste Piping.

    803.1 Materials. Pipe, tube, and fittings conveying indirect waste shall be of such materials and design as to perform their intended function to the satisfaction of the Authority Having Jurisdiction.

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

    803.3 Pipe Size and Length. Except as hereinafter provided, the size of indirect waste piping shall be in accordance with other sections of this code applicable to drainage and vent piping. No vent from indirect waste piping shall combine with a sewer-connected vent. Vents from indirect waste piping shall extend separately to the outside air. Indirect waste pipes exceeding 5 feet (1524 mm), but less than 15 feet (4572 mm) in length shall be directly trapped, but such traps need not be vented.

    Indirect waste pipes less than 15 feet (4572 mm) in length shall be not less than the diameter of the drain outlet or

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    INDIRECT WASTES

    tailpiece of the fixture, appliance, or equipment served, and in no case less than [1] ⁄ 2 of an inch (15 mm). Angles and changes of direction in such indirect waste pipes shall be provided with cleanouts to permit flushing and cleaning.

    804.0 Indirect Waste Receptors.

    804.1 Standpipe Receptors. Plumbing fixtures or other receptors receiving the discharge of indirect waste pipes shall be approved for the use proposed and shall be of such shape and capacity as to prevent splashing or flooding and shall be located where they are readily accessible for inspection and cleaning. No standpipe receptor for a clothes washer shall extend more than 30 inches (762 mm), or not less than 18 inches (457 mm) above its trap weir. No trap for a clothes washer standpipe receptor shall be installed below the floor, but shall be roughed in not less than 6 inches (152 mm) and not more than 18 inches (457 mm) above the floor. No indirect waste receptor shall be installed in a toilet room, closet, cupboard, or storeroom, or in a portion of a building not in general use by the occupants thereof; except standpipes for clothes washers shall be permitted to be installed in toilet and bathroom areas where the clothes washer is installed in the

    same room.

    805.0 Pressure Drainage Connections. 805.1 General. Indirect waste connections shall be provided for drains, overflows, or relief vents from the water supply system, and no piping or equipment carrying wastes or producing wastes or other discharges under pressure shall be directly connected to a part of the drainage system.

    The preceding shall not apply to an approved sump pump or to an approved pressure-wasting plumbing fixture or device where the Authority Having Jurisdiction has been satisfied that the drainage system is adequately sized to accommodate the anticipated discharge thereof.

    806.0 Sterile Equipment.

    806.1 General. Appliances, devices, or apparatus such as stills, sterilizers, and similar equipment requiring water and waste and used for sterile materials shall be drained through an air gap.

    807.0 Appliances.

  • CPC § 801.4 High relevance — show source text

    The piping from the equipment to the receptor shall be not less than the drain on the unit and in no case less than [1] ⁄ 2 of an inch (15 mm).

    801.4 Bar and Fountain Sink Traps. Where the sink in a bar, soda fountain, or counter is so located that the trap serving the sink cannot be vented, the sink drain shall discharge through an air gap or air break (see Section 801.3.3) into an approved receptor that is vented. The developed length from the fixture outlet to the receptor shall not exceed 5 feet (1524 mm). 801.5 Connections from Water Distribution System. Indirect waste connections shall be provided for drains, overflows, or relief pipes from potable water pressure tanks, water heaters, boilers, and similar equipment that is connected to the potable water distribution system. Such indirect waste connections shall be made using a water-distribution air gap constructed in accordance with Table 603.3.1.

    801.6 Sterilizers. Lines, devices, or apparatus such as stills, sterilizers, and similar equipment requiring waste connections and used for sterile materials shall be indirectly connected using an air gap. Each such indirect waste pipe shall be separately piped to the receptor and shall not exceed 15 feet (4572 mm). Such receptors shall be located in the same room. 801.7 Drip or Drainage Outlets. Appliances, devices, or apparatus not regularly classified as plumbing fixtures, but which have a drip or drainage outlets, shall be permitted to be drained by indirect waste pipes discharging into an open receptor through either an air gap or air break (see Section 801.3.1).

    802.0 Approvals. 802.1 General. No plumbing fixtures served by indirect waste pipes or receiving discharge therefrom shall be installed until first approved by the Authority Having Jurisdiction.

    803.0 Indirect Waste Piping.

    803.1 Materials. Pipe, tube, and fittings conveying indirect waste shall be of such materials and design as to perform their intended function to the satisfaction of the Authority Having Jurisdiction.

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

    803.3 Pipe Size and Length. Except as hereinafter provided, the size of indirect waste piping shall be in accordance with other sections of this code applicable to drainage and vent piping. No vent from indirect waste piping shall combine with a sewer-connected vent. Vents from indirect waste piping shall extend separately to the outside air. Indirect waste pipes exceeding 5 feet (1524 mm), but less than 15 feet (4572 mm) in length shall be directly trapped, but such traps need not be vented.

    Indirect waste pipes less than 15 feet (4572 mm) in length shall be not less than the diameter of the drain outlet or

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    tailpiece of the fixture, appliance, or equipment served, and in no case less than [1] ⁄ 2 of an inch (15 mm). Angles and changes of direction in such indirect waste pipes shall be provided with cleanouts to permit flushing and cleaning.

    804.0 Indirect Waste Receptors.

    **804.1 Standpipe Receptors.

  • CPC § 901.0 High relevance — show source text

    APPENDIX Q

    Q 901.0 Sanitary Drainage and Indirect Wastes. Q 901.1 General. Sanitary drainage shall be in accordance with Chapter 7. Indirect wastes shall be in accordance with Chapter 8. The drainage system shall be compatible with the discharge liquid waste.

    Q 901.2 Hazardous Materials. Hazardous materials shall not be discharged into the sanitary sewer, storm drain, or on the ground. Q 901.3 Agricultural Water Waste. Agricultural water shall be discharged in accordance with the local, state, and federal regulations as approved by the Authority Having Jurisdiction. Where agricultural water discharges to the outdoors, and is not connected to the sanitary sewer, the piping shall be installed as to restrict rodents or vermin from entering the building. Q 901.4 Floor Drains, Floor Sinks, and Receptors. Wastewater shall discharge into an approved receptor. Receptors shall be compatible with the wastewater and installed in accordance with this code.

    Q 901.4.1 Plant Storage Areas. Where drains are provided in spaces where plants are stored, such drains shall be installed with indirect waste piping. Each indirect waste pipe from plant storage areas shall be separately piped to the indirect waste receptor and shall not combine with other indirect waste pipes.

    Q 1001.0 Facilities.

    Q 1001.1 Toilet Facilities. Toilet facilities shall be provided in accordance with the occupancy type.

    Q 1001.2 Location. Toilet facilities shall be located in such a manner to prevent contamination of plants during harvesting, holding, manufacturing/processing, and packing.

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    CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

    APPENDIX R - TINY HOUSES

    (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 § 814.3.1 High relevance — show source text

    Condensate drain sizing for other slopes or other conditions shall be approved by the Authority Having Jurisdiction.

    Air-conditioning waste pipes, 1¼ of an inch (32 mm) and larger in size, shall be constructed of materials specified in Chapter 7. Condensate waste piping less than 1¼ of an inch (32 mm) in size shall be permitted to be PVC, CPVC, PE, PP, copper, or other rigid materials approved by the Authority Having Jurisdiction.

    814.3.1 Cleanouts. Condensate drain lines shall be configured or provided with a cleanout to permit the clearing of blockages and for maintenance without requiring the drain line to be cut. 814.4 Appliance Condensate Drains. Condensate drain lines from individual condensing appliances shall be sized as required by the manufacturer’s instructions. Condensate drain lines serving more than one appliance connecting to a common indirect waste pipe shall have the connections to the indirect waste pipe protected by a sanitary waste valve complying with ASME A112.18.8, condensate trap complying with IAPMO IGC 196, or trap with a trap primer. 814.5 Point of Discharge. Air-conditioning condensate waste pipes shall connect indirectly to the drainage system through an air gap or air break to trapped and vented receptors, dry wells, mop sinks, leach pits, or the tailpiece of plumbing fixtures. An individual condensate drain shall be trapped in accordance with the appliance manufacturer’s instructions or in accordance with Section 814.4.

    TABLE 814.3

    MINIMUM CONDENSATE PIPE SIZE

    For SI units: 1 ton of refrigerant = 3.52 kW, 1 inch = 25 mm

    For SI units: °C = (°F-32)/1.8

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    814.6 Condensate Waste from Air-Conditioning Coils. Where the condensate waste from air-conditioning coils discharges by direct connection to a lavatory tailpiece or to an approved accessible inlet on a bathtub overflow, the connection shall be located in the area controlled by the same person controlling the air-conditioned space. 814.7 Plastic Fittings. Female plastic screwed fittings shall be used with male plastic fittings and plastic threads.

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    CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

    CHAPTER 9 - VENTS

    (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 § 316.0 High relevance — show source text

    INCREASERS AND REDUCERS . . . . . . . . . . . . . . . .316.0

    INDIRECT-FIRED WATER HEATERS . . . . . . . .211.0, 505.4,

    603.5.4, 608.7 INDIRECT WASTE . . . . . . . . . . . . . . . . . . . . . . . .Chapter 8 Air gap or break . . . . . . . . . . . . . . . . . . . . . . . . . . .801.2 Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .807.0 Approval required . . . . . . . . . . . . . . . . . . . . . . . . .802.0 Aspirators . . . . . . . . . . . . . . . . . . . . . . .603.5.9, 1303.5

    Chemical wastes . . . . . . . . . . . . . . . . . . . . . . . . . .811.0

    Cleanouts . . . . . . . . . . . . . . . . . . . . . . . . .801.3.2, 803.3

    Clear water wastes . . . . . . . . . . . . . . . . . . . . . . . .812.0

    Condensate . . . . . . . . . . . . . . . . . .814.1, 814.1.1, 814.5 Food handling fixtures . . . . . . . . . . . . . . . . . . . . .801.3.3 High temperature discharge . . . . . . . . . . . . . . . . .810.1 Interceptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .902.1 Receptors . . . . . . . . . . . . . . . . . . . . . . . . . .801.4, 804.0 Sterile equipment . . . . . . . . . . . .801.6, 806.0, 1303.4.1 Swimming pools . . . . . . . . . . . . . . . . . . . . . . . . . .813.0 Traps . . . . . . . . . . . . . . . . . . . . . . .801.3.2, 803.3, 814.5

    Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .803.3

    Where required . . . . . . . . . . . . . . . . . . . . . . . . . . .801.2

    INDIVIDUAL VENTS . . . . . . . . . . .211.0, Table 703.2, 904.1,

    908.2.1

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    INDEX

    INDUSTRIAL WASTES

  • CPC § 805.0 High relevance — show source text

    No standpipe receptor for a clothes washer shall extend more than 30 inches (762 mm), or not less than 18 inches (457 mm) above its trap weir. No trap for a clothes washer standpipe receptor shall be installed below the floor, but shall be roughed in not less than 6 inches (152 mm) and not more than 18 inches (457 mm) above the floor. No indirect waste receptor shall be installed in a toilet room, closet, cupboard, or storeroom, or in a portion of a building not in general use by the occupants thereof; except standpipes for clothes washers shall be permitted to be installed in toilet and bathroom areas where the clothes washer is installed in the

    same room.

    805.0 Pressure Drainage Connections. 805.1 General. Indirect waste connections shall be provided for drains, overflows, or relief vents from the water supply system, and no piping or equipment carrying wastes or producing wastes or other discharges under pressure shall be directly connected to a part of the drainage system.

    The preceding shall not apply to an approved sump pump or to an approved pressure-wasting plumbing fixture or device where the Authority Having Jurisdiction has been satisfied that the drainage system is adequately sized to accommodate the anticipated discharge thereof.

    806.0 Sterile Equipment.

    806.1 General. Appliances, devices, or apparatus such as stills, sterilizers, and similar equipment requiring water and waste and used for sterile materials shall be drained through an air gap.

    807.0 Appliances.

    807.1 Non-Classed Apparatus. Commercial dishwashing machines, silverware washing machines, and other appliances, devices, equipment, or other apparatus not regularly classed as plumbing fixtures, which are equipped with pumps, drips, or drainage outlets, shall be permitted to be drained by indirect waste pipes discharging through an air break into an approved type of open receptor.

    807.2 Undiluted Condensate Waste. Where undiluted condensate waste from a fuel-burning condensing appliance is discharged into the drainage system, the material in the drainage system shall be cast-iron, galvanized iron, plastic, or other materials approved for this use.

    Exceptions:

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

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

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

    808.0 Cooling Water.

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

  • CPC § 1.11.0. High relevance — show source text

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

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    CHAPTER 8

    INDIRECT WASTES

    801.0 General.

    801.1 Applicability. This chapter shall govern the materials, design, and installation of indirect waste piping, receptors, and connections; and provisions for discharge and disposal of condensate wastes, chemical wastes, industrial wastes, and clear water wastes.

    801.2 Air Gap or Air Break Required. Indirect waste piping shall discharge into the building drainage system through an air gap or air break as set forth in this code. Where a drainage air gap is required by this code, the minimum vertical distance as measured from the lowest point of the indirect waste pipe or the fixture outlet to the flood-level rim of the receptor shall be not less than 1 inch (25.4 mm). 801.3 Food and Beverage Handling Establishments. Establishments engaged in the storage, preparation, selling, serving, processing, or other handling of food and beverage involving the following equipment that requires drainage shall provide indirect waste piping for refrigerators, refrigeration coils, freezers, walk-in coolers, iceboxes, ice-making machines, steam tables, egg boilers, coffee urns and brewers, hot-and-cold drink dispensers, and similar equipment. 801.3.1 Size of Indirect Waste Pipes. Except for refrigeration coils and ice-making machines, the size of the indirect waste pipe shall be not smaller than the drain on the unit, but shall be not smaller than 1 inch (25 mm), and the maximum developed length shall not exceed 15 feet (4572 mm). Indirect waste pipe for ice-making machines shall be not less than the drain on the unit and in no case less than [3] ⁄ 4 of an inch (20 mm). 801.3.2 Walk-In Coolers. For walk-in coolers, floor drains shall be permitted to be connected to a separate drainage line discharging into an outside receptor. The flood-level rim of the receptor shall be not less than 6 inches (152 mm) lower than the lowest floor drain. Such floor drains shall be trapped and individually vented. Cleanouts shall be provided at 90 degree (1.57 rad) turns and shall be accessibly located. Such waste shall discharge through an air gap or air break into a trapped and vented receptor, except that a full-size air gap is required where the indirect waste pipe is under vacuum. 801.3.3 Food-Handling Fixtures. Food-preparation sinks, steam kettles, potato peelers, ice cream dipper wells, and similar equipment shall be indirectly connected to the drainage system by means of an air gap.

  • CPC § 2025 Medium relevance — show source text

    Chapter 7 Sanitary Drainage.

    This chapter regulates the design and installation of sanitary drainage systems to ensure they will work as intended. Drainage piping should not be oversized nor undersized, and constructed of approved materials to guard against fouling, deposit of solids, clogging, and with cleanouts so arranged that the pipes may be readily cleaned. The purpose of the sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment to an approved point of disposal, such as a public sanitary system or private sewage disposal system.

    The basics of a sanitary drainage system include public and private sewage disposal; selection of materials; installation of the building drain and sewer; joining methods for pipe and fittings; drainage fixture units for sizing the drainage system; sumps and ejectors; vent sizing and length of vents; and testing.

    Chapter 8 Indirect Wastes.

    Chapter 8 regulates indirect waste connections that are required for plumbing fixtures and plumbing appliances dealing with food preparation, dishwashing, potable liquids, and similar equipment. An indirect connection prevents sewage from backing up into a fixture or appliance, thus providing protection against potential health hazards. The waste pipe discharges through an air gap or air break into a waste receptor or standpipe. The protection in the form of an air gap is necessary when the contamination is a potential health hazard or cross connection with the potable water system. Where there is no possibility of contaminating the potable water (nonpotable discharge), the indirect waste pipe may connect in the form of an air break. This method is often preferred to prevent splashing. In addition, health care facilities and special wastes must be protected from contamination that may result from the connection to the drainage system. The waste must be treated to prevent any damage to the piping or sewage treatment process. Waste receptors are sized and designed to prevent splashing and allow for peak discharge conditions.

    Chapter 9 Vents.

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

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  • CPC § 601.0 Medium relevance — show source text

    Q 601.0 Water Supply. Q 601.1 General. Indoor horticulture water distribution systems shall be supplied with potable water in accordance with Chapter 6. Q 601.2 Materials. Pipe, tube, and fitting materials in contact with potable water, drinking water, or both shall be in accordance with Section 604.0.

    Q 601.3 Protection. Potable water piping used for irrigation purposes shall be equipped with an approved backflow prevention device or assembly in accordance with Table 603.2.

    Q 601.4 Alternate Water Supply. Where permitted, agricultural water may be used or alternate water sources in accordance with Appendix K.

    Q 701.0 Storage Tanks. Q 701.1 Construction. Where storage tanks are used, they shall be approved by the Authority Having Jurisdiction. Potable water storage tanks shall comply with Section 607.0. Rainwater catchment storage tanks shall comply with Appendix K or in accordance with the Authority Having Jurisdiction.

    Q 801.0 Fertigation and Irrigation Equipment. Q 801.1 Installation. Nutrient tanks and irrigation equipment shall be installed in accordance with the manufacturer’s instructions. When connected to the potable water supply, tanks and irrigation equipment shall be located downstream of water storage tank and be protected by an approved backflow device or method in accordance with Table 603.2

    Q 801.2 Materials and Construction. The piping, components, and devices shall be compatible with the additives or nutrients used. Above grade storage tanks shall be of an opaque material, approved for aboveground use in direct sunlight, or shall be shielded from direct sunlight.

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    APPENDIX Q

    Q 901.0 Sanitary Drainage and Indirect Wastes. Q 901.1 General. Sanitary drainage shall be in accordance with Chapter 7. Indirect wastes shall be in accordance with Chapter 8. The drainage system shall be compatible with the discharge liquid waste.

    Q 901.2 Hazardous Materials. Hazardous materials shall not be discharged into the sanitary sewer, storm drain, or on the ground. Q 901.3 Agricultural Water Waste. Agricultural water shall be discharged in accordance with the local, state, and federal regulations as approved by the Authority Having Jurisdiction. Where agricultural water discharges to the outdoors, and is not connected to the sanitary sewer, the piping shall be installed as to restrict rodents or vermin from entering the building. Q 901.4 Floor Drains, Floor Sinks, and Receptors. Wastewater shall discharge into an approved receptor. Receptors shall be compatible with the wastewater and installed in accordance with this code.

    Q 901.4.1 Plant Storage Areas. Where drains are provided in spaces where plants are stored, such drains shall be installed with indirect waste piping. Each indirect waste pipe from plant storage areas shall be separately piped to the indirect waste receptor and shall not combine with other indirect waste pipes.

    Q 1001.0 Facilities.

    Q 1001.1 Toilet Facilities. Toilet facilities shall be provided in accordance with the occupancy type.

    Q 1001.2 Location. Toilet facilities shall be located in such a manner to prevent contamination of plants during harvesting, holding, manufacturing/processing, and packing.

  • CPC § 3141B.1 Medium relevance — show source text

    3141B.1 General requirements. Material cleaned from filters and backwash water from any recirculation system shall be disposed in a manner that is acceptable to the local wastewater agency and will not create a nuisance. Backwash water shall not be returned to a pool. Pipes carrying wastewater from pools including pool drainage and backwash from filters shall be installed as an indirect waste in accordance with the requirements of Chapter 8 of the California Plumbing Code. Where a pump is used to discharge waste pool water to the drainage system, the pump discharge shall be installed as an indirect waste.

    3141B.2 Diatomaceous earth filters. The backwash from a diatomaceous earth filter shall discharge into a separation tank that has been installed to collect the waste diatomaceous earth mixture. The wastewater from the separation tank shall discharge into a sanitary sewer or other disposal system acceptable to the local wastewater agency.

    3141B.3 Piping. Sumps and drain piping shall have sufficient capacity to receive recirculation system backwash without overflow of the sump receiver. The sump shall not permit sewage to enter the surge basin or the pool in the event of a sewage backup

    3141B.4 Visual indicator. Where direct observation of the backwash discharge is not visible to the operator during backwash opera- tions, a sight glass shall be installed on the wastewater discharge line.

    3141B.5 Prohibited connection. There shall be no direct connection between the pool, its recirculation system or overflow drain to any sanitary sewer, storm drain or drainage system.

    SECTION 3142B—RESERVED

    SECTION 3143B—RESERVED

    SECTION 3144B—RESERVED

    SECTION 3145B—RESERVED

    SECTION 3146B—RESERVED

    SECTION 3147B—RESERVED

    SECTION 3148B—RESERVED

    SECTION 3149B—RESERVED

    SECTION 3150B—RESERVED

    SECTION 3151B—RESERVED

    SECTION 3152B—RESERVED

    SECTION 3153B—RESERVED

    SECTION 3154B—RESERVED

    SECTION 3155B—RESERVED

    SECTION 3156B—RESERVED

    31B-20 2025 CALIFORNIA BUILDING CODE

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

    PUBLIC POOLS

    SECTION 3157B—RESERVED

    SECTION 3158B—RESERVED

    SECTION 3159B—RESERVED

    Division II – PUBLIC SWIMMING POOLS

    Note: These building standards are in statute but have not been adopted through the regulatory process. Enforcement of these stan- dards set forth in this section does not depend upon adoption of regulations; therefore, enforcement agencies shall enforce the standards pursuant to the timeline set forth in this section prior to adoption of related regulations.

    SECTION 3160B—GROUND FAULT CIRCUIT INTERRUPTERS

  • CPC § 901.4.1 Medium relevance — show source text

    Q 901.4.1 Plant Storage Areas. Where drains are provided in spaces where plants are stored, such drains shall be installed with indirect waste piping. Each indirect waste pipe from plant storage areas shall be separately piped to the indirect waste receptor and shall not combine with other indirect waste pipes.

    Q 1001.0 Facilities.

    Q 1001.1 Toilet Facilities. Toilet facilities shall be provided in accordance with the occupancy type.

    Q 1001.2 Location. Toilet facilities shall be located in such a manner to prevent contamination of plants during harvesting, holding, manufacturing/processing, and packing.

    542 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 R - TINY HOUSES

    (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
    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 543

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

    544 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 R

    TINY HOUSES

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

    R 101.0 Tiny Houses.

  • CPC § 418.4 Medium relevance — show source text

    (3) Laundry rooms in commercial buildings and common laundry facilities in multi-family dwelling buildings. (4) Boiler rooms. 418.4 Food Storage Areas. Where drains are provided in storerooms, walk-in freezers, walk-in coolers, refrigerated equipment, or other locations where food is stored, such drains shall have indirect waste piping. Separate waste pipes shall be run from each food storage area, each with an indirect connection to the building sanitary drainage system. Traps shall be provided in accordance with Section 801.3.2 of this code and shall be vented.

    Indirect drains shall be permitted to be located in freezers or other spaces where freezing temperatures are maintained, provided that traps, where supplied, shall be located where the seal will not freeze. Otherwise, the floor of the freezer shall be sloped to a floor drain located outside of the storage compartment. 418.5 Floor Slope. Floors shall be sloped to floor drains.

    419.0 Food Waste Disposers. 419.1 Application. Food waste disposal units shall comply with UL 430. Residential food waste disposers shall also comply with ASSE 1008. 419.2 Drainage Connection. Approved wye or other directional-type branch fittings shall be installed in continuous wastes connecting or receiving the discharge from a food waste disposer. No dishwasher drain shall be connected to a sink tailpiece, continuous waste, or trap on the discharge side of a food waste disposer. 419.3 Water Supply. A cold water supply shall be provided for food waste disposers. Such connection to the water supply shall be protected by an air gap or backflow prevention device in accordance with Section 603.2.

    420.0 Sinks.

    420.1 Application. Sinks shall comply with ASME A112.19.1/CSA B45.2, ASME A112.19.2/CSA B45.1, ASME A112.19.3/CSA B45.4, CSA B45.5/IAPMO Z124, CSA B45.8/IAPMO Z403, or CSA B45.12/IAPMO Z402. Moveable sink systems shall comply with ASME A112.19.12. Sink assemblies with automatic soap dispensers, faucets, or hand dryers shall comply with IAPMO IGC 127. 420.2 Water Consumption. Sink faucets shall have a maximum flow rate of not more than 2.2 gpm at 60 psi (8.3 L/m at 414 kPa).

    Exceptions: (1) Clinical sinks (2) Laundry sinks (3) Service sinks

    420.2.1 Kitchen Faucets. [BSC-CG & DSA-SS] Kitchen faucets shall have a maximum flow rate of not more than 1.8 gallons (6.81 L) per minute at 60 psi (414 kPa). Kitchen faucets may temporarily increase the flow above the maximum rate, but not to exceed 2.2 gallons (8.3 L) per minute at 60 psi (414 kPa), and must default to a maximum flow rate of 1.8 gallons (6.81 L) per minute at 60 psi (414 kPa) in compliance with Chapter 5, Division 5.3 of the California Green Building Stan- dards Code (CALGreen). _**420.2.2 Kitchen Faucets.

Frequently asked questions

Do indirect waste receptors need to be accessible for cleaning?

Yes. The CPC requires receptors to be of such shape and capacity as to prevent splashing or flooding and to be readily accessible for inspection and cleaning (see § 804.1).

Can I install a clothes washer standpipe in a small closet?

Generally no — indirect waste receptors are prohibited in closets and storerooms. The single exception is standpipes for clothes washers may be installed in toilet and bathroom areas when the clothes washer is installed in the same room (see § 804.1).

When exactly do I need AHJ approval?

Before installing any plumbing fixture served by indirect waste pipes or receiving discharge therefrom — you must obtain AHJ approval first, per § 802.1.

Is an air gap always required at the receptor?

An air gap or air break is required where the code prescribes it for indirect waste piping; where an air gap is required the minimum vertical distance is 1 in (see § 801.2).

What is the allowable standpipe height for a clothes washer?

Standpipe for a clothes washer must not be less than 18 in nor more than 30 in above its trap weir, per § 804.1.

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