CPC · California Plumbing Code
When must water-distribution overflows/pressure drains be indirectly connected (air-gap requirements)?
If a tank, heater, boiler or other device is connected to the potable water distribution system, its overflow/relief must not be directly piped to the building drain — it must discharge through a water‑distribution air gap sized per Table 603.3.1 (see § 801.5). For drainage air gaps generally, the Code requires at least a 1‑inch vertical clearance to the receptor flood rim (see § 801.2). Consult Table 603.3.1 and your Authority Having Jurisdiction for the exact gap to install.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Indirect (non‑direct) waste connections are required for drains, overflows, or relief pipes from equipment that is connected to the potable water‑distribution system — for example pressure tanks, water heaters, boilers. The Code requires these discharges be made with a water‑distribution air gap constructed in accordance with Table 603.3.1. See § 801.5 for the primary rule.
The single most important rule: any overflow/relief from equipment that is on the potable water side must not be directly plumbed to the building drain — it must discharge through a properly sized water‑distribution air gap.
Requirements in detail
Basic obligations
- If the device is connected to the potable water distribution system, its overflow/relief/drain must be indirectly connected (i.e., not a direct hard piped connection) using a water‑distribution air gap. § 801.5 is the controlling section.
- The Code distinguishes drainage air gaps (Chapter 8) from water‑distribution air gaps (Chapter 6). For discharges required by Chapter 8, there is a minimum drainage air gap of 1 inch where a drainage air gap is required. § 801.2.
How to determine the required gap
- For water‑distribution overflows/relief drains specifically, the Code points you to the water‑distribution air gap dimensions in Table 603.3.1 (Chapter 6). The overflow must be constructed to meet the table. § 801.5; see also § 603.5.5 for acceptable protection methods to water‑supply inlets.
- If the Code requires a drainage air gap (Chapter 8), measure the vertical distance from the lowest point of the indirect waste pipe or fixture outlet to the flood‑level rim of the receptor — not less than 1 inch (25.4 mm). § 801.2.
Decision table (quick reference)
| Condition / discharge | Indirect connection required? | Air‑gap type or min. dimension to use | Code Reference |
|---|---|---|---|
| Overflows, drains, relief pipes from equipment connected to potable water distribution (pressure tanks, water heaters, boilers, etc.) | Yes | Water‑distribution air gap — construct per Table 603.3.1 | § 801.5 |
| Any indirect waste pipe where a drainage air gap is required | Yes | Minimum vertical gap 1 inch (25.4 mm) measured to the receptor flood‑level rim | § 801.2 |
| General pressure drainage / relief vents from the water supply system | Yes (no direct connection allowed) | Indirect connection required; exceptions only as noted in § 805.1 | § 805.1 |
| Food‑handling fixtures (sinks, ice machines, etc.) | Yes | Air gap (drainage) required; separate piping to receptor; length/size limits in § 801.3.1 | § 801.3.3, § 801.3.1 |
Note: The Code requires the water‑distribution air gap be “constructed in accordance with Table 603.3.1.” The actual gap dimensions in Table 603.3.1 were not included in the retrieved excerpts; consult Table 603.3.1 in Chapter 6 to get the exact dimension for your pipe size and installation.
Related installation limits and features
- Indirect waste piping sizing, length, and trap/vent rules for Chapter 8 discharges are set out in § 803.3 and related sections (e.g., max developed lengths, minimum pipe sizes, trapping).
- Standpipe receptors, mop sinks and other receptacles have location/height/shape requirements (Chapter 8, § 804.1).
Exceptions & special cases
- § 805.1 excludes certain approved devices from the general prohibition on direct connection: an approved sump pump or an approved pressure‑wasting plumbing fixture or device may be allowed if the Authority Having Jurisdiction (AHJ) is satisfied that the drainage system can safely handle the discharge. § 805.1.
- Some categories (sterilizers, food‑handling equipment, ice machines, condensate from HVAC, dishwashers) have their own specific indirect‑waste rules elsewhere in Chapter 8; those rules can add separate piping, maximum lengths, separation, or minimum pipe sizes. Examples: § 801.6 (sterilizers), § 801.3.3 (food‑handling).
If you need the exact vertical gap (inches or multiples of pipe diameter) for a water‑distribution air gap, you must consult Table 603.3.1 (Chapter 6). The machine excerpts we reviewed reference that Table but do not reproduce it.
Common mistakes
- Confusing an air break (drainage air break) with the water‑distribution air gap required where the discharge originates on the potable supply side — they are different protections and Chapter references. See § 801.2 and § 801.3.1.
- Piping an overflow directly into the building drain or trap without an air gap simply because the discharge seems “clean.” If the device is on the potable side the Code requires an indirect connection per § 801.5.
- Using a trap, check valve, or other device as a substitute for an air gap — mechanical devices do not meet the air‑gap requirement unless specifically allowed/listed by the Code or AHJ. See the requirement that these discharges be made using a water‑distribution air gap per § 801.5.
- Assuming the 1‑inch minimum drainage air gap (from § 801.2) always governs water‑distribution air gaps — for potable water discharges the Code points to Table 603.3.1, which may require larger clearances. Check the correct table/section.
Worked example — concrete scenario
Scenario: A potable‑water pressure tank in a small commercial building has an overflow relief pipe (1/2" nominal) that must discharge to a floor receptor.
Steps to apply the Code:
- Confirm the equipment is connected to the potable water‑distribution system → Code: indirect waste required. § 801.5.
- The Code calls for a water‑distribution air gap sized and constructed per Table 603.3.1 (Chapter 6). You must consult Table 603.3.1 to find the required unobstructed vertical distance for a 1/2" (or whatever) discharge. § 801.5.
- For drainage air gaps generally, measure the vertical distance from the lowest point of the overflow discharge to the flood‑level rim of the receptor; any drainage air gap required by Chapter 8 must be at least 1 inch. If the applicable protection is the drainage air gap in Chapter 8, the 1‑inch minimum applies (but remember the water‑distribution air gap may be larger per Table 603.3.1). § 801.2.
Because the retrieved code excerpts do not include the numeric entries from Table 603.3.1, you must look up Table 603.3.1 in Chapter 6 to obtain the exact gap for a 1/2" overflow. If the table specifies, for example, a gap of “X × diameter” or a fixed value, install that unobstructed vertical distance between the overflow outlet and the receptor flood rim. (If the AHJ approves a listed vacuum breaker or other listed device in lieu of the gap, that is an alternate only where the Code and AHJ permit — see § 603.5.5 for allowed water‑supply protection methods.)
Related provisions (quick list)
- § 801.2 — Air gap / air break required; minimum 1 inch drainage air gap.
- § 801.3.1 — Size/length limits for indirect waste pipes (food & beverage equipment).
- § 801.3.3 — Air gap requirements for food‑handling fixtures and ice storage.
- § 801.6 — Sterilizers: required indirect connection by air gap; separate piping rules.
- § 803.3 — Indirect waste piping sizing/length/trap/vent requirements.
- § 804.1 — Indirect waste receptors (standpipe, location, heights).
- § 805.1 — Pressure drainage connections; no direct connection allowed for water supply system drains/overflows/relief vents (exceptions for approved sump pumps and approved pressure‑wasting fixtures if AHJ approves).
- § 603.5.5 — Acceptable protection for water supply inlets (air gap, listed vacuum breaker with specified critical level, or backflow preventer).
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
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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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.
CPC § 801.3.1 High relevance — show source text
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. Bins, sinks, and other equipment having drainage connections and used for the storage of unpackaged ice used for human ingestion, or used in direct contact with ready-to-eat food, shall be indirectly connected to the drainage system by means of an air gap. Each indirect waste pipe from foodhandling fixtures or equipment shall be separately piped to the indirect waste receptor and shall not combine with other indirect waste pipes. 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).
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 § 403.4.5 High relevance — show source text
E 403.4.5 Discharge Water to Drain. Where discharge water is not recovered for reuse, the sump overflow line shall not be directly connected to a drain. Where the discharge water is discharged into a sanitary drain, an air gap of not less than 6 inches (152 mm) shall be provided between the termination of the discharge line and the drain opening. The discharge line shall terminate in a location that is visible to the building owner, tenants, or maintenance personnel.
E 403.5 Use of Reclaimed (Recycled) and Onsite Treated Nonpotable Water for Cooling. Where approved for use by the water or wastewater utility and the Authority Having Jurisdiction, reclaimed (recycled), or onsite treated nonpotable water shall be permitted to be used for industrial and commercial cooling or air-conditioning.
E 403.5.1 Drift Eliminator. A drift eliminator shall be utilized in a cooling system, utilizing alternate sources of water, where the aerosolized water is capable of coming in contact with employees or members of the public.
E 403.5.2 Disinfection. A biocide shall be used to treat the cooling system recirculation water where the recycled water is capable of coming in contact with employees or members of the public.
E 501.0 Heating, Ventilation, and Air-Conditioning Systems and Equipment – Energy Efficiency. E 501.1 Scope. The provisions of this section shall establish the means of enhancing energy efficiency associated with mechanical systems in a building.
E 502.0 Heating, Ventilation, and Air-Conditioning Low-Rise Residential Buildings. E 502.1 General. The heating, ventilating, air-conditioning, for single-family houses, multi-family structures not exceeding three stories above grade, and modular houses shall be in accordance with Section E 502.2 through Section E 502.12. The heating, ventilation, and air-conditioning system of other buildings shall be in accordance with Section E 503.0. E 502.2 Heating, Ventilating, and Air-Conditioning Systems and Equipment. This section shall regulate only equipment using single-phase electric power, air conditioners, and heat pumps with rated cooling capacities less than 65 000 British thermal units per hour (Btu/h) (19 kW), warm air furnaces with rated heating capacities less than 225 000 Btu/h (66 kW), boilers less than 300 000 Btu/h (88 kW) input, and heating-only heat pumps with rated heating capacities less than 65 000 Btu/h (19 kW). [ASHRAE 90.2:6.2] E 502.2.1 Nonresidential Type Systems and Equipment. Heating, ventilating, and air-conditioning systems and equipment that do not fall under the requirements of Section E 502.0 shall be in accordance with the applicable requirements of Section E 503.0. E 502.3 Balancing. The air distribution system design, including outlet grilles, shall provide a means for balancing the air distribution system unless the design procedure provides a system intended to operate within plus or minus 10 percent of design air quantities. [ASHRAE 90.2:6.3] E 502.3.1 Balancing Dampers. Balancing dampers shall be installed in branch ducts, and the axis of the damper shall be installed parallel to the direction of airflow in the main duct.
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 § 805.0 Medium 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 § 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 § 814.3.1 Medium 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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INDIRECT WASTES
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 § 2025 Medium relevance — show source text
An acceptable air supply for combustion and ventilation is necessary for the proper operation of fuel-burning appliances. A shortage of combustion air can result in incomplete combustion and the production of poisonous gases, such as carbon monoxide or appliance overheating. Ventilation air provides cooling for the appliance casing and internal controls. Inadequate ventilation of the space in which an appliance is installed can result in increased surrounding temperatures that stress the appliance itself or other appliances in the vicinity.
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FORMAT OF THE UNIFORM PLUMBING CODE
Chapter 6 Water Supply and Distribution.
Chapter 6 regulates the design, material, and installation of water supply and distribution systems, including residential fire sprinklers. The water supply and distribution system is designed to achieve the correct water pressure and flow rates and avoid cross-connections. For fixtures to perform properly, an acceptable supply of potable water is essential to their operation and use. Cross-connections and backflow are ranked as the highest priority because of the long history of recognized health risks posed by cross-connections, outbreaks, or cases of waterborne disease. Piping materials and components are evaluated for their possible effect on the potable water with which they are in contact. The intent is to control the potential adverse health effects produced by indirect additives, products, and materials that come in contact with potable water. When selecting materials for water supply and distribution systems, consider water pressure, water temperature, compatibility with the water supply, durability, support, and sustainability.
In addition, this chapter regulates the design, location, materials, and installation of multipurpose and stand-alone sprinkler systems that do not include the use of antifreeze. Where systems are installed as a portion of the water distribution system under the requirements of this chapter and are not provided with a fire department connection, backflow protection for the water supply system is not required.
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.
CPC § 807.2 Medium relevance — show source text
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.
809.0 Drinking Fountains.
809.1 General. Drinking fountains shall be permitted to be installed with indirect wastes through an air break.
810.0 Steam and Hot Water Drainage Condensers and Sumps.
810.1 High-Temperature Discharge. No steam pipe shall be directly connected to plumbing or drainage system, nor shall water having a temperature above 140°F (60°C) be discharged under pressure directly into a drainage system. Pipes from boilers shall discharge by means of indirect waste piping as determined by the Authority Having Jurisdiction or the boiler manufacturer’s recommendations. Such pipes shall be permitted to be indirectly connected by discharging into an open or closed condenser or an intercepting sump of an approved type that will prevent the entrance of steam or such water under pressure into the drainage system. Closed condensers or sumps shall be provided with a vent that shall be taken off the top and extended separately, full size above the roof. Condensers and sumps shall be properly trapped at the outlet with a deep seal trap extending to within 6 inches (152 mm) of the bottom of the tank. The top of the deep seal trap shall have a [3] ⁄ 4 of an inch (19.1 mm) opening located at the highest point of the trap to serve as a siphon breaker. Outlets shall be taken off from the side in such a manner as to allow
a waterline to be maintained that will permanently occupy not
182 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
INDIRECT WASTES
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
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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 § 2-5 Medium relevance — show source text
[RB] ADDITION. An extension or increase in floor area, number of stories or height of a building or structure.
[RB] ADHERED STONE OR MASONRY VENEER. Stone or masonry veneer secured and supported through the adhesion of an approved bonding material applied to an approved backing.
AGED HOME OR INSTITUTION. A facility used for the housing of persons 65 years of age or older in need of care and supervision. (See defi- nition of “care and supervision.”)
[MP] AIR, OUTDOOR. Ambient air that enters a building through a ventilation system, through intentional openings for natural ventilation or by infiltration.
[MP] AIR, TRANSFER. Air moved from one indoor space to another.
[MP] AIR ADMITTANCE VALVE. A one-way valve designed to allow air into the plumbing drainage system where a negative pressure develops in the piping. This device shall close by gravity and seal the terminal under conditions of zero differential pressure (no flow conditions) and under positive internal pressure.
[MP] AIR BREAK (DRAINAGE SYSTEM). An arrangement where a discharge pipe from a fixture, appliance or device drains indirectly into a receptor below the flood-level rim of the receptor and above the trap seal.
[MP] AIR CIRCULATION, FORCED. A means of providing space conditioning utilizing movement of air through ducts or plenums by mechanical means.
[MP] AIR GAP, DRAINAGE SYSTEM. The unobstructed vertical distance through free atmosphere between the outlet of a waste pipe and the flood-level rim of the fixture or receptor into which it is discharging.
[MP] AIR GAP, WATER-DISTRIBUTION SYSTEM. The unobstructed vertical distance through free atmosphere between the lowest opening from a water supply discharge to the flood-level rim of a plumbing fixture.
2025 CALIFORNIA RESIDENTIAL CODE 2-5
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DEFINITIONS
[MP] AIR-CONDITIONING SYSTEM. A system that consists of heat exchangers, blowers, filters, supply, exhaust and return-air systems, and shall include any apparatus installed in connection therewith.
[RB] AIR-IMPERMEABLE INSULATION. An insulation having an air permeance equal to or less than 0.02 L/s-m [2] at 75 Pa pressure differential as tested in accordance with ASTM E283 or E2178.
[RB] ALTERATION. Any construction, retrofit or renovation to an existing structure other than repair or addition that requires a permit. Also, a change in a building, electrical, gas, mechanical or plumbing system that involves an extension, addition or change to the arrangement, type or purpose of the original installation that requires a permit.
[RB] ALTERNATING TREAD DEVICE. A device that has a series of steps between 50 and 70 degrees (0.87 and 1.22 rad) from horizontal, usually attached to a center support rail in an alternating manner so that the user does not have both feet on the same level at the same time.
[RB] ANCHORED STONE OR MASONRY VENEER. Stone or masonry veneer secured with approved mechanical fasteners to an approved backing.
[MP] ANCHORS. See “Supports.”
Frequently asked questions
When the Code says “water‑distribution air gap,” is that the same as the 1‑inch gap in Chapter 8?
Not necessarily. Chapter 8 defines a minimum drainage air gap of 1 inch where a drainage air gap is required (§ 801.2). A water‑distribution air gap called out in § 801.5 must be constructed per Table 603.3.1 (Chapter 6), which may specify different dimensions. Consult Table 603.3.1 for the correct value.
Can I use a trap or check valve instead of an air gap for a potable‑water overflow?
No. The Code requires an indirect connection using a water‑distribution air gap for overflows/drains/relief pipes from equipment connected to the potable water distribution system (§ 801.5). Mechanical devices are not substitutes unless specifically permitted and listed/approved.
What if my building drain is large enough — can the overflow be directly connected if AHJ agrees?
§ 805.1 allows limited exceptions (e.g., approved sump pumps or approved pressure‑wasting fixtures) only where the Authority Having Jurisdiction is satisfied the drainage system can handle the discharge. Otherwise, indirect connections are required. § 805.1.
Where do I find the exact vertical gap I must install for a potable‑water overflow?
The Code points you to Table 603.3.1 in Chapter 6 for the water‑distribution air gap dimensions required for potable‑water discharges (as stated in § 801.5). The excerpts provided here reference that table but do not reproduce it; consult the live CPC text or your AHJ.
If equipment is not connected to potable water, do I still need an air gap?
If the discharge is non‑potable and the Code determines there is no possibility of contaminating potable water, an air break (drainage air break) may be acceptable rather than a full potable water air gap, but the specific equipment rules in Chapter 8 apply (see §§ 801.2–801.3).
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
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