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Gerald Edwards
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1 Chapter 9 Indirect Waste Piping and Special Wastes 9.1 INDIRECT WASTES General Drains from fixtures, fixture compartments, equipment, appliances, appurtenances, and other devices requiring protection against contamination from backflow or flooding from the drainage system or other source shall not be directly connected to any soil, waste, or vent pipe. Such drains shall discharge separately through an air gap or, where permitted, an air break Air Gaps The clear air gap between a drain outlet or indirect waste pipe and the flood level rim of an indirect waste receptor or other point of disposal shall be not less than twice the diameter of the effective opening of the drain served, but not less than one inch Air Breaks Where air breaks are permitted, the waste pipe shall be permitted to terminate below the flood level rim of the receptor but shall maintain an air space above the top of the receptor s trap seal. Such indirect waste pipes shall be permitted to connect to the inlet side of the receptor s trap Where Indirect Wastes Are Required Indirect wastes shall be provided for food-handling or food-storage equipment, medical or other sterile equipment, clear-water wastes or discharges, and other drains as required herein Food Handling Areas a. Fixtures and appliances used for the storage, processing, preparation, serving, dispensing, or sale of food shall be drained indirectly. Examples of such fixtures include refrigerated cases, steam kettles, dishwashing machines, culinary sinks and/or sink compartments used for rinsing, sanitizing, soaking or washing food, ice machines, ice storage bins, drink dispensers, and similar equipment or appliances. A separate indirect waste pipe shall be provided for each fixture and/or compartment drain and each shall discharge separately through an air gap or air break into a trapped and vented receptor. b. Where bar sinks, glass-washing sinks, or other counter sinks cannot be vented according to the requirements of Chapter 12, they shall be permitted to each discharge separately to a trapped and vented receptor through indirect waste pipes providing either an air break or an air gap National Standard Plumbing Code 115

2 EXCEPTIONS: (1) For multi-compartment commercial sinks, only the compartment used for washing pots, tableware, kitchenware, and utensils shall discharge to the drainage system through a grease interceptor in accordance with Sections and 6.2. (2) The rinsing and sanitizing compartments of multi-compartment commercial sinks shall be drained indirectly, in accordance with Section (3) If a properly vented floor drain is installed immediately adjacent to a sink used for washing, a properly trapped and vented sink or sink compartment shall be permitted to connect directly to the drainage system, on the sewer side of the floor drain trap. (4) Indirect drains shall not be required for domestic kitchen sinks or domestic dishwashers Walk-in Coolers and Freezers a. If floor drains are located in walk-in coolers or walk-in freezers used for the storage of food or other products for human consumption, they shall be indirectly connected to the sanitary drainage system. b. Separate indirect waste pipes shall be provided for the floor drains from each cooler or freezer, and each shall discharge separately through an air gap or air break into a trapped and vented receptor. c. Traps shall be provided in the indirect waste pipe when required under Section d. Indirectly connected floor drains may be located in freezers or other spaces where freezing temperatures are maintained, provided that traps are not required under Section Otherwise, the floor of the freezer shall be sloped to a floor drain located outside the storage compartment. e. The above requirements do not apply to refrigerated food preparation areas or work rooms Medical and Other Sterile Equipment Stills, sterilizers, and other sterile equipment requiring drainage shall each discharge separately through an air gap into a trapped and vented receptor Potable Clear-Water Wastes Discharges of potable water from the water distribution system, water storage or pressure tanks, water heaters, water pumps, water treatment equipment, boilers, relief valves, backflow prevention devices, and other potable water sources shall be indirect through an air gap. EXCEPTION: An air break shall be permitted where the potable water supply to boilers, water-cooled equipment, heating and air-conditioning systems, and similar cross-connections is protected by a backflow prevention device in accordance with Section Drinking Fountains and Water Coolers Drinking fountains and water coolers shall be permitted to discharge indirectly through an air break or air gap. Where such fixtures are connected to a dedicated drainage stack, the fixtures may connect directly to the stack and the stack shall terminate with an air break or air gap Air Conditioning Equipment Where condensate or other drainage from air conditioning or cooling equipment discharges to a drainage system, it shall discharge indirectly to a trapped and vented receptor through an air break or air gap. EXCEPTION: An air break shall not be permitted where the drain connects to a point in the air conditioning equipment that operates at a pressure below atmospheric Swimming Pools Drainage from swimming pools or wading pools, including pool drains, filter backwash, overflows, and pool deck drains, shall discharge indirectly through an air gap to a trapped and vented receptor National Standard Plumbing Code

3 Relief Valve Discharge Piping Discharge piping from relief valves and any associated indirect waste piping shall be in accordance with Section INDIRECT WASTE PIPING Materials and Installation Indirect waste piping shall be of materials approved for sanitary drainage under Section Pipe Size Indirect waste piping shall be not less than the nominal size of the drain outlet on the fixture or equipment served Fixture Traps Traps shall be provided at fixtures and equipment connections where the developed length of indirect waste piping exceeds ten feet. EXCEPTION: Drain lines used for clear-water wastes Provisions for Cleaning Indirect waste piping shall be installed in a manner to permit ready access for flushing and cleaning. Where necessary, cleanouts shall be provided in accordance with Section INDIRECT WASTE RECEPTORS General a. Receptors for indirect wastes shall be properly trapped and vented floor drains, floor sinks, standpipes, open-hub drains, air gap fittings, or other approved fixtures. b. Receptors shall be of such size, shape, and capacity as required to prevent splashing or flooding by the discharge from any and all indirect waste pipes served by the receptor. c. Plumbing fixtures that are used for domestic or culinary purposes shall not be used as receptors for indirect wastes, except as follows: EXCEPTIONS: 1) In a dwelling unit, a kitchen sink trap, or food waste grinder, shall be permitted to receive the discharge from a dishwasher. (2) In a dwelling unit, a laundry sink, provided that an air gap is maintained for any potable clear-water waste, shall be an acceptable receptor for: a. Air conditioning condensate. b. Automatic clothes washer. c. Water treatment unit. d. Water heater relief valve discharge. (3) A service sink or mop basin shall be an acceptable receptor for air conditioning condensate and any infrequent potable clear-water waste if the required air gap is provided for potable clear-water wastes Strainers or Baskets Floor sinks and floor drains that handle other than clear-water wastes shall include an internal or a removable metal basket to retain solids National Standard Plumbing Code 117

4 9.3.3 Prohibited Locations Receptors for indirect wastes shall not be located in a toilet room or in any confined, concealed, inaccessible, or unventilated space. EXCEPTION: Air conditioning condensate in dwellings shall be permitted to drain to a tub waste and overflow or lavatory tailpiece in accordance with Section c Standpipes A standpipe, 2-inch minimum pipe size and extending not more than 48 inches nor less than 18 inches above its trap, shall be permitted to serve as a receptor for a domestic clothes washer. In a dwelling, a laundry sink shall be permitted to drain into the standpipe Open-hub Drains A trapped and vented open-end drain pipe extending not less than 2 inches above the surrounding floor shall be permitted to serve as a receptor for clear-water wastes Minimum Receptor Pipe Size a. The minimum drain pipe size for an indirect waste receptor shall be at least one pipe size larger than the indirect waste pipe that it serves. EXCEPTION: A laundry sink receiving the discharge from an automatic clothes washer under Section c(2).b. b. Where a receptor receives indirect drainage from two or more fixtures, the cross-sectional area of the receptor drain shall be not less than the aggregate cross-sectional area of all indirect waste pipes served by the receptor. For the purposes of this requirement, 1-1/4" pipe = 1.2 in 2, 1-1/2" pipe = 1.8 in 2, 2" pipe = 3.1 in 2, 2-1/2" pipe = 4.9 in 2, 3" pipe = 7.1 in 2, 4" pipe = 12.6 in 2, 5" pipe = 19.6 in 2, and 6" pipe = 28.3 in Drainage Fixture Unit (DFU) Values The drainage fixture unit values used to combine the loading of indirect waste receptors with other fixtures shall be the sum of the DFU values for all fixtures that are indirectly drained into the receptor. 9.4 SPECIAL WASTES Treatment of Corrosive Wastes Corrosive liquids, spent acids, or other harmful chemicals that may damage a drain, sewer, soil or waste pipe, create noxious or toxic fumes, or interfere with sewage treatment processes shall not be discharged into the plumbing system without being thoroughly neutralized or treated by passing through a properly constructed and approved neutralizing device. Such devices shall be provided automatically with a sufficient supply of neutralizing medium, so as to make its contents non-injurious before discharge into the drainage system. The nature of the corrosive or harmful waste and proposed method of its treatment shall be submitted to and approved by the Authority Having Jurisdiction prior to installation High Temperature Wastes No waste at temperatures above 140 F shall be discharged directly into any part of a drainage system. Such wastes shall be discharged to an indirect waste receptor and a means of cooling shall be provided where necessary National Standard Plumbing Code

5 9.4.3 Air Conditioning Condensate a. Indirect waste piping from air conditioning units shall be sized according to the condensate-generating capacity of the units served. Branches from individual units shall be no smaller than the drain opening or drain connection on the unit. Traps shall be provided at each air conditioning unit or cooling coil to maintain atmospheric pressure in the waste piping. b. Condensate waste piping shall be sloped not less than 1/8" per foot. Drainage fittings shall be used in sizes 1-1/4" and larger. Minimum pipe sizing shall be as follows: 3/4" pipe size through 3-ton cooling capacity 1" pipe size through 20-ton cooling capacity 1-1/4" pipe size through 100-ton cooling capacity 1-1/2" pipe size through 300-ton cooling capacity 2" size pipe through 600-ton cooling capacity c. Discharge of air conditioning condensate shall not be permitted to create a nuisance such as by flowing across the ground or paved surfaces. Unless expressly prohibited by the Authority Having Jurisdiction, the point of indirect discharge for air conditioning condensate shall be one of the following: 1. The building sanitary drainage system. 2. The building storm drainage system. 3. A sump pump. 4. A subsurface absorption pit or trench. 5. Within dwellings, a tub waste and overflow or lavatory tailpiece within the same dwelling National Standard Plumbing Code 119

c. Direct or indirect?

c. Direct or indirect? ~ \ 1.) GENERAL a. Definitions: Chapter B Code References (1) Air-break Comm 81.01 (5) (2) Air-gap, drain system Comm 81.01 (6) (3) Flood level rim Comm 81.01(102) (4) sink Comm 81.01(105) (5) Indirect