7.3 Indirect Wastes, Air Gaps and Air Breaks, Receptors, Standpipes, & Condensate (UPC Chapter 8)
Key Takeaways
A drainage air gap must be at least 1 inch from the lowest point of the indirect waste pipe to the receptor's flood-level rim (UPC 801.2).
Food and beverage equipment indirect wastes must be at least as large as the unit drain, not smaller than 1 inch, and not more than 15 feet long; ice makers not smaller than 3/4 inch (UPC 801.3.1).
A clothes washer standpipe must extend 18 to 30 inches above its trap, and the trap must be 6 to 18 inches above the floor, never below it (UPC 804.1).
Food-preparation sinks, steam kettles, potato peelers, dipper wells, and ice bins must drain indirectly through an air gap (UPC 801.3.3).
Condensate waste pipes slope at least 1/8 inch per foot; air-cooling coil drains are 3/4 inch up to 20 tons and 1 inch for 21 to 40 tons (UPC 814.1, Table 814.3).
Why Indirect Waste Exists
A direct drainage connection lets sewage back up into whatever is connected when the drain stops. An indirect waste breaks the connection so that contaminated water cannot flow backward into food, sterile goods, or potable equipment. Section 801.2 requires indirect waste piping to discharge through an air gap or air break, as the code specifies for each use.
| Term | UPC definition | Protection |
|---|---|---|
| Air gap, drainage | Unobstructed vertical distance through free atmosphere between the lowest opening of the waste pipe or fixture and the receptor's flood-level rim | Full separation. Minimum 1 inch where a drainage air gap is required (801.2) |
| Air break | A physical separation that may be a low inlet into the receptor | The pipe may extend below the rim, but not into a sealed connection |
Where an Air Gap Is Required
| Section | Equipment | Rule |
|---|---|---|
| 801.3.3 | Food-preparation sinks, steam kettles, potato peelers, ice cream dipper wells; bins and sinks storing unpackaged ice or in contact with ready-to-eat food | Air gap. Each piped separately to the receptor |
| 801.5 | Drains, overflows, and relief pipes from potable water pressure tanks, water heaters, boilers, and similar equipment | Water-distribution air gap per Table 603.3.1 |
| 801.6 and 806.1 | Stills, sterilizers, and equipment for sterile materials | Air gap; each pipe separate, not over 15 feet; receptor in the same room |
| 807.3 | Domestic dishwashers | Listed dishwasher air gap fitting, with its flood-level (FL) mark at or above the flood level of the sink or drainboard, whichever is higher. Washington's 414.3 also requires commercial dishwashers to discharge through an air gap |
Air Gap or Air Break
- 801.3 Food and beverage establishments: Refrigerators, refrigeration coils, freezers, walk-in coolers, iceboxes, ice makers, steam tables, egg boilers, coffee urns and brewers, drink dispensers, and similar equipment need indirect waste.
- 801.3.2 Walk-in coolers: Floor drains may connect to a separate drainage line discharging to an outside receptor whose flood rim is at least 6 inches below the lowest floor drain. The drains are trapped and individually vented, with cleanouts at 90° turns. They discharge through an air gap or air break, and a full-size air gap is required if the line is under vacuum.
- 801.4 Bar and fountain sinks: Where the trap cannot be vented, the sink discharges through an air gap or air break to a vented receptor, with no more than 5 feet of developed length.
- 801.7 Drip outlets on equipment not classed as plumbing fixtures discharge into an open receptor through an air gap or air break.
Sizing and Length of Indirect Waste Pipe
| Rule | Requirement |
|---|---|
| 801.3.1 Food equipment | At least the size of the unit's drain, not smaller than 1 inch, maximum developed length 15 feet |
| 801.3.1 Ice makers | At least the size of the unit's drain, not smaller than 3/4 inch |
| 803.3 General | Pipes under 15 feet: at least the fixture outlet size, never under 1/2 inch |
| 803.3 Traps | Indirect pipes more than 5 feet but less than 15 feet long are directly trapped; those traps need not be vented |
| 803.3 Cleanouts | Angles and changes of direction need cleanouts for flushing |
| 803.3 Vents | A vent from indirect waste piping may not combine with a sewer-connected vent; it runs separately outdoors |
Receptors and Standpipes (UPC 804.1)
- Receptors must be approved for the use, shaped to prevent splashing or flooding, and readily accessible for inspection and cleaning.
- No indirect waste receptor in a toilet room, closet, cupboard, or storeroom, or in any part of a building not in general use. Exception: a clothes washer standpipe may be in a bathroom where the washer is installed in the same room.
- Clothes washer standpipe: no more than 30 inches and no less than 18 inches above its trap.
- Standpipe trap: not below the floor, and roughed in 6 to 18 inches above the floor.
- Receptor size: Table 702.1 note 1 and Table 702.2(2) size receptors by the total drainage capacity of the fixtures that drain into them.
Other Discharges
- 805.1 Pressure drainage: Equipment producing wastes under pressure may not connect directly to the drainage system, except approved sump pumps and pressure-wasting fixtures where the drainage is adequately sized.
- 808.1 Cooling water: With AHJ permission, clean cooling water may enter the inlet side of a fixture trap through a funnel set at least 6 inches above the fixture's overflow rim.
- 810.1 Steam and hot water: No steam pipe may connect directly to drainage, and water over 140°F may not discharge under pressure directly into drainage. Boiler blowoff goes to an approved condenser or sump.
- 812.1 Clear water wastes: Expansion tanks, cooling jackets, sprinkler drains, and drip pans discharge through an indirect waste.
- 813.1 Swimming pools: Pool drainage and filter backwash are indirect wastes, and so is pump discharge to drainage.
- 811 Chemical wastes: Pretreat harmful wastes and use corrosion-resistant piping (CPVC, PP, PVDF, glass, high-silicon iron). No copper for chemical or industrial wastes. Chemical vents may not intersect other vents.
Condensate (UPC 814)
- 814.1: Collect condensate and discharge it to an approved fixture or disposal area. If it goes into the drainage system, it goes through an indirect waste pipe sloped at least 1/8 inch per foot (1%), of corrosion-resistant material, not smaller than the outlet. It may not drain over a public way.
- Table 814.3 (air-cooling coils): up to 20 tons, 3/4 inch; 21–40 tons, 1 inch; 41–90 tons, 1-1/4 inches; 91–125 tons, 1-1/2 inches; 126–250 tons, 2 inches.
- 814.2 Secondary protection where overflow could cause damage (other than to lay-in ceiling tiles) requires one of the following: a water-level device that shuts off the unit, an additional pan with a separate drain, a higher secondary drain connection in the primary pan, or an additional pan with a level switch. A secondary drain pipe is at least 3/4 inch and discharges where it is readily observed.
- 807.2: Undiluted condensate from condensing appliances needs cast-iron, galvanized, plastic, or other approved drainage materials.
A commercial kitchen's food-preparation sink is being connected to the drainage system. What does UPC 801.3.3 require?
An air break into any floor drain in the room
A direct connection with a vacuum breaker on the tailpiece
A direct connection through a trap and sanitary tee
An indirect connection through an air gap, piped separately to the receptor
Where must the trap for a clothes washer standpipe be located under UPC 804.1?
Not below the floor, roughed in 6 to 18 inches above the floor, with the standpipe 18 to 30 inches above the trap
At floor level, with a 12-inch standpipe
Anywhere, if a vent is provided
Below the floor, with the standpipe 42 inches above the trap
An ice machine in a restaurant drains to a floor sink 10 feet away. Under UPC 801.3.1 and 803.3, which installation complies?
A 1/2-inch indirect waste with no trap
An indirect waste at least the size of the unit drain and not smaller than 3/4 inch, directly trapped because it exceeds 5 feet, with no vent required on that trap
A 1-inch pipe hard-piped into the floor sink's tailpiece
A 3/4-inch pipe that combines its vent with the kitchen's sewer-connected vent
Sections you finish are checked off in the contents.