UPC 803: Indirect Waste Piping

Section 803 is titled Indirect Waste Piping:

803.0 Indirect Waste Piping

It sets the rules for the indirect waste pipe itself. Where it must be used, how it discharges, and how far it may run. The chapter opens with the general rule that these connections use an air gap or an air break. That requirement carries the heading 801.2 Air Gap or Air Break Required. This page is about the piping. For the receptor and appliance side of these rules, see indirect waste and the air break.

Both methods break the direct path, so sewer water cannot travel back up the pipe. They are not the same.

An air gap is a full open space between the waste pipe outlet and the flood-level rim of the receptor. Nothing touches. This is the stronger protection.

An air break lets the waste pipe run down into the receptor, but it must stop above the trap seal. Flow is still interrupted if the receptor backs up. The code says which method a given piece of equipment needs. See the air gap glossary entry for more.

The code calls out equipment tied to food, drinking water, and clean supplies. Common cases in a commercial kitchen or building include:

• Walk-in coolers and refrigeration drains
• Ice machines and ice bins
• Food-prep and produce sinks
• Steam tables and dishwashers
• Water-treatment and reverse-osmosis units

These must drain through indirect waste piping into a floor sink or other receptor, not tie straight to the sewer. Food and beverage businesses get extra rules, under a heading titled 801.3 Food and Beverage Handling Establishments.

Indirect waste piping is meant to be short and simple. A long, flat run can trap waste, grow slime, and turn sour. So the code limits the pipe under a subsection titled 803.3 Pipe Size and Length:

803.3 Pipe Size and Length

The pipe is also expected to drain by gravity, not sit level. The exact length limit is set by the code, so it is described here, not quoted. Keep the run short, sloped, and easy to clean.

If you run a restaurant, bar, or food business, your ice machine, prep sinks, and cooler drains must use indirect waste piping with the right air gap or air break. Getting it wrong is a code and health violation, and it risks contaminating food. For a common failure, see why a commercial kitchen drain keeps overflowing. To learn where this waste lands, see floor sink vs floor drain vs mop sink. If your kitchen also handles grease, see what size grease interceptor a restaurant needs.

UPC Section 803 is part of the Uniform Plumbing Code. IAPMO publishes it and holds the copyright, so only the section headings are shown here. The pipe length limits and which fixtures qualify are described in plain terms, not quoted. Phoenix enforces the 2024 UPC with local amendments. Read the section on the UPC viewer at UpCodes, review the official code at IAPMO, or confirm local amendments with the City of Phoenix Planning & Development Department at phoenix.gov/pdd.