UPC 1007: Trap Seal Protection for Floor Drains

Section 1007 covers trap seal protection for floor drains. The concern is simple. A seldom-used floor drain gets no fresh water, so its trap seal evaporates over time. Once the water is gone, the trap is dry and open, and sewer gas flows freely into the building. That gas smells bad and can be unhealthy.

The code answers this with two kinds of protection. The first is an automatic trap seal primer, a small device that feeds a little water into the trap now and then to keep it topped off. The second is a barrier-type device that physically blocks the drain when no water is running, so it holds back gas even with a dry trap. Each type must meet a product standard:

Potable water supply trap seal primer valves shall comply with ASSE 1018.

The standards break down by device type. ASSE 1018 covers primers fed from the potable water supply. ASSE 1044 covers drainage-type primers, which reuse waste water from a nearby fixture like a lavatory. ASSE 1072 covers barrier-type trap seal protection devices, the kind that seal the drain without adding any water.

This rule shows up most in commercial and utility spaces. Think of a mechanical room, a restroom with a floor drain that rarely sees use, a walk-in cooler, or a storage area. These are the exact spots where a floor drain can sit dry for a long stretch. On new construction and tenant improvements, plan review will look for trap seal protection on floor drains that are not fed by regular use.

A dry trap is one of the most common causes of a mystery sewer smell in a building. The drain looks fine, but the seal is gone. That is why the code wants protection built in from the start, not added only after someone complains about the odor.

If your building has a floor drain that only smells when it has been quiet for a while, a dry trap is the likely cause. A quick test is to pour a bucket of water into the drain. If the smell fades, the trap was dry and needs a lasting fix. A licensed plumber can add a trap seal primer or a barrier device that meets the right ASSE standard, so the seal stays put on its own.

To learn the parts involved, see what a P-trap is and the trap primer glossary entry. If you are chasing an odor, read sewer gas smell in a commercial building. For related drain rules, see floor drain requirements and which fixture traps the code allows, or read why a floor drain backs up.

UPC Section 1007 is part of the Uniform Plumbing Code. IAPMO publishes and holds the copyright on it. The excerpt above reflects the section as adopted. Phoenix enforces the 2024 UPC with local amendments as part of its Building Construction Code. Read the current text on UpCodes and confirm local amendments through the City of Phoenix Planning & Development Department at phoenix.gov/pdd.