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Toilet-Vent Problem

Q: The water in my toilet bowl keeps draining out on its own. How do I take care of this toilet repair?

Richard Trehewey holds a toilet

The water in my toilet bowl keeps draining on its own. What's going on?

—Ron Mielcarek, Littleton, Colo.


Richard Trethewey replies: When a toilet bowl can't hold water, the likely suspect is a clogged vent. Vents are pipes inside the walls of your house that connect to all the sink, toilet, and tub drains and lead to the outside, usually through the roof. These pipes keep the air pressure in the drain system perfectly equalized so that waste water can flow freely. If a vent is blocked, typically by debris falling inside it, water will either go down the drain slowly and noisily or be sucked out of the nearest fixture's trap. That's probably what's happening to your toilet.

The first thing to do is have a plumber clear the vent pipes by running a snake down the roof vent. If that doesn't solve the problem, he might be able to install an air-admittance valve to supply additional air to the vent system. This valve, which can fit inside a vanity cabinet, draws its air from inside the house every time water goes down the drain. Then it immediately seals shut to block sewer gases from coming in the house.


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