Toilet Keeps Running? Here's What's Actually Wrong

A toilet that runs on after the flush is the most common plumbing complaint we take in Oklahoma, and it is also the one homeowners live with longest. It is not dramatic. Nothing floods. But a toilet that runs continuously can push 200 gallons a day through your meter, which shows up on the bill long before it shows up as a problem.

There are only three parts that cause it, and you can identify which one in about two minutes.

Test one: is water leaking into the bowl?

Take the tank lid off and put a few drops of food colouring into the tank water. Do not flush. Wait fifteen minutes and look in the bowl. If colour has appeared, water is leaking past the flapper at the bottom of the tank.

The flapper is a rubber seal that lifts when you flush and drops back to hold water in the tank. Rubber hardens, mineral deposits build on the seat, and eventually it stops sealing. In Oklahoma's hard water this happens faster than the packaging promises — three to five years is common.

Test two: is water running into the overflow tube?

If the colour test came back clean but you can see water trickling into the open vertical tube in the middle of the tank, the fill valve is not shutting off at the right level. Either the float is set too high, or the valve itself has failed.

Try bending or adjusting the float down so the water stops about an inch below the top of the overflow tube. If the water still creeps up past it, the fill valve needs replacing.

Test three: phantom flushing

If the toilet refills by itself every few minutes with nobody near it, that is a slow flapper leak — the tank is quietly emptying into the bowl until the float drops far enough to trigger a refill. Same fix as test one.

What it costs to fix

Flappers and fill valves are inexpensive parts. Most people can change a flapper themselves in fifteen minutes with the water shut off at the wall. Fill valves are slightly more involved because the tank has to be drained and the valve unbolted from underneath.

Where it is worth calling: if the tank keeps failing after new parts, if the shutoff valve at the wall will not turn or drips when you use it, or if there is water on the floor around the base — that is a different problem entirely, usually a failed wax ring. See our toilet repair page for what that involves.

When the toilet is not the real problem

A toilet that flushes weakly, gurgles, or rises before it drains is telling you about the drain, not the tank. If more than one fixture is slow at the same time, look at drain cleaning or, if the lowest drain in the house is the worst, a sewer line problem.

If you would rather not spend a Saturday on it, call (833) 435-9778. Toilet repairs are flat-priced and usually take under an hour.