Toilet keeps running: how to fix it

A running toilet can waste hundreds of gallons a day, and it often shows up first as a higher water bill. The good news is that the parts inside the tank are simple and cheap.

Take the lid off the tank and watch what happens after a flush.

Water runs into the overflow tube

The float is set too high. Adjust it down so the water stops about 1/2 inch below the top of the overflow tube, the level Fluidmaster recommends. If lowering the float does not stop the flow, the fill valve is worn; see our toilet fill valve replacement guide.

The tank refills every few minutes

The flapper is leaking. Clean the rim it seals against, or replace the flapper with one that matches your flush valve size; see our toilet flapper replacement guide.

The flapper does not close

The chain may be too short or caught under the flapper. Leave about 1/2 inch of slack so the flapper can seat fully.

The dye test

1. Put a few drops of food coloring in the tank.
2. Do not flush for 15 to 20 minutes.
3. If color appears in the bowl, water is leaking past the flapper or flush valve.

If a new flapper still leaks, the valve seat may be damaged; see our toilet flush valve replacement guide.

Running toilet and a high water bill

A toilet that runs constantly, or refills on its own, is one of the most common causes of an unexplained jump in the water bill. To confirm, turn off every fixture and watch the water meter. If it moves, close the toilet shutoff valves one at a time; if the meter stops, you found it. If the meter still moves, look for other leaks; see our water meter spinning with everything off guide.