Homeowner guide · Plumbing

Toilet keeps running? How to fix it

A toilet usually runs because the flapper is worn and leaks water into the bowl, the flapper chain is too short or tangled, or the fill valve's float is set too high so water spills into the overflow tube. Lift the tank lid and check those three. Flappers and fill valves are cheap, common fixes; call a plumber if the tank or connections leak.

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Quick answer

Start here

1
Water spilling into the overflow tube?
2
Chain has a little slack?
3
Flapper sealing flat?
4
Dye test in the tank

Plain-English, no jargon

Do a dye test

Put a few drops of food coloring in the tank and don't flush for 15 minutes or so. If color shows up in the bowl, the flapper is leaking.

Fix the cause

Worn flapper: replace it with one that matches your toilet's flush valve size.
Chain too tight or tangled: adjust it so there's a little slack with the flapper closed.
Float too high: lower it so the water stops about an inch below the top of the overflow tube.
Fill valve that won't shut off: replace the fill valve.

Why it's worth fixing

A running toilet can waste a large amount of water every day, and it shows up on your water bill. Most fixes take less than an hour and cost little in parts.

FAQ

Common questions

Why does my toilet run every few minutes on its own?

That's called phantom flushing. Water is slowly leaking from the tank into the bowl, usually past a worn flapper, and the tank refills when the level drops.

Can a running toilet raise my water bill?

Yes. A constant leak runs day and night, so even a slow one adds up.

Should I call a plumber for a running toilet?

Many homeowners replace a flapper or fill valve themselves. Call a plumber if there's a leak at the floor or supply line, or the fix doesn't work.

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