How to fix a running toilet
To fix a running toilet, lift the tank lid: if water is pouring into the tall open tube in the middle, the fill level is set too high, so turn the float adjustment down. If not, the rubber flapper at the bottom is leaking. Close the valve behind the toilet, flush to empty the tank, and replace the flapper with one the same size.
You wake to the toilet hissing and refilling on its own.
Why it matters: The hiss at 2 a.m. usually needs a part that costs less than lunch.
Steps
- Take off the tank lid and lay it on a towel, since it cracks easily.
- Find the mark on the tall overflow tube; water should stop below it.
- If water spills into the tube, turn the float's adjustment screw or clip so it shuts off lower.
- If the level is fine, the flapper is leaking: turn the valve behind the toilet clockwise to close it.
- Flush to empty the tank and unhook the flapper from its chain and its two side pegs.
- Take it to a hardware store to match the size, or check the size printed inside the tank.
- Fit the new flapper, clip the chain with a little slack, open the valve and listen.
Stop and call a professional if
- the valve behind the toilet will not close or leaks when you turn it
- water is leaking around the base of the toilet onto the floor: ask the landlord or a plumber
Common mistakes
- Ignoring a running toilet that quietly wastes water all month.
- Buying a flapper that does not match the drain size.
- Setting the chain so tight the flapper cannot seal.
Teach this to someone
A one page sheet for showing a friend, a teenager or a parent: what to say, what to show, and one question to check it landed.
Teach: How to fix a running toilet
What to say
To fix a running toilet, lift the tank lid: if water is pouring into the tall open tube in the middle, the fill level is set too high, so turn the float adjustment down. If not, the rubber flapper at the bottom is leaking. Close the valve behind the toilet, flush to empty the tank, and replace the flapper with one the same size.
What to show
- Take off the tank lid and lay it on a towel, since it cracks easily.
- Find the mark on the tall overflow tube; water should stop below it.
- If water spills into the tube, turn the float's adjustment screw or clip so it shuts off lower.
- If the level is fine, the flapper is leaking: turn the valve behind the toilet clockwise to close it.
- Flush to empty the tank and unhook the flapper from its chain and its two side pegs.
- Take it to a hardware store to match the size, or check the size printed inside the tank.
- Fit the new flapper, clip the chain with a little slack, open the valve and listen.
Where it stops
Stop and call a professional if the valve behind the toilet will not close or leaks when you turn it.
Check question
Where is the water supply valve for a toilet?
Answer: Behind the toilet on the wall or floor. Each toilet has its own small valve on the supply line behind it.
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Related skills
Sources
This skill is general practice and draws on no single published source.
Written in our own words from the sources above. It is general information, not advice for your situation; where a professional, your doctor or your lease says something different, follow them.
Last reviewed . First published .