Toilet Keeps Running? How to Stop It Yourself
Short answerA toilet that keeps running usually has a worn or misaligned flapper letting tank water leak into the bowl. If water is spilling into the overflow pipe instead, the fill valve is the problem. Shut off the water, check the chain, clean or replace the flapper, then adjust or replace the fill valve.
Safety first
- Turn the shutoff valve behind the toilet clockwise until it stops before you take parts out. If it will not close, use the main water shutoff for the house.
- Do not lean on or drop the tank lid. Porcelain breaks easily and the edges are sharp.
Likely causes
| Cause | How to tell | What fixes it |
|---|---|---|
| Worn or warped flapper | Water trickles into the bowl, or the toilet refills by itself every so often with no one flushing it. | Clean the flapper and the seat under it. If the flapper is more than 5 years old, replace it. |
| Chain too tight or tangled | The flapper does not sit flat after a flush. | Reset the chain so it has about 1/4 to 1/2 inch of slack. |
| Fill valve not shutting off | The water level keeps rising until it drains into the overflow pipe. | Lower the water level, clean debris from the valve, or replace the valve. |
| Damaged flush valve seat | A new flapper still leaks, and you can feel nicks or roughness on the rim under it. | Replace the flush valve, or call a plumber, since this usually means taking the tank off. |
What you need
- Replacement flapper that matches yours
- Food coloring
- Pencil
- Clean cloth
- Replacement fill valve, if needed
- Towel and bucket
How to fix it
- Find out which part is leaking. Lift the tank lid and look at the water level. If water is pouring into the overflow pipe, go to the fill valve step. If not, add a few drops of food coloring to the tank, wait 10 minutes without flushing, and look in the bowl. Color in the bowl means the flapper is leaking. Flush right after the test so the tank does not stain.
- Shut off the water and empty the tank. Turn the valve behind the toilet clockwise until it stops, then flush and hold the handle down to drain the tank.
- Check the chain and clean the flapper. Set the chain to about 1/4 to 1/2 inch of slack. Wipe slime off the underside of the flapper and the seat with a clean cloth. Run your finger around the seat and feel for nicks. Remove any chlorine tablets from the tank, because they can damage these parts.
- Replace the flapper if it is old or warped. Unhook the old flapper from the ears on the overflow pipe and take it, or a photo of it, to the store so you buy the right one. Hook on the new one, attach the chain, and center the flapper over the opening.
- Fix the fill valve if water reaches the overflow pipe. Lower the water level with the adjustment on the fill valve so it stops below the top of the overflow pipe. If it still runs, clean debris out of the valve following the maker's directions. If that fails, replace the valve.
- Turn the water on and test. Open the shutoff valve, let the tank fill, and flush twice. Repeat the food coloring test to confirm the leak is gone.
When to call a professional
- The shutoff valve is stuck or leaking.
- New parts did not stop the running, and the seat under the flapper is damaged.
- Water is on the floor around the toilet as well.
What it costs to have fixed
Toilet Replacement is estimated at $230 to $910 nationally. See your state
Common questions
Why is my toilet constantly running?
Most of the time the flapper is worn and lets water leak from the tank into the bowl, so the fill valve keeps topping the tank off. A fill valve that does not shut off is the next most common reason.
Why does my toilet run every few minutes when no one flushes it?
That is called ghost flushing. A slow flapper leak drops the tank level until the fill valve turns on for a moment. Clean or replace the flapper.
How much water can a running toilet waste?
EPA says household leaks can waste up to 180 gallons a week, and toilets are often the cause.
How often should a toilet flapper be replaced?
EPA suggests replacing it at least every five years, or sooner if it is warped or no longer seals.
How do I know if my toilet fill valve is bad?
Korky's test: flush, mark the refilled water line, shut off the supply valve and wait at least 25 minutes. If the level drops, a part in the tank is leaking, and where it stops points to the flapper, seal or flush valve. If the flapper seals but water keeps running after the tank is full, the fill valve or its float may be the problem. Source
Can I replace a toilet flush valve without removing the tank?
Often you can repair it without taking the tank off. Fluidmaster sells a no-tank-removal kit that rebuilds a worn 2-inch flush valve seat, but it will not fit low-profile one-piece toilets or toilets with 3-inch or canister flush valves. Source
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Last verified 2026-11-01
Sources
- EPA WaterSense: Fix a Leak Week — Worn flappers as a common cause, the food coloring test and its 10 minute wait, replacing flappers at least every five years, and bringing the old part to the store
- EPA WaterSense: Residential Toilets — Most toilet leaks come from worn flappers, which are inexpensive to replace; leaks can waste up to 180 gallons per week
- Fluidmaster: Leaking Toilet Flapper — Ghost flushing, the shutoff and pencil-mark test, 1/4 to 1/2 inch of chain slack, cleaning the flapper and seat, and damage from in-tank chlorine tablets
- Fluidmaster: The Little Guide Book of Toilet Repairs — Water rising into the overflow pipe points to the fill valve; debris in the valve; clean it first, then replace it
- Fluidmaster: How to Fix a Weak or Incomplete Toilet Flush — Setting the tank water level with the fill valve adjustment
General information, not professional advice. Conditions, codes and prices vary. Turn off power, gas or water before any work, and hire a licensed professional when in doubt. Cost figures are our estimates, not quotes.