Fix a running toilet
Start by lifting the tank lid. A toilet that keeps running or refills on its own often has a problem with the flapper, chain or fill valve. Checking those parts takes just a few minutes, and replacements are inexpensive. Tackling it now can save a lot of wasted water. The EPA says a running toilet can waste 200 gallons or more a day, often without making much of a sound.
How a toilet tank works
There isn't much in a toilet tank. A lets water in, a float tells it when to stop, and a rubber at the bottom holds the water until you flush. When a toilet keeps running, one of those three isn't doing its job, and a few quick checks with the lid off will tell you which.
What's usually wrong
Rubber gets stiff and warped with age. Water seeps past it into the bowl, the tank level drops, and the fill valve turns on to top it up. That's the refill you hear every so often. That steady cold refill can also make the tank sweat.
With no slack, the chain holds the flapper open a crack. With too much, it can get caught under the flapper.
Water rises until it spills into the , so the fill valve never gets the signal to stop.
If it keeps hissing with a good flapper and the water at the right level, the valve itself isn't closing.
| What you notice | Most likely | Fix |
|---|---|---|
| Refills by itself every so often | Flapper leaking | Replace the flapper. |
| Water runs into the overflow tube nonstop | Water level too high | Lower . |
| Constant hiss, level looks right | Fill valve worn | Replace the fill valve. |
| Runs until you jiggle the handle | Chain too long or caught | Shorten the chain to about half an inch of slack. |
| Weak flush, then runs | Chain too loose or low water | Adjust the chain and float. |
Stop the running
- Test with food coloringPut 5 to 10 drops of food coloring in the tank and leave it for 15 minutes without flushing. If color shows up in the bowl, water is getting past the flapper, and you can skip to step 4.
- Check the chainWith the flapper closed, the chain should have about half an inch of slack. Move the clip a link or two if it's too tight or too loose, then flush to test.
- Look at the water levelIf water is running into the overflow tube, the float is set too high. Turn the adjustment screw on top of the fill valve, or squeeze the clip and slide the float down, until the water sits about an inch below the top of the tube, or at the fill line marked inside the tank.
- Replace the flapperTurn off the valve behind the toilet and flush to empty the tank. Unclip the chain from the handle arm, unhook the old flapper from the two pegs on the sides, and snap the new one on. If the old one feels soft, warped or slimy, that was the problem.
- If it still hisses, replace the fill valveIf the tank keeps filling with a good flapper, the fill valve is worn. A universal replacement kit costs about $12 to $20, and the instructions on the box are clear.
- Refill and test againTurn the water back on, let the tank fill, and repeat the food coloring test. If the bowl stays clear after 15 minutes and the tank stays quiet, it's fixed.
Watch it done
- The bowl stays clear 15 minutes after the food coloring test
- The tank fills and then goes quiet
- Water sits about an inch below the top of the overflow tube
- No slow drop in the tank level between flushes
If it starts running again
Watch the tank right after a flush. If water keeps pouring into the overflow tube, look at the float and fill valve. If the level drops slowly with no sound, it's the flapper or the seat it sits on.
Run a finger around the rim the flapper closes against. If it's rough or pitted, even a new flapper won't seal. A flush valve repair kit adds a smooth new seat for about $15.
What a pro typically charges (a rough estimate; prices vary by area): A plumber typically charges $150–$300 to fix a running toilet, and most of that is the visit. The parts usually cost less than $25.
Find a plumber near you