How to Repair a Toilet That Won't Stop Running

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A running toilet wastes water, and it's just plain annoying. It's one of the easiest things in the house to fix, though. You don't need any plumbing knowledge, and you don't need a chest full of tools.


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Figure Out Why the Toilet Won't Stop Running

When you lift the lid of the toilet tank and look inside, all should become clear. A quick inspection will probably reveal one of the following conditions:

  • The water level is too high, and water is spilling into the overflow tube.

  • The chain between the handle and the flapper is too short or it has gotten tangled somehow.

  • The flapper is in poor condition and is probably leaking. Rippling water in the bowl confirms this.


The toilet won't stop filling in any of these instances, and the "running" sound you hear is the sound of the fill valve. In some cases, you may hear a hissing sound, especially if the toilet has an older ballcock valve. That's also the sound of the fill valve, and the toilet won't stop hissing as long as that valve is operating.


The Tank Level Is Too High

A simple adjustment of the float should lower the water level in the tank. If the toilet has a ballcock, unscrew the ball or rotate the armature so the bend is facing the top of the tank. You adjust cup-style floats by adjusting the length of the rod between the float and the valve using a screwdriver or your fingers.


The float is properly adjusted when the water level is an inch below the top of the overflow tube. There should be a line on the tube to mark this level.

Older ballcock valves can be difficult to adjust because of internal rust and wear. If you can't adjust the water level, it's time to replace the fill valve.


The Chain Needs Adjustment

A poorly adjusted flapper chain is easy to spot. It may be so short that there is no slack at all when the flapper is down, or there may be so much slack that the chain has gotten wedged under the flapper. The toilet won't stop running until you fix it.

Adjust the chain length by disconnecting it from the hook attached to the flush handle. Lengthen or shorten it by the required number of links and reattach it.


The Flapper Is Leaking

Flappers live long, lonely lives in the bottom of toilet tanks, and they wear out. They also get moldy or covered in scale depending on the purity of the water. A worn-out flapper lets water seep through, which is why the toilet won't stop filling.

Replacing a flapper is easy, and replacements are inexpensive. You might not have to replace the flapper, though. Remove it, wash it in the sink and if it's scaly, soak it in vinegar, and it might be as good as new.


Water on the Floor

If you don't see anything wrong in the tank, and you notice water on the floor, the tank is probably leaking. That's not a good sign. It could mean the tank is cracked. If so, replacing the tank is the only safe option.

Trace the water to its source. You may find it leaking from the water supply connection on the bottom of the tank. You should be able to tighten this connection with a pair of locking pliers but if not, replace the supply hose.

If the water is coming from a crack in the tank, turn off the water, empty the tank and refrain from using the toilet until you replace the tank.