Is there a sound worse than a toilet running at 2am? I listened to mine for two weeks with the bathroom door closed before I admitted the noise was not going to fix itself. It turned out to be a small part and a twenty minute job I had put off for way too long.

Find out which part is failing

A running toilet is almost always the flapper or the fill valve. The flapper is the rubber stopper at the bottom of the tank. When it wears out or sits crooked, water leaks from the tank into the bowl all night. Take the lid off and look: if water is moving into the bowl constantly, it is the flapper. If the tank is refilling even when you are not flushing, check the fill valve.

The flapper fix

Replacing a flapper takes five minutes:

1. Turn off the water valve behind the toilet and flush to empty the tank.
2. Unhook the old flapper from the chain and the little posts on the overflow tube.
3. Snap the new one on. Buy the same brand or a universal one, they are a few dollars at any hardware store.
4. Hook the chain back with about a quarter inch of slack. Too tight and the flapper will not seal. Too loose and it will not lift.

The chain length is the part everyone gets wrong. If your toilet starts running again after a flush, the chain is probably too tight and holding the flapper open.

When it is the fill valve

If the tank keeps filling, the fill valve is the problem. You can buy a universal fill valve kit and swap it in about thirty minutes. Turn off the water, disconnect the supply line, unscrew the old valve, and follow the new one’s instructions. The kit comes with everything and the hardest part is reaching behind the toilet.

A constantly running toilet can waste hundreds of gallons a month, which shows up on your water bill. Mine dropped noticeably the month after I fixed it, which turned a small annoyance into a small win.