A toilet that keeps running is easy to ignore, but it can send hundreds of gallons a day down the drain. The good news: the cause is almost always one of five inexpensive parts inside the tank.
1. A worn flapper
The rubber flapper at the bottom of the tank seals the flush valve. Over time it warps or hardens and lets water seep into the bowl. Put a few drops of food coloring in the tank and wait 15 minutes without flushing. Color in the bowl means the flapper leaks. Replacing it takes minutes.
2. A chain that is too short or tangled
If the chain holds the flapper slightly open, the tank never fills. Leave about half an inch of slack.
3. A float set too high
When the water level rises above the overflow tube, water runs down it constantly. Lower the float so the level sits about an inch below the top of the tube.
4. A failing fill valve
A fill valve that hisses, never fully shuts off or refills in bursts is worn out. It is a standard part and worth replacing rather than adjusting.
5. A cracked overflow tube or flush valve
This one needs the tank removed from the bowl. It is a job for a plumber unless you are comfortable with it.
When to call a plumber
If you have replaced the flapper and the toilet still runs, if the tank refills on its own every few minutes, or if there is water at the base, book toilet repair. If the toilet is old, cracked or clogs constantly, toilet replacement often costs less than repeated repairs. And if the toilet is overflowing right now, shut the valve behind it and call an emergency plumber.
Common questions
How much water does a running toilet waste?
A badly leaking toilet can waste 200 gallons or more per day, which shows up quickly on a water bill.
Can a running toilet overflow?
Normally no, because excess water goes down the overflow tube. If the drain is also clogged, it can.