Why Is My Toilet Running and How Do I Fix It

The Usual Suspects

• A worn flapper. The rubber seal at the bottom of the tank hardens and warps over time, letting water leak past it into the bowl.
• A bad flush valve seat. If the seat the flapper sits on is corroded or rough, even a new flapper won't seal properly.
• The float set too high. Water keeps filling past the overflow tube and constantly drains off, so the tank never stops refilling.
• A tangled or misadjusted chain. Too short and it holds the flapper open a crack, too long and it can get caught under the flapper.
• A cracked overflow tube. Less common, but water escaping through a crack looks and sounds exactly like a running toilet.

Quick Fixes You Can Try

• Check and adjust the chain first. It's free and takes thirty seconds, jiggle the handle and look at how much slack the chain has.
• Replace the flapper. A universal flapper costs about $10 at any hardware store and solves the problem more often than any other single fix.

When to Call a Plumber

• The fix doesn't hold. If a new flapper and a properly adjusted chain still don't stop the running, the flush valve seat itself is likely damaged.
• Your water bill keeps climbing despite the fix. That points to a leak somewhere you haven't found yet, worth a proper look before it gets worse.

Quick Answers