How to Fix a Running Toilet in 15 Minutes

A Running Toilet Is a Leak You Can Hear

A toilet that runs constantly can waste hundreds of gallons a day, and in older Philadelphia and South Jersey homes still fitted with their original fixtures, it's one of the most common plumbing complaints we hear. The fix almost always lives inside the tank, involves no more than a few dollars in parts, and takes about 15 minutes. Tank water is clean, so don't be squeamish about reaching in.

Step-by-Step: How to Fix a Running Toilet

1. Remove the tank lid and watch a flush. Set the lid somewhere safe and flush. Watch whether the flapper at the bottom seals, whether the chain hangs up, and where the water level settles — this tells you which fix you need.
2. Adjust the flapper chain. A chain that's too tight holds the flapper open; too loose and it gets pinned underneath. Re-clip it so there's about a half inch of slack when the flapper is closed.
3. Clean or replace the flapper. Mineral deposits and worn rubber keep the flapper from sealing, letting water trickle into the bowl continuously. Wipe the flapper and its seat clean; if the rubber is stiff, warped, or leaves residue on your fingers, swap in a new one that matches your model.
4. Set the water level. If water spills into the overflow tube, the fill level is too high. Adjust the float — a screw or clip on most modern fill valves — so the water stops about an inch below the top of the overflow tube.
5. Check the fill valve and refill tube. A fill valve that hisses or cycles on and off is failing and should be replaced. Also make sure the small refill tube clips above the overflow tube rather than pushing down inside it, which can siphon the tank endlessly.

When to Call a Pro

Call a licensed plumber if the shutoff valve behind the toilet is corroded or won't turn — forcing a seized valve in an older rowhome can snap it and flood the bathroom. The same goes for a cracked tank, water pooling at the base of the toilet, or a toilet that runs even after you've replaced the flapper and fill valve, which can point to a damaged flush valve seat that requires pulling the tank.

While you have your plumbing hat on, a slow sink or tub is the other five-minute fix worth doing — our guide on how to unclog a drain covers it without chemical cleaners.