Why Is My Toilet Running Constantly? (And How to Fix It)

A toilet that runs constantly is wasting water — typically 200 gallons per day or more. That's roughly $50 to $100 per month added to your water bill, depending on your municipality's rates. It's also usually a simple fix.

The most common cause is a worn flapper. The flapper is the rubber seal at the bottom of the tank that controls water flow into the bowl. When it wears out, water seeps past it continuously, causing the fill valve to run to compensate. A replacement flapper costs about $5 at any hardware store and takes 10 minutes to install.

The second most common cause is a faulty fill valve. If the water level in the tank is above the overflow tube, the fill valve is either set too high or has failed. Adjusting the float arm or replacing the fill valve is a straightforward DIY repair.

A third cause is a cracked overflow tube. If the tube itself is cracked, water flows into the bowl continuously regardless of the flapper or fill valve. This requires replacing the flush valve assembly.

How to diagnose: put a few drops of food coloring in the tank. Don't flush. Wait 15 minutes. If color appears in the bowl, the flapper is leaking. If the water level in the tank is above the overflow tube, the fill valve is the issue.

Most running toilet repairs are DIY-friendly. If you've replaced the flapper and fill valve and the toilet is still running, call us at 313-427-4780. There may be a crack in the tank or a more complex valve issue that needs a plumber.