How to Fix a Running Toilet

Start With the Flapper

The rubber flapper at the bottom of the tank is a very common cause of a running toilet. Over time it can warp, crack, or stop sealing properly, letting water slowly leak from the tank into the bowl, which triggers the fill valve to keep topping the tank back up. Lift the tank lid and watch the flapper after a flush; if it does not sit flat and seal completely once the tank refills, that is likely your issue.

Check the Chain and Flush Handle

The chain connecting the flush handle to the flapper can cause the same symptom if it is too short (holding the flapper slightly open) or tangled (preventing a clean seal). This is one of the easiest and cheapest things to check before assuming a part needs replacing.

Check the Fill Valve and Float Height

If the flapper looks fine, the issue may be the fill valve, the part that refills the tank after a flush. If the float is set too high, water continuously trickles into the overflow tube instead of shutting off. Most fill valves have an adjustable float; lowering it slightly so the water level sits at the manufacturer's water-level mark, below the top of the overflow tube, often resolves this.

When It Is Not a Simple Fix

If you have checked the flapper, chain, and fill valve and the toilet still runs, the cause may be a cracked overflow tube, a worn-out fill valve that needs full replacement, or an issue with the tank-to-bowl seal. These are still generally straightforward repairs, but they are a good point to request a connection with a local provider rather than guessing further.

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