Toilet Running Constantly: Common Causes and Fixes

A toilet that runs constantly—sometimes quietly, sometimes noticeably—doesn’t just waste water. It can also drive up utility bills and indicate a problem inside the tank that’s easy to miss during day-to-day use.

While the exact cause varies by model, most constant-running issues come from a component in the toilet tank failing to seal properly or being set incorrectly. Here are the most common reasons and practical fixes to restore normal flushing behavior.