Tank parts leave different clues
Toilet Runs Every Few Minutes: Flapper, Fill Valve, and Overflow Causes
When you ask, “Why does my toilet run every few minutes?” the tank is often losing water until the fill valve opens again. A worn flapper may leak into the bowl, while the chain can hold it slightly open.
Continuous running can instead point to a failed fill valve, high float setting, or water entering the overflow tube. Jeneral Plumbing compares the water level, flapper, flush valve, fill valve, and supply connection before defining toilet repair.


