PlumbingUpdated October 23, 2026 · 5 min
Toilet Keeps Running: Common Causes and Repair Costs
A running toilet usually means water is escaping from the tank into the bowl or the fill valve cannot shut off. The problem can waste hundreds of gallons if left unresolved.
URGENCY
Routine—prompt if water reaches the floor
TYPICAL COST
$90–$350
Safe checks you can do now
- 1Remove the tank lid carefully and set it on a towel.
- 2Check whether the flapper settles flat after each flush.
- 3Make sure the lift chain has slight slack and is not caught beneath the flapper.
- 4Turn the toilet shutoff valve clockwise if water begins reaching the floor.
Common causes
Worn flapper
A distorted seal lets tank water continuously leak into the bowl.
Fill-valve fault
The valve may keep admitting water after the tank reaches its normal level.
Incorrect float level
A high float sends water into the overflow tube instead of shutting the valve.
Call a professional when
- The shutoff valve leaks or will not turn.
- Water appears around the toilet base or through the ceiling below.
- New tank parts do not stop the continuous refill cycle.
Related home repair guides
FIXAVUE provides general educational information, not a diagnosis or substitute for an on-site inspection. Call 911 for immediate danger.