Tools You'll Need
Step-by-Step
Check the water level
Remove the tank lid. The water should stop about an inch below the top of the overflow tube. If it's above the overflow tube, the fill valve isn't shutting off properly.
Watch the overflow tube
If water is continuously running into the overflow tube, the fill valve is not shutting off. It needs adjustment or replacement.
Adjust the float
On older fill valves, turn the adjustment screw to lower the float. On newer ones, pinch the clip on the side and slide the float down. The water should stop below the overflow tube.
Check for mineral buildup
If the fill valve is slow or makes noise, mineral buildup may be restricting it. Some can be cleaned; others need replacement.
Listen for phantom refills
If the toilet refills on its own every few minutes, suspect a slow tank-to-bowl leak first — commonly at the flapper/flush-valve seal or from chain interference. If the fill valve itself never shuts off and water continues toward the overflow tube, focus on the fill-valve setting and operation.
WHEN TO STOP
- If adjusting the float does not stop water entering the overflow path, the fill valve or another part of the refill system may be sticking, contaminated, misconfigured, or failing and should be evaluated.
- If the fill valve is old and corroded, replacement is easier than rebuilding.
WHEN TO CALL A PROFESSIONAL
- You've adjusted the fill valve and water still runs into the overflow tube.
- The fill valve is making noise or not shutting off.
- You're not comfortable replacing the fill valve yourself.