Toilet Keeps Running? How to Stop It
Modern Perspective Plumbing, licensed plumbing contractor in Grover Beach, serving San Luis Obispo County
Turn off the small valve behind the toilet to stop the water. The usual cause is a worn flapper or a fill valve set too high. Put a few drops of food coloring in the tank and wait about 15 minutes. Color in the bowl means the flapper is leaking.
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What to do first
- Turn the stop valve behind the toilet clockwise to shut off the water.
- Lift the tank lid and check whether water is spilling into the overflow tube.
- Do the dye test: add food coloring to the tank, wait about 15 minutes without flushing and check the bowl.
Call right away if
- Water is on the floor around the toilet
- The stop valve won't turn or it leaks
- Several toilets start running around the same time, which can point to high water pressure
We answer Monday–Friday 8AM–5PM. After hours, we take your details and call back first thing the next business morning, or Monday morning on weekends. No crew goes out overnight.
What usually causes it
- Worn flapper. The rubber seal at the bottom of the tank stops sealing and water slips into the bowl.
- Fill valve. A worn or misadjusted valve keeps filling, and water runs into the overflow tube.
- High water pressure. Pressure over about 80 psi can make toilets run or refill on their own.
Coming out to look is free, and you get the price before any work starts. Learn more about our toilet and fixture repair.
Common questions
Can a running toilet raise my water bill?
Yes. It's one of the most common hidden causes of a higher bill, so check toilets first.
Why does my toilet refill by itself every so often?
Water is usually slipping slowly from the tank into the bowl, often past the flapper. The dye test can confirm it.