Running toilet — flush debris out of the fill valve

If the flapper seals but the tank keeps filling or hissing, grit may be holding the fill valve open. After plumbing work or a water shutoff, it is a common cause.

Flush grit out of the toilet fill valve

1. Turn off the water at the supply valve and flush to empty the tank.
2. Remove the top of the fill valve using your model’s instructions. Many twist off, but they differ.
3. Hold a cup over the valve, turn the water on briefly, then off again. Grit blows into the cup.
4. Replace the cap, turn the water back on and watch the fill stop.

If the valve still will not shut off, replace the fill valve rather than fight it. If water is spilling over the top of the overflow pipe, start with toilet water spilling into the overflow tube.

More help

• Same niche: Check toilet fill valve float height · Toilet ghost flushes or refills on its own · Toilet still runs after a new flapper · Toilet water spilling into the overflow tube · Running toilet — check the supply valve for drips after a fix · All running toilet guides
• Related fixes elsewhere: Refrigerator water filter — slow dispenser? check the water line