How to Replace a Hissing or Overflowing Toilet Fill Valve
Time required: 20-30 mins · Difficulty 1/5
A stuck-open fill valve can overflow the tank and run water onto the floor for hours unnoticed — if you're often away from home, consider a valve with a built-in shutoff or a water leak sensor near the toilet.
Est. DIY Parts: $10 - $16 · Pro Service: $140 - $220 · Est. Savings: $125 - $210
* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.
Parts & Tools You'll Need
- Universal Adjustable Toilet Fill Valve
- Adjustable Wrench
- Sponge or Towel
Step-by-Step Manual
- Turn off the water and drain the tank Shut off the supply valve behind the toilet, flush to empty most of the water, and sponge out what remains in the tank.
- Disconnect the supply line Unscrew the water supply line from the bottom of the old fill valve, placing a towel underneath to catch drips.
- Remove the old fill valve Unscrew the locknut holding the fill valve to the bottom of the tank from underneath, then lift the old valve out through the top of the tank.
- Set the height and install the new valve Adjust the new fill valve to the correct height per its instructions (critical line marked on the shaft should sit above the overflow tube), then place it through the tank hole and hand-tighten the locknut underneath.
- Reconnect the fill tube and supply line Clip the small fill tube onto the overflow tube (angled downward, hooked over the top so it doesn't siphon), then reconnect the water supply line to the valve's shank.
- Turn water back on and adjust Slowly open the supply valve, let the tank fill, and adjust the fill valve's water-level screw or clip so the water shuts off about 1 inch below the overflow tube.