How to Replace a Toilet Fill Valve

T-h-e silent hiss of a running toilet is a telltale sign of a failing fill valve, costing you gallons of wasted water every single day. Most homeowners ignore this sound until their water bill spikes, but the mechanical reality is simple: the internal gasket has worn down or the float has lost its buoyancy. Replacing this component is a rite of passage for any homeowner. You don't need a plumber for this, just a steady hand and a clear workspace. When done correctly, your toilet will refill quietly and shut off reliably, ending that persistent trickling sound once and for all.

1. Shut Off the Water First. Locate the shut-off valve behind the toilet and turn it clockwise until it stops. Flush the toilet to drain as much water as possible from the tank.
2. Disconnect the Supply Line. Place a small bucket or towel under the tank connection. Use adjustable pliers to unscrew the nut connecting the water supply line to the fill valve shank beneath the tank.
3. Lift Out the Old Valve. Unscrew the plastic mounting nut from the fill valve shank underneath the tank. Pull the old fill valve straight up and out of the tank.
4. Set the Valve Height. Measure your old valve and adjust the height of the new fill valve by twisting the shank. The top of the overflow pipe should be about an inch lower than the fill valve cap.
5. Secure the New Valve. Insert the new fill valve through the hole in the bottom of the tank, ensuring the rubber gasket is seated flat inside. Secure it from underneath with the included mounting nut, tightening it firmly by hand plus a quarter turn with pliers.
6. Test and Adjust. Attach the water supply line to the shank, then turn the water back on slowly. Check for leaks at the connection point and adjust the float level if the water line doesn't sit an inch below the overflow pipe.