How to Replace a Toilet Fill Valve

Turn off water, drain the tank, disconnect the old fill valve, and install the new one by connecting the chain and adjusting the water level.

1. Shut Off Water First. Locate the shut-off valve behind the toilet near the floor and turn it clockwise until it stops. This valve controls water flow to your toilet tank.
2. Drain the Tank Completely. Flush the toilet to drain most of the water from the tank. Use a sponge or towel to soak up any remaining water in the bottom of the tank.
3. Remove Supply Connection. Unscrew the supply line connection at the bottom of the fill valve using adjustable pliers. Have a bucket ready to catch any water that spills out.
4. Extract Old Valve. Unscrew the plastic nut holding the fill valve to the tank from underneath the toilet tank. The entire fill valve assembly should lift out of the tank.
5. Set New Valve in Place. Insert the new fill valve through the hole in the tank bottom. Thread the plastic nut onto the valve from underneath and hand-tighten, then snug with pliers. Do not overtighten.
6. Reattach Supply Line. Attach the water supply line to the new fill valve and tighten with pliers. Make sure the connection is snug but not overly tight to avoid cracking the plastic.
7. Set Chain Tension Right. Attach the chain from the flush handle to the flapper. The chain should have slight slack when the flapper is closed but not so much that it gets caught under the flapper.
8. Fine-Tune Water Level. Turn the shut-off valve counterclockwise to restore water flow. Let the tank fill and adjust the water level by bending the float arm or adjusting the screw on top of the fill valve until water stops at the marked line.