How to Replace a Toilet Fill Valve
Remove a worn or running toilet fill valve, adjust and install a universal replacement unit, and secure all water supply connections without leaking.
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🧰 Required Tools & Equipment
- ✓ Adjustable wrench
- ✓ Slip-joint pliers
- ✓ Small bucket or catch pan
- ✓ Car wash sponge or large towel
📦 Materials & Supplies
- ✓ Universal toilet fill valve kit
- ✓ Refill tube and angle adapter clip
⚠️ Safety Checkpoints & Warnings
- • Verify the water supply shut-off valve is completely closed before disconnecting any plumbing lines.
- • Do not overtighten plastic nuts against porcelain; excessive torque will crack the ceramic tank.
- • Wipe up spilled water immediately to prevent slips on hard bathroom flooring.
📋 Step-by-Step Guide (6 Steps)
Shut Off Water Supply and Drain Tank
Locate the oval shut-off valve on the wall beneath the toilet and turn it fully clockwise until it stops. Flush the toilet and hold down the trip lever to discharge maximum water from the tank. Use a sponge to soak up the remaining 1-2 inches of standing water at the bottom, wringing it out into a bucket until the tank floor is completely dry.
- • Shut-off valve handle turned completely clockwise.
- • Toilet tank completely empty of standing water.
- • Forgetting to sponge out the remaining water, causing a flood when the old valve is unbolted.
Disconnect Water Line and Remove Old Valve
Place a catch bucket directly under the water inlet shank beneath the toilet tank. Use an adjustable wrench to loosen the water supply coupling nut counter-clockwise, then unscrew it by hand. Unscrew the large plastic mounting locknut securing the fill valve shank to the bottom exterior of the tank, then lift the entire old fill valve straight up and out of the tank.
- • Flexible supply line free and resting in the catch bucket.
- • Old fill valve fully removed from the tank, exposing an open mounting hole.
- • Unscrewing the tank-to-bowl bolts instead of the center fill valve mounting nut.
Adjust New Fill Valve Height
Hold the new fill valve next to the overflow tube inside the tank. Twist the threaded lower shank counter-clockwise to unlock and extend the body until the 'Critical Level' (C.L.) mark molded on the valve body sits at least 1 inch above the top rim of the overflow pipe. Twist the shank back clockwise to lock the height adjustment securely into place.
- • Critical Level line on the new valve visible 1 to 3 inches higher than the overflow pipe top edge.
- • Shank locking ring firmly engaged in its detent.
- • Setting the valve too high, preventing the toilet tank lid from seating flat.
Install and Fasten the New Valve
Slide the rubber shank washer onto the bottom of the new valve with the tapered/beveled side facing downward toward the tank floor. Insert the threaded shank through the hole in the bottom of the tank. Thread the plastic locknut onto the shank from underneath the tank, tightening firmly by hand, then use slip-joint pliers to give it no more than an additional 1/4 to 1/2 turn.
- • Rubber washer fully compressed flat against inside bottom of tank.
- • Locknut flush against porcelain underside with no wobble in the valve body.
- • Overtightening the plastic locknut with pliers, which distorts the rubber seal or cracks the tank.
Connect the Refill Tube
Push one end of the black rubber refill tube firmly onto the nipple near the top of the new fill valve. Attach the plastic angle clip to the opposite end of the tube and snap the clip onto the rim of the overflow pipe, directing water flow downward into the tube. Trim the hose with scissors if it has excess slack or kinks.
- • Refill tube securely attached to valve nipple and clipped to overflow pipe.
- • Hose forms a smooth, unkinked arch above the water line without sagging below the overflow pipe rim.
- • Shoving the refill hose straight down inside the overflow pipe without a clip, which creates a permanent siphon draining the tank.
Reconnect Supply Line and Test for Leaks
Thread the water supply line coupling nut back onto the bottom of the fill valve shank by hand, then snug it 1/4 turn with an adjustable wrench. Slowly turn the wall shut-off valve counter-clockwise to restore water flow while watching the bottom connections closely. Let the tank fill completely and verify that the valve automatically shuts off when water reaches the marked fill line (about 1/2 to 1 inch below the top of the overflow pipe).
- • Tank fills smoothly and water shuts off completely at the indicated water line.
- • No water drips appearing around the bottom locknut or supply connection after 2 minutes.
- • Cross-threading the plastic threads on the bottom of the fill valve shank with the metal supply line nut.
Credit: inspired by an original tutorial by The Home Depot — watch the original on YouTube.
Don’t have everything?
- No Car wash sponge? Old bath towel or turkey baster to remove standing water
- No Slip-joint pliers? Channel-lock pliers or hand-tightening only for plastic nuts