How to Replace a Toilet Fill Valve and Flapper

The first step is to prepare your workspace and shut off the water to the toilet. Locate the water supply shut-off valve, typically on the wall or floor behind the toilet, and turn it clockwise until it stops. Next, flush the toilet to empty as much water as possible from the tank. There will be about an inch of water left at the bottom; use a large sponge or an old towel to soak up this remaining water and wring it into a bucket. A dry tank prevents messes and makes the next steps easier.

With the tank empty, you can now remove the old parts. First, unhook the old flapper. Gently unclip its two 'ears' from the pegs on the sides of the flush valve overflow pipe. Then, unclip the chain from the flush lever arm inside the tank. The flapper can now be lifted out. Next, address the fill valve. Place your bucket under the toilet tank to catch any trapped water. Use an adjustable wrench or channel-lock pliers to loosen the coupling nut connecting the water supply line to the bottom of the fill valve shank. Unscrew it the rest of the way by hand. Finally, unscrew the large plastic locknut that holds the fill valve to the tank. Once the locknut is removed, you can lift the old fill valve straight up and out of the tank.

Before installing the new parts, wipe the area around the fill valve hole inside the tank and the flush valve seat where the flapper sits to ensure a clean, smooth surface for a good seal. Now, install the new flapper. Align the two holes or 'ears' on the new flapper with the corresponding pegs on the overflow pipe and press them on securely. Next, attach the clip on the end of the new flapper's chain to one of the holes on the toilet's flush lever arm. Leave a little bit of slack in the chain—about 1/2 inch is ideal. Too much slack and the flapper won't lift; too little and it won't seal properly.

Now, install the new fill valve. First, adjust the height of the new fill valve according to the manufacturer's instructions; typically, you twist the shaft to extend or shorten it. The top of the fill valve should sit about 3 inches above the top of the overflow pipe. Insert the threaded shank of the new fill valve through the hole in the bottom of the tank. Make sure the included rubber gasket is seated properly on the inside of the tank. From underneath the tank, thread the plastic locknut onto the fill valve shank. Hand-tighten the locknut until it is snug. Then, use your wrench to give it an additional quarter to half turn. Do not over-tighten.

With the new parts installed, it's time to reconnect everything. First, attach the small rubber refill tube to the nipple on the side of the new fill valve. Clip the other end of the tube to the top of the overflow pipe using the provided angle adapter; this ensures water from the fill valve refills the toilet bowl after a flush. Next, re-attach the water supply line. Screw the coupling nut onto the threaded shank of the new fill valve by hand until it's snug. Use your adjustable wrench to give it a gentle final turn (about a quarter turn). Now, you can turn the water back on. Slowly turn the shut-off valve counter-clockwise. As the tank fills, carefully inspect the connections at the bottom of the tank for any drips or leaks.

The final step is to adjust the water level and test the flush. Let the tank fill completely. The water should stop filling when the level is about 1/2 to 1 inch below the top of the overflow pipe. If the water is too high or too low, adjust the float on the fill valve. For float-cup style valves, this is usually done by turning an adjustment screw or squeezing a spring clip and sliding the float up or down the fill valve shaft. Refer to your specific model's instructions. Once the water level is set, flush the toilet. Watch to ensure the flapper lifts correctly, stays up long enough for a full flush, and then seals completely. Check that the chain doesn't get tangled or caught. Flush a few more times to confirm everything is working smoothly and there are no leaks.