To remove a ballcock valve from a toilet, turn off the water, remove all the water from the tank, disconnect the water supply line, and loosen the nut to lift the assembly from the tank. Install the new valve, and then adjust the float.
- Empty the tank
Locate the supply valve under the tank, and turn the knob counter-clockwise until it stops. Press and hold the flush valve to drain as much water as possible from the tank. Use a sponge to absorb any remaining water.
- Disconnect and remove the valve
Place a bucket under the assembly to catch any remaining water. Disconnect the water supply line from the valve assembly. Remove the retaining nut from the tailpiece of the assembly, and lift the ballcock valve out of the toilet.
- Install the new valve
Place the gasket on the tailpiece, and insert the tailpiece into the hole in the tank. Screw the retaining nut firmly against the tank, but avoid putting too much pressure on the porcelain. Attach the water supply line.
- Adjust the valve
Turn on the water, and allow the tank to fill. Check for leaks. Adjust the ballcock so the water level is just below the top of the overflow tube.