Most cisterns, including My Ideal Cistern, use a ball valve to moderate the amount of water that is allowed into the tank of the cistern when the handle is flushed. The ball valve can wear out over time or become corroded from the exposure to water and air continuously, causing the valve to seize up and stop working efficiently. Replacing the ball valve of the cistern is not difficult and can be completed in about 30 minutes with basic tools.
Turn off the water supply to the cistern at the shut-off valve behind the fixture. Remove the nut that fastens the supply pipe to the ball valve with an open-end wrench.
Loosen the two nuts on both the inside and outside of the cistern that fastens the ball valve to the fixture with an open-end wrench. Take the ball valve off of the cistern.
Tighten a nut down all the way on the threads of the new ball valve. Position the new valve inside the cistern with the threads sticking through the hole in the fixture.
Place the other nut over the threads of the ball valve on the outside of the cistern. Tighten the nut with the open-end wrench so that the ball valve is secure.
Put a washer over the threads on the ball valve. Attach the supply pipe to the ball valve by tightening the nut on the supply pipe with the open-end wrench.
Turn the water back on to the cistern at the shut-off valve behind the fixture.
Always turn off the water supply to the cistern before attempting to replace the ball valve.