How to Repair Noisy Toilet Cisterns

The inside of a toilet cistern.

Noisy toilet cisterns are a common problem in most households. They can be especially annoying if the toilet is situated close to a bedroom. The main reason behind this problem is that cisterns are usually the most overworked parts in a plumbing system.

However, a noisy toilet cistern can easily be repaired with basic plumbing tools and in a very short time. There can be many reasons behind a noisy toilet cistern. Listed below are some of the most common problems and the ways to fix them.

Dirty Valve

One of the most common reasons behind a noisy cistern is dirt and debris getting stuck in the fill valve. A horn or whistle-like sound is caused due to water pressure running across this dirt and debris. Fixing this problem is quite easy. The first thing you have to do is turn off the water supply, then open the top of this valve and check for debris or dirt. If you find any dirt, remove it and restore the top of the valve. Turn the water supply on and check the pipe for any leaks. This should stop the noise from the cistern.

Water Hammer

Another common problem is a humming noise when the toilet is flushed. This can be caused due to a worn valve diaphragm washer, which is a relatively easy repair. All you have to do is replace the washer. Always remember to turn off the water supply first. Go in, split the ball valve and you will find a black rubber washer. Replace this with a new washer. Place it in correctly and put the ball valve back.

Broken Float Switch

If the water in the cistern is overflowing from the pipe in the center, the problem could be a broken float switch. It can also be caused if the float switch is not adjusted properly. There are two ways to adjust this switch. One way is by unscrewing the float a bit using the adjustment screw on top of the valve to regulate the float. If the float switch is broken, you may have to change it completely.

Vibration in Washer Assembly and Stem

If you find your toilet cistern making a loud noise like a horn when flushing, the problem can be due to vibration of the fill valve’s washer assembly and stem. To solve this problem, turn off the water supply again. Unscrew the top of the fill valve or ballcock assembly, which is inside the cistern.

Take out the washer assembly, stem, and float ball; then pry out the washer and turn it over. Firmly press it back into place, and with your hand over the open ballcock, turn on the water. This will flush out any crud that could be stuck inside. Once you have done this, reassemble the system and test flush it.