How to repair a toilet cistern – a guide. Check it out!

Is the cistern letting water through? Is the flush button not springing back? Or perhaps the cistern isn’t filling with water? Cistern faults and failures occur from time to time—more often as the mechanism gets older. Where should you start your inspection to identify the problem? How can you fix it yourself? Find out how to solve this problem effectively!

1. How to fix a cistern – start with the float!

The first component to check is the float—more specifically, its position. This part is connected to the inlet valve, whose role is to supply water. When the float reaches the correct level, i.e. moves to the position that closes the valve, water can no longer flow into the cistern. It’s a simple regulating mechanism, but it goes wrong when the float sits too high.

If the float is too high, it won’t shut off the water in the cistern, so water keeps flowing in. It is, of course, diverted via the overflow, but the constant sound of running water isn’t something you want in your bathroom. How do you adjust the float?

Turn off the water supply valve to the cistern, which is on the hose or supply pipe. Remove the cistern lid and adjust the float to the correct level. Gently bend the arm down or tighten the adjustment screw for the float so that the water level isn’t too high and doesn’t cause overflow.

2. Remove dirt from the cistern diaphragm

Another cause of a misadjusted flushing mechanism is a dirty diaphragm. When the diaphragm becomes heavily soiled, it prevents the cistern from closing fully.

The diaphragm sits inside the inlet valve. When the diaphragm is dirty, water constantly seeps into the cistern. It happens differently than with a misadjusted float, but the effect is exactly the same—a leaking cistern.

The best solution is to clean the diaphragm. If cleaning doesn’t fix the problem, you’ll need to invest in a completely new valve, as the diaphragm may have suffered permanent damage.

3. Cistern problems – replacing the seal

The flush valve is the second mechanism responsible for the proper operation of the cistern. It’s fitted so that its position blocks water from flowing into the toilet. When you press the flush button, the valve is released and water runs from the cistern into the bowl.

A common fault with this mechanism is damage to the seal, whose job is to stop water from flowing from the cistern to the bowl. If it is torn, water will trickle continuously in a thin, slow stream even when you don’t press the flush. So how do you replace a damaged flush valve seal?

Turn off the water, then remove the cistern lid and empty the tank. Remove any remaining water with a sponge, paper towels or an absorbent cloth. You’ll find the seal just above the pipe outlet. Check its condition. Sometimes the seal flips over or deforms in other ways, for example due to dirt. Clean the seal thoroughly and refit it. If you’ve done all this and water is still leaking, the seal will need to be replaced completely.

4. Replacing the entire mechanism

You can eliminate all of the cistern faults described above yourself, provided that cleaning the diaphragm or replacing the seal brings tangible results. If adjusting the float, cleaning or replacing the seal, and cleaning the diaphragm don’t help, you may need to replace the entire flushing mechanism.

Want to replace the mechanism yourself? You’ll need the right tools and you should buy exactly the same model of mechanism as the one you’ve been using so far. That way you can be sure it will fit the cistern and all its components without any issues.

Every kit comes with installation instructions. Don’t have experience or the necessary skills? Don’t hesitate to seek professional help from a qualified plumber. Prefer to tackle faults yourself? This article will certainly help you solve problems caused by a malfunctioning toilet cistern!