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

Is your cistern leaking? Is the flush button not springing back? Or maybe the cistern isn’t filling with water? Cistern faults and failures happen from time to time, and the older the mechanism, the more often they crop up. Where should you start your check to identify the problem? How can you fix it yourself? See how to sort this out effectively!

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

The first element to check is the float — more specifically, its position. This part links to the valve that lets water in. When the float reaches the right level and moves into the position that closes the valve, water can no longer flow into the cistern. It’s a simple regulating mechanism, but it plays up when the float is set 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 discharged through the overflow, of course, but that constant sound of running water isn’t what you want to hear in your bathroom. How do you adjust the float?

Turn off the water supply valve to the cistern, located on the hose or supply pipe. Remove the cistern lid and set the float to the correct level. Gently bend the arm down a little or tighten the adjustment screw for the float position so the water level isn’t too high and doesn’t cause an overflow.

2. Clean the cistern diaphragm

Another reason the flushing mechanism can go out of adjustment is a dirty diaphragm. When the diaphragm gets heavily soiled, it won’t allow the cistern to shut fully.

The diaphragm sits inside the inlet (fill) valve. When it’s dirty, water keeps seeping into the cistern. It’s a different cause than 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 resolve the issue, you’ll need to replace the entire valve, as the diaphragm may have been permanently damaged.

3. Cistern problems – replacing the seal

The flush valve is the other mechanism responsible for the cistern working properly. It’s installed so that, in its resting position, it blocks water from flowing into the toilet. When you press the flush button, the valve opens and water runs from the cistern into the bowl.

A common fault in this mechanism is damage to the seal, which prevents water from flowing from the cistern into the bowl. When it’s torn, water trickles continuously in a thin, slow stream even when you’re not pressing the button. So how do you replace a damaged flush-valve seal?

Shut off the water, then remove the cistern lid and empty the tank. Mop up any remaining water with a sponge, paper towels or an absorbent cloth. You’ll find the seal just above the outlet. Check its condition. Sometimes the seal flips or becomes misshapen, for example due to dirt. Clean the seal thoroughly and put it back in place. If you’ve done all this and water is still leaking, then the seal needs to be replaced completely.

4. Replacing the entire mechanism

You can take care of all the above causes of cistern failures 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 to buy the exact same model of mechanism you’ve been using so far. That way you can be sure it will fit the cistern and all its components without any hassle.

Each kit comes with installation instructions. No experience or skills in this area? Don’t hesitate to call a professional plumber. Prefer fixing things yourself? This article will certainly help you sort out problems related to a malfunctioning toilet cistern!