How to Isolate Your Toilet Cistern Water Supply

Whether you're replacing your inlet valve or servicing your inlet diaphragm washer, the first crucial step is to isolate the water supply to your cistern.

There are a number of ways to isolate the water supply and there are numerous different types of isolation valve; every toilet setup is different. Below are some tips on where your isolation valve may be, what types of isolation valve there are, and how to isolate the water supply.

The most common location for toilet cistern isolation valves is underneath the cistern itself. This can either be an independent isolation valve on the pipework with a female to female flexible tap connector attached to it, or a flexible tap connector with an integrated isolation valve.

This isolation valve is usually a traditional screwed isolation valve. This type of valve will have a flat-head screw that needs to be turned 90 degrees in order to isolate the water. For this type of valve you'll need regular flat head screwdriver. Sometimes there can be a lever isolation valve which requires no tools in order to isolate, just turn the lever 90 degrees.

If there is no isolation valve underneath the toilet cistern, then it may be elsewhere in the bathroom or in another room such as the kitchen if it is below the bathroom. Sometimes if there is no isolation valve in the bathroom then there may be two isolation valves in another room, one for the cold water supply and one for the hot water supply. These valves will usually isolate the complete bathroom, not just the toilet cistern.

If the valves are elsewhere then they may be one of four different types of isolation valve, a screwed isolation valve, a lever isolation valve, a traditional stopcock or a Surestop.

A traditional stopcock can be easily identified from it's old fashioned tap head style control. Simply turn this valve clockwise in order to isolate the water supply. A Surestop is one of the most convenient types of isolation valve, this will be a simple switch on the wall or inside of a cabinet with the Surestop logo on it. Simply press the switch and the water supply should be isolated.

If none of these valves are available then the complete water system may need to be switched off at the main stopcock or as an absolute last resort switched off via the external stopcock.

As always with these types of jobs, we always recommend contacting a professional if you're in any doubt.