How to Install a Toilet Cistern

What You'll Need
Soil pipe
Flush pipe
Steel screws
Ball valve

When installing a new toilet cistern you need to ensure that, apart from the toilet itself, you purchase all the right fittings, including an appropriate connection to fit your waste outlet pipe. The watertight seal is achieved by manifolds of rubber fins, but the basic connection itself is a push fit, making it remarkably easy to fit. When shopping for these push-fit waste outlet connections you will note that they are either straight, offset, radii or angled to cover all eventualities. The choice you make is dependent on your existing waste outlet pipe, the size of the pipe and its position relative to the toilet pan. Before you set out to shop for a new toilet be sure to measure the internal diameter of the soil pipe as well as the external diameter of the pan outlet. Take note of the measurements in terms of distance between the outlet waste pipe and your existing toilet’s soil pipe, as well as the angle required.

Step 1 - Connecting the Outlet Pipes

Before you get around to actually installing the toilet cistern you need to get the pan in place and fit up the connectors. Once you have positioned the toilet pan where you want it, fit the connector inside the soil pipe. Now, to ensure the pan is positioned correctly before fixing it in position, mark the fixing points on the floor. Once these have been marked, move the pan so that you can drill into these fixing points and plug them if necessary. It is always best to make sure there are no cables or other pipes running beneath the fixing sites. Place the pan back in position but before fixing it permanently, you need to assemble the toilet cistern. 

Step 2 -  Fixing the Toilet Cistern

Read any assembly instructions you may have before you begin to assemble the toilet cistern. Different manufacturers have different assembly instructions when it comes to the toilet cistern. Check if you have all the correct mountings so that you can assemble all the internal parts of the toilet cistern. You may have a flush pipe or you may not, depending on whether or not your cistern is mounted directly onto the toilet pan. 

Step 3 - Preparing the Fixing Points

Check that everything is level. This is easily done using a spirit level or one of the newly introduced laser levels. Take your time to get it right but, once you are sure you have everything completely level, make a note of all the fixing points for the toilet cistern. Carefully lift the toilet cistern away from the wall and drill a hole at each fixing point. Now plug each of these holes. Put the toilet cistern back in position and fix it into place. 

Step 4 - Using Non-Corrosive Screws

Avoid using steel screws as these are likely to corrode due to the increased likelihood of moisture in this area. Fix the new toilet cistern to the wall using brass screws preferably. As you are screwing these into place remember to take special care not to over-tighten to prevent damage. 

Step 5 -Finishing Up

Once you have fitted the pan in place, attach the toilet cistern and the cold water feed together. Follow your manufacturer’s assembly instructions to fit the ball valve to the water feed. While you are doing this, it might be an idea to add a miniature stop valve so that you can isolate the toilet cistern in the event of a future leak. Now connect up the overflow pipe to the toilet cistern. The overflow pipe runs out through an external wall and, as it is dependent on gravity and it needs to be set slightly downhill, preferably empties into an external drain.  

The best size for an overflow pipe is 21cm in diameter. Finally, turn the water supply on again and allow the toilet cistern to fill up to around 20mm beneath the overflow outlet. Quite often it is necessary to adjust the ball valve to get it right. Check for any leaks and, if none are found, you have now learned how to install a toilet cistern.