Apart from the kitchen sink, the most used and overworked piece of plumbing kit in the whole house has to be the toilet, particularly if you have kids. The last thing you want if for your toilet to stop working and then have to wait until the next day to get a plumber to repair it.

Problems with a toilet flush

Obviously, constant use of an appliance means increased wear, but regular maintenance checks should keep problems to a minimum. There are basically three types of toilet cistern: low-level (easy to maintain), high-level (accessible by stepladder) or concealed, which may present maintenance access problems if the toilet installation wasn’t well planned. The working components in a toilet’s cistern are readily available for replacement or repair from a plumber’s merchant or a DIY store.

Bathroom Tip: When purchasing a replacement part for you toilet, take the old one with you to make sure you are buying the right type. Also, write down the name and make of the bathroom suite. Or even better, telephone ahead to avoid a wasted journey to the bathroom DIY shop.

How does a toilet flush?

The most common flushing system is operated by a direct-action toilet cistern. Water enters the cistern via the supply pipe and is controlled by a valve. This valve is in turn controlled by a hollow plastic float on an extended arm, which opens or closes the valve as the water level inside the cistern changes. The water level is preset to the required volume necessary for flushing.

The most comman problems

A few problems can occur in a toilet cistern, the most common being a faulty float valve or a poorly adjusted float arm. Evidence of either of these is clearly visible from the outside, when water drips or runs from the overflow pipe. When this occurs your cistern will be constantly filling, which is both noisy and wasteful.

Float valve problems

Float valves are used in two types of situations – loft storage tanks and toilet cisterns. In a conventional system the cold-water storage tank in the loft supplies all the hot and cold water for the bathroom. If the overflow is running from this tank, you will need to shut off the water supply and change the washer in the float valve.

When you have shut off the water supply, turn on all the bathroom taps and flush the toilet repeatedly to empty the tank. Disconnect the valve from its supply pipe and remove it from the cistern. Remove the split pin from the valve 1, releasing the float arm. Unscrew the cap at the end of the float valve 2, remove the piston from the body and unscrew the piston end cap. To prevent the piston from rotating, insert a slotted screwdriver into the gap. Remove the old washer 3 and clean any debris off the cap using wire wool 4. Fit the new washer, lubricating it with a touch of silicone grease 5. Replace the piston, reconnect the float arm to the valve and replace the split pin.

An adjustment screw on the type of float valve used in the toilet cistern controls the water level within the cistern 6. If, after reducing the level the valve still lets water get by, this is normally an indication that either the washer or the diaphragm, depending on valve type, needs replacing.

Changing a toilets Washer

The most common float-valve system today uses a diaphragm valve, replacing the old washer with a large diaphragm that is less susceptible to wear and limescale. The newer valve appears to be much more durable and reduces maintenance.

To change the diaphragm, isolate the water supply and drain the cistern by flushing the toilet. Undo the nut connecting the float arm at the top of the valve and put it to one side. Unscrew the ball-valve assembly, then remove the plastic piston 7. Remove the worn diaphragm, clean off any residue build-up, and fit a new diaphragm 8, adding a touch of silicone grease to act as a lubricant. Reassemble all the bits and turn the water back on.

Replacing a toilets Flap Valve

Having to press the lever repeatedly to get the toilet to flush indicates that the flap valve is probably faulty and requires replacing. To replace the flap valve, first tie the float arm to a wooden batten laid across the cistern, to prevent it refilling. Flush the cistern to clear the water and check the float arm is not allowing the cistern to refill. Unscrew the large nut that connects the flush pipe to the cistern, and move it aside.

Undo the siphon-retaining nut to the toilet cistern base (some water will spill out at this point, so have some towels or cloths ready). Disconnect the flushing arm 9 and carefully ease out the siphon. Remove the diaphragm from the metal plate and replace it with a new one. Reassemble the flushing system, reconnecting the flush pipe to complete the job.