Taps in current use comprise an 'underpart', which includes the nozzle, joined to the water pipe (and usually to the washbasin, sink or bath too, or to the wall behind). The 'movable top section' of which the knob is part contains the washer.

Tap washers tend to wear with use and age, particularly the one fitted above the pipe inlet. This is at the lower end of the removable top section, and is held in place by a small screw.

Loosen this before replacing the washer and finally screw it tight again.

Bear in mind that the 'seating', into which the washer fits on a tap that has been in use for a long time, may have difficult to remove.

This means that you should first try to remove any sediment with a blunt ended instrument such as a flat screwdriver. Work carefully and if this doesn't do the trick, try a plumber's wrench.

Acquaint yourself with the segmented sections of a pillar tap before you need to change the washer. If the tap drips it is usually because the bottom washer is worn.

Follow this step-by-step method for changing the washer:

? Turn off the water supply at the mains or from the supply tank. In most modern premises this is the 'stopcock' ? a tap fitted into the incoming water supply pipe ? either positioned under or alongside the basin, sink or bath.

Note that with combination cold/hot water tap fittings it will be necessary to find two stopcocks and turn them both off. If one or both of these are not traceable, then there must be an individual stopcock serving the cold water supply to your home ? locate and turn off this stopcock.

? Open the tap fully and wait until the water supply stops completely.

Leaks at the tap spindle

Sometimes water oozes out between the tap spindle (E) and the shield and, to put this right, you need to tighten the gland nut. ? Open the tap fully ? in this case there's no need to turn off the water supply.
? Remove the handle (A) and loosen the cover (B).
? Tighten the gland nut (F) about half a turn, using a spanner.
? Replace the handle and check if the tap turns on and off easily. If so, then reassemble the tap. If not, then adjust the gland nut again and reassemble the tap.

'O' rings

In many modern taps, the 'O' ring has replaced the old style packed gland or stuffing box found in traditional shaped taps. Although leaks from this type of tap are rare, you may at some point have to replace the 'O' ring. You can do this by simply undoing the hand-adjusting nut, picking out the old 'O' ring and replacing it with a new one.

'O' rings are also found at the swivel point of most mixer taps. If a leak should occur here, remove the spout, which is held in place with a grub-screw so that you can change the 'O' ring.

Airlocks

If water comes from the taps in fits and starts and then finally stops, or if you turn on the taps and hear a banging, hammering or whining noise, there is most propably an airlock in the system.

This problem can often be cured easily if you have separate hot and cold mains taps in the kitchen. Simply take a short length of hosepipe and two adjustable hose clips and fix the hosepipe between the hot and cold water taps.

Then turn the taps on full so that the mains pressure forces the air in the pipework upwards and out through the bathroom taps (which should be turned on). This will allow the water to finally exit through the expansion pipe above the cold water cistern.

However, if the problem is in the pipe serving a mixer tap in the kitchen or bathroom, remove the spout and press a cloth tightly against the spout hole. It would be advisable to get someone else to turn on the hot water tap and then the cold one ? this should do the trick.

Cisterns

If your toilet cistern overflows, it could be due to the float arm being set too high. On modern cisterns, there is an adjustment for loosening a nut and lowering the ball float by about 2,5cm. With the old type of cistern, the soft metal float arm has to be bent down with a pair of grips or an adjustable spanner.

Do not attempt to bend a plastic arm, as it is likely to break. After you have made the adjustment, check the water level in the cistern and if it still overflows, make a further adjustment until a satisfactory level is obtained and the water levels off below the overflow outlet.

If this doesn't cure the problem, you should look at the ball float itself, which may have corroded, allowing the water to enter. Before dealing with this problem it is necessary to tie up the float arm or turn off the water to the cistern, whichever is easier.

Then unscrew the ball float from the arm and inspect it. Give it a good shake to determine if there is water inside. If there is water inside, replace it with a new one. You can however perform a makeshift repair by tying a plastic bag around the damaged float, after shaking the water out and replacing it in position.

A worn washer in the inlet valve can also cause the cistern to overflow because it allows the valve to drip. Follow this step-by-step guide if you discover a worn washer:

? Turn off the water supply to the cistern.
? Remove the split pin that holds the float arm to the valve and the circular rubber washer.
? Fit the new washer into place.
? Screw on the end cap and return the piston into the housing.
? Refit the float arm and split pin.
? Move the float arm up and down to make sure that it's completely free and not obstructed in any way.
? Turn on the water and check that the cistern is working satisfactorily.