The majority of kitchen sinks, bath tubs and bathroom basins are fitted with individual taps for hot and cold water. Wall-mounted taps are known as bib tabs, but those mounted directly onto the sink, basin or tub are called pillar taps. There are also mixer taps, which have a hot and cold valve linked to a common spout. Water regulations require that mains water and stored water cannot be mixed in a system, so a sink mixer has separate waterways to isolate mains-supplied cold drinking water from storage cylinder-supplied hot water.

Tap Design

In recent years there have been many changes to tap design, both in their appearance and in the mechanics of the tap itself. A traditional pillar tap comprises a capstan head - the cross-shaped handle - a metal shroud, which covers the gland nut, a spindle and headgear nut. This was attached to a jumper with a washer, which fitted into the tap body, which in turn fitted to the supply pipe. When you turn on this type of tap, the entire spindle, jumper and washer move up and down and turn along with the capstan head.

Now there are taps with non-rising heads: while outwardly they look like old spindle taps, inside, when they are turned on, a threaded spindle and washer unit rises up and down without turning. These have the advantage over old spindle taps because the washer is not twisted against the seat of the tap so it doesn't wear out as quickly. In other taps, the traditional rubber washer has been replaced with precision ground ceramic discs, which rotate on each other with little wear - and no build up of limescale deposits.

Reverse-pressure taps are a sort of upside-down version of standard taps. Here the head and spout hang from the water inlet and a check valve automatically shuts off the water if a washer needs to be changed. Where hygiene is of great concern - in hospitals, for example - electronic taps operated by photocells, which sense the presence of someone's hands, allow water to flow from the taps automatically.

Tap Problems

A leaking tap is a common plumbing problem. Not only is the constant drip irritating but it is also a waste of a very valuable resource. And if the drip is from a hot tap, then you're wasting

both the water and the fuel needed to heat it. The weak point in rising spindle taps and non-rising head taps remains the washer. When water is dripping from the spout, it's a sign of a worn washer. Washers for cold taps used to be made of leather, then black rubber, and hot tap washers first from a red fibre or rubber-asbestos before nylon ones were introduced. Hot and cold washers are still made, but it's a lot easier to buy a 'universal' washer as this can be used on either tap - but make sure you buy the right diameter.

If water leaks from the top of the tap head when you turn it on, then it's the gland packing or '0' ring (on a mixer tap) that needs to be replaced. Both are very simple DIY repairs. Put the plug in the sink and then lay a towel in it - if a tap or tiny nut drops in, it won't get damaged or lost down the wastepipe.

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