Types of taps and the parts that fail most often

Before you buy any spare part, the real first step is knowing exactly what is under the handle. Taps are not all the same inside, even when they look similar outside — the sealing mechanism differs fundamentally between models, and a part that fits one type simply won't go into another. A rubber washer bought at random, without knowing what mechanism you have, is the most common reason people buy the wrong part two or three times before fixing a simple drip.

The difference is financial too: some parts cost very little, others ten times more, and identifying the right one from the start saves time, money and repeat trips to the shop.

The traditional model, with separate handles for cold and hot water, uses simple rubber washers — discs seated on the tap seat that wear down through friction every time you open and close the water. It is the simplest construction of all and, luckily, the cheapest to repair: a new washer costs little and replacing it needs no special tools.

The typical sign of a worn washer on this kind of tap is a drip that starts gradually — occasional at first, then constant — as the rubber wears and no longer seals perfectly on the seat. Because the mechanism is simple, it is also the easiest tap to repair for someone without previous experience.

Modern taps with one handle controlling both flow and temperature by turning and lifting don't use simple washers but an internal ceramic cartridge. That is the part that actually mixes cold and hot water depending on the handle position, using two very smooth ceramic discs sliding over each other. It is more durable than a classic washer — ceramic discs resist wear much better — but a new cartridge costs considerably more than a washer.

When a cartridge fails the signs are usually different from a slow drip: the handle can become stiff, the water can come out at the wrong temperature whatever the handle position, or a drip appears suddenly rather than gradually. For this type, identifying the brand and model correctly matters enormously, because most manufacturers use proprietary, non-standard cartridges.

Rarer in ordinary homes but found in some older models or industrial-style installations, ball-valve taps use a completely different mechanism: a metal ball with openings that rotates inside the tap body to set the mix of hot and cold water. This type has its own sealing parts — small springs, dedicated rubber seals and O-rings — that don't overlap with the parts used in the other two types.

If you come across this type, usually in an older house or one inherited from a previous renovation, the surest guide to the parts is the brand and model marked on the tap body, or on the original packaging if it was kept.

The surest way to know exactly what you have, before buying any part, is to remove the handle and look at the mechanism underneath. On most taps the handle comes off after undoing a screw hidden under a decorative cap, which usually pops off with light pressure or unscrews with a fine screwdriver. Once you see the mechanism — a simple washer on a metal seat, a cylindrical cartridge or a ball mechanism — the difference between types is obvious.

If you'd rather not dismantle anything before buying the part, check the brand and model of the tap, usually on a small label under the handle or on the body, and look up the matching part at a specialist shop or from the manufacturer. Avoid buying 'something similar' without checking — a part with slightly different dimensions won't seal properly, even if it physically fits.