A dripping tap is one of those faults that starts as a minor annoyance and quietly turns into wasted water, stained ceramics and higher bills. The good news is that the cause is nearly always one of a handful of worn parts, and most are quick to put right. Here is what is actually going on inside your tap, and what to do about it.
Traditional taps with separate hot and cold handles seal with a small rubber washer that gets compressed against a brass seat every time you turn the tap off. After years of use the rubber hardens, splits or wears thin, and water sneaks past even when the tap feels fully closed. This is the single most common cause we see in older London homes, particularly in pre-1980s bathrooms that still have their original taps.
Modern mixer and monobloc taps work differently. They use a ceramic disc cartridge instead of a washer, and when the discs wear or grit gets between them, the tap drips or the handle feels loose and scratchy. Cartridges do not fail as often as washers, but when they do, the whole cartridge needs replacing rather than a single rubber part. A drip from around the base of the spout or handle, rather than the nozzle, usually points to a perished O-ring instead.
South West London sits on some of the hardest water in the country, typically around 250 to 300 mg per litre of calcium carbonate. That limescale builds up on washers, seats and ceramic discs, stopping them sealing cleanly and roughening the surfaces so they wear faster. It is why taps in Wandsworth, Kingston or Richmond often need attention sooner than the same tap would in a soft water area.
High mains pressure plays a part too. Some streets have incoming pressure well above the 1 to 3 bar most tap components are designed around, which hammers the washer against its seat and shortens its life. If several taps in your home have started dripping within a year or two of each other, pressure or scale is often the underlying reason rather than bad luck.
Replacing a washer is a realistic DIY job if you are comfortable with basic tools. Turn off the isolation valve under the sink or the main stopcock, open the tap to drain it, remove the handle and headgear, and swap the washer for a matching size, usually half inch for basin taps and three quarter inch for bath taps. Washers cost pennies and the job takes twenty minutes if nothing is seized.
Where it gets harder is when the headgear is scaled solid, the valve seat is pitted, or you have a mixer tap needing a specific cartridge that has to be identified and ordered. Forcing a seized tap can crack the ceramic basin or shear the tap body, turning a small job into a replacement. If the tap will not budge with reasonable effort, stop and get a plumber in rather than leaning on it.
A plumber will isolate the supply, strip the tap, identify the worn part and either replace it or advise you if the tap is beyond economic repair. In London, a straightforward washer or O-ring change typically falls in the region of 80 to 150 pounds including parts, while a cartridge replacement is usually 100 to 180 pounds depending on the make, since some designer cartridges cost 40 pounds or more on their own. These are guide figures rather than quotes, as access, tap condition and parts availability all move the price.
Sometimes replacement is the honest recommendation. If a tap is heavily scaled, obsolete or the chrome is failing, fitting a new mid-range tap at 60 to 150 pounds plus labour often works out better value than repeatedly repairing an old one. A decent plumber should talk you through both options before starting.
A tap dripping once per second wastes in the order of 5,000 litres a year. If you are on a water meter, as most newer London connections are, that is money straight down the drain, and if it is the hot tap dripping you are paying to heat that water too.
Constant drips also leave brown or green staining on baths and basins, encourage limescale build-up around the plughole, and put strain on the rest of the tap. Left long enough, a drip often develops into a steady trickle that no longer responds to tightening the handle. A quick repair now is almost always cheaper than the consequences of ignoring it.
No, and it usually makes things worse. Overtightening crushes the worn washer further and can damage the brass seat, so the drip returns faster and the eventual repair is bigger. If a tap needs force to shut off, a part inside has worn and needs replacing.
As a rule of thumb, taps with separate hot and cold handles that turn several times use washers, while mixer taps and taps that go from off to full flow in a quarter turn use ceramic cartridges. If you are unsure, a plumber can tell within seconds of removing the handle.
Occasionally. If several taps drip or the problem keeps returning soon after repair, high mains pressure or heavy limescale may be the root cause, and fitting a pressure reducing valve or descaling can save repeated call-outs. A drip from under the sink rather than the spout is a leak, not a drip, and needs looking at promptly.
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