A dripping tap wastes surprisingly large amounts of water, with even a slow drip losing over 5,000 litres a year, and in hard water areas like South West London it often leaves stubborn limescale stains too. The good news is that most drips come down to one worn part that costs a few pounds. Here is how to diagnose and fix it yourself, and how to know when it is worth calling someone in.
Before you buy any parts, identify the tap. Traditional taps that turn several full rotations to open use rubber washers, and these are common in older Victorian and Edwardian terraces across areas like Tooting, Balham and Wandsworth. Modern taps and mixers that only turn a quarter or half turn use ceramic disc cartridges instead, and monobloc kitchen mixers with a single lever use a larger single cartridge.
The distinction matters because the fix is different. A washer tap drips because the rubber washer has hardened or split. A ceramic tap drips because grit or limescale has scored the discs, and in that case you usually replace the whole cartridge rather than a washer. London's hard water is tough on both, so limescale is often part of the problem either way.
Start by isolating the water. Look under the sink for an isolation valve on the pipe feeding the tap and turn the screw slot a quarter turn with a flathead screwdriver. If there is no valve, turn off the main stopcock, usually under the kitchen sink, then open the tap to drain the last of the water. Put the plug in the plughole so small screws cannot disappear down the waste.
Prise off the decorative cap on top of the tap, undo the screw beneath it and lift off the head. Use an adjustable spanner to undo the headgear nut, holding the tap body steady so you do not twist the pipework below. At the bottom of the headgear you will find the washer, either pushed onto a small button or held by a nut. Replace it with a matching one, typically half inch for basin taps and three quarter inch for bath taps, then reassemble and restore the water. A pack of assorted washers costs around 3 to 5 pounds from any DIY shop.
The process starts the same way: isolate the water, remove the cap and screw, and lift off the handle. Undo the retaining nut and pull out the cartridge. Take the old cartridge with you when buying a replacement, because sizes and spline counts vary between manufacturers and a near match will not seal. Cartridges usually cost between 10 and 25 pounds, though some designer brands charge considerably more.
Note that cartridges are handed, so a hot side cartridge will not work on the cold side. If the tap is only a few years old, it is worth contacting the manufacturer first, as many will send a replacement cartridge free under warranty. While the tap is apart, soak any limescale off the seating area with white vinegar, as scale left behind will chew through the new cartridge quickly.
Some jobs are not worth the struggle. If the headgear nut is seized solid, forcing it can crack the ceramic basin or twist the copper pipework, which turns a five pound repair into a much bigger one. Corroded monobloc mixers, taps with no isolation valves, and drips coming from the base of the tap rather than the spout are all sensible reasons to bring someone in.
In London, expect a plumber or maintenance firm to charge roughly 60 to 120 pounds to repair or rewasher a tap, depending on access and parts, and more if the tap needs replacing entirely. Supplying and fitting a new mixer tap typically runs from around 130 to 250 pounds including a mid range tap. Costs depend on the tap, the condition of the pipework and how easy the shut off is, so ask for a clear price before work starts. If you are getting other small jobs done at the same time, such as a running toilet or a slow draining sink, bundling them into one visit is usually better value.
The brass seat the washer presses against is probably worn or scored, often by limescale. It can be reground with an inexpensive reseating tool, or a plumber can do it in minutes; if the tap body itself is corroded, replacement is usually the better option.
Only if there is no isolation valve on the pipe under the sink or basin. Many London homes, especially older ones, lack these valves, and it is worth having them fitted during any repair so future jobs do not mean shutting off the whole house.
A tap dripping once per second wastes roughly 5,000 to 6,000 litres a year. On a water meter that adds a noticeable amount to your bill, and a hot tap drip also wastes the energy used to heat that water.
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