Kitchen Mixer Tap Leaking? How to Fix Each Type of Leak

Updated July 2026 · Emergency Plumber Chelsea

Before you take anything apart, turn the water off to the tap. Under the sink there are usually two small isolation valves on the hot and cold supplies, each with a slot for a flat-head screwdriver. Turn each slot so it sits across the pipe. Open the tap to let the pressure out and check the flow stops. If there are no isolation valves, or they will not turn, turn off the main stopcock; our guide on how to turn off a stopcock shows which way. Put the plug in the sink so small screws and clips cannot drop down the waste.

A spout that keeps dripping when the tap is off is the most common mixer tap leak. Single-lever mixers use one cartridge containing two ceramic discs that slide over each other to control flow and temperature. Twin-handle mixers usually have a ceramic disc cartridge under each handle. London's hard water leaves limescale on the discs, and grit from the mains can score them, so they no longer seal. The fix is a new cartridge. Remove the handle, which is usually held by a small grub screw under a decorative cap, unscrew the shroud or retaining nut, and lift the cartridge out. Take the old one to a plumbers' merchant to match it exactly, because cartridges vary by make, size and spline count and a near match will not seal. If the spout is running rather than dripping and the lever will not shut it off, follow our guide to a tap that won't turn off first.

Water coming out around the base of the spout while the tap is running means the O-rings that seal the swivel spout to the tap body have worn. You will often notice it most when the spout is swung from side to side. With the water off, the spout usually lifts off after loosening a grub screw at the back or a collar at its base. Replace the rubber O-rings with the correct size and smear them with silicone grease before refitting. Do not use ordinary petroleum grease, which can make some rubber seals swell and fail.

Water leaking from under the handle usually means the cartridge's own seals have failed, or the retaining nut holding the cartridge down has worked loose. Tighten the nut gently first. If water still appears around the handle, replace the cartridge. On older twin-handle kitchen taps with rising spindles, the leak may be from the gland packing around the spindle, which can be tightened a quarter turn or repacked.

Water on the worktop around the base of the tap, or a tap body that moves when you use it, means the base seal or the fixing underneath is at fault. Monobloc mixers are held down by a bracket and a nut, or a threaded rod and nut, under the sink or worktop, and these work loose over years of use. Tighten the fixing from below so the tap sits firmly on its base seal. If the rubber base washer has perished or the sealant has broken down, water will run down the tap hole into the cupboard, where it can look like a pipe leak.

Water under the sink that appears when the tap is used is usually from the flexible tap connectors, the braided hoses between the tap tails and the pipework. A loose connection can be nipped up, but a hose that is bulging, rusty or has broken strands must be replaced before it bursts. Pull-out spray taps also have a hose and a counterweight under the sink, and the hose connection can leak when the spray is pulled out. Our guide to a leak under the kitchen sink goes through every joint in the cupboard.

Keep limescale in check once the tap is fixed. Unscrew the aerator on the end of the spout every few months and soak it in white vinegar or descaler to clear the mesh. A blocked aerator causes spray and back-pressure that works the cartridge harder. Our guide to hard water and limescale in London explains why Chelsea taps and fittings scale up so quickly and what helps.

Some taps are best left to a plumber. Replacing a cartridge on a mixer with a seized handle or shroud can crack the body if it is forced. Boiling-water taps have their own tank and electrical connection, and the manufacturer's instructions for isolating and servicing them should be followed; our guide to boiling water taps explains what sits under the sink. If the tap is old, heavily scaled or the parts are no longer available, replacing the whole tap is often simpler than chasing parts. Our general guide on how to stop a dripping tap covers older washer-type taps too. If the tap is past repairing, our guide to replacing a kitchen tap covers choosing a new one and how long the job takes.

A dripping kitchen tap wastes water all day and night, and if you are on a meter you pay for it. Our guide to how much water a leak wastes puts numbers on it. A leak that runs into the cupboard or the floor below is more urgent because it damages the kitchen units and can reach the ceiling of the flat underneath.

If the cartridge will not come out, you cannot find a matching part, or the tap is leaking into the cupboard and you cannot isolate it, call Emergency Plumber Chelsea on 020 3002 6667. Our leaking tap repair service replaces cartridges, O-rings, tap connectors and complete kitchen mixers across SW3, SW10, Knightsbridge, Sloane Square, South Kensington and Fulham. There is no call-out fee on jobs over 3 hours.

Quick tips

• Drip from the spout when off: worn or scaled cartridge. Leak round the spout base: worn O-rings.
• Isolate the tap with the valves under the sink and put the plug in before you start.
• Take the old cartridge with you to the merchant; a near match will not seal.
• Use silicone grease on tap O-rings, never petroleum-based grease.
• Descale the aerator every few months to reduce wear in hard-water London.

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