Kitchen Mixer Tap Leaking at the Base

On top, in between or underneath: find the leak first

Kitchen taps get more use than any other tap in the house, and they are moved, pulled and knocked all day. That is why the base is where they fail. Before buying anything, work out exactly where the water starts, because the three causes look similar from a distance and need completely different parts.

Empty the cupboard under the sink and dry everything: the tap, the sink rim around it, the hoses, the isolation valves and the cupboard floor. Lay a sheet of kitchen paper flat under the hoses. Then run the tap hot and cold for a minute, swing the spout from side to side, and look again.

• Water appears around the ring where the spout meets the tap body, mainly when running or swinging: spout O-rings.
• Water creeps out from under the tap body onto the sink or worktop, and the tap may wobble: the base seal or a loose fixing.
• The kitchen paper under the sink is wet, the worktop is dry: a flexible hose, its connection into the tap, or an isolation valve.
• Water only appears on the worktop after washing up, not after running the tap: splashing past failed sealant round the sink, not the tap.

Water in the cupboard: the flexible hoses

Most modern kitchen mixers are monobloc taps fed by two flexible braided hoses, often called tap tails. One end screws by hand into the base of the tap body, usually with a small rubber seal or O-ring on a fine metric thread. The other end usually has a 15 mm compression or push-fit connection, or a threaded nut, onto the copper pipe or the isolation valve.

A leak at the top of the hose, where it enters the tap, is often a hose that was cross-threaded or over-tightened when fitted, which crushes the little seal. A leak at the bottom is usually the compression nut or the valve. A leak from the braid itself, sometimes a fine spray or a bulge in the hose, means the inner rubber has failed and the hose is close to bursting.

Check the braid for rust spots, fraying or kinks. Cleaning products kept in the cupboard, especially bleach, can corrode the stainless braid over time. A hose showing any of that should be replaced, not tightened. If a hose looks sound and the drip is at a nut, close the isolation valve and nip the nut a quarter turn. Do not keep tightening a compression nut that still weeps; the olive inside needs remaking. More on this in a pipe leak under the sink.

A braided hose that has burst puts out water at full mains pressure. If a hose is bulging, spraying or badly rusted, close its isolation valve or the stopcock now and leave the tap off until the hose is changed.

Water round the spout collar

If the leak is on top, at the ring where the swivel spout sits on the body, the O-rings sealing the spout have worn. Kitchen taps suffer this more than basin taps because the spout is moved so often. It gets worse in hard water, as scale on the body cuts the rubber each time the spout turns.

The fix is new O-rings, usually two or three, fitted with a thin coat of silicone grease made for taps. The spout is held by a grub screw at the back of the collar or by a threaded ring at its base. The step-by-step, and how to tell an O-ring leak from a cartridge drip, is in mixer tap leaking: cartridge or O-ring.

Pull-out and pull-down spray taps have one more weak point: the spray hose runs down through the tap body and joins the supply under the sink, often with a weight on the loop. A leak from that joint shows up as water in the cupboard only when the spray head is in use.

Water from under the tap body and a wobbling tap

Between the tap body and the sink or worktop there is a rubber or foam base gasket, sometimes with an O-ring in a groove on the underside of the tap. Its job is to stop splashed water running down through the tap hole into the cupboard. When the tap works loose, the gasket stops sealing and water finds a way through, and the tap starts to turn or rock as you use it.

Underneath, the tap is held by one or two threaded studs, or a single large threaded shank, with a horseshoe-shaped plate and a nut or two. Tightening those nuts from below usually cures both the wobble and the leak. Reaching them in the back of a cupboard behind a sink bowl is the hard part. A basin wrench or a long-reach tap spanner makes it possible without taking the tap out.

If the gasket is split or flattened, the tap has to come off. Close both isolation valves, undo the hoses from the valves, loosen the fixing from below and lift the tap out, hoses and all. Fit a new base gasket, clean the sink around the hole, and refit. Do not simply run a bead of silicone round the outside of the base: it hides the leak for a while and makes the next repair harder.

When a kitchen tap leak needs someone tonight

A slow drip at a tap collar can wait. Call someone out if water is running into the cupboard faster than a drip, if a hose is bulging or spraying, if the isolation valves will not shut, or if the chipboard base of the cupboard or the floor under the units is already wet. Chipboard swells and does not recover, and water under fitted units spreads a long way before it shows.

If you have a boiling-water tap or a filter tap, there is a tank or cartridge unit in the cupboard as well. Isolate it at its own valve and switch off its electrical supply before you look. Its internal parts are the maker's service job, not a general plumbing one.

As a typical market guide, a pair of braided tap hoses costs roughly £5 to £15, an O-ring kit a few pounds, and a mid-range kitchen mixer from about £50 to £200.

Our leaking tap repair visit is a £60 call-out at any hour, and the repair price is agreed with you on site before any work starts. The engineer finds the source, replaces the failed hose, seal or O-rings, and runs the tap hot and cold with the cupboard dry to prove it. If water has spread under the units, see a leak under a bathroom sink for how to dry out and check the damage; the same steps apply in a kitchen.