Tap Leaking From the Base? Causes and How to Fix It

A tap leaking from the base is usually caused by worn O-rings where the spout swivels, a failed seal on the cartridge inside the tap body, or a tap that has worked loose on the worktop or basin. On a kitchen mixer, water that appears round the base when the tap is running, and gets worse when you move the spout, almost always means the spout O-rings have gone. If the puddle is there even when the tap hasn't been used, the leak may be underneath, from a hose or joint, and only look as if it's at the base. Finding exactly where the water starts takes a few minutes and tells you which part needs replacing.

Find where the water is coming from

Dry the tap, the worktop and the cupboard underneath with kitchen roll first. Then work through these checks, looking each time for the first place water appears.

When and where you see water	Most likely cause
Round the base only while the tap runs, worse when the spout moves	Worn spout O-rings
Seeping from under the handle or lever, then running down	Cartridge seals or headgear O-ring
From a crack or pinhole in the tap body	Damaged tap body; the tap needs replacing
Tap rocks or turns on the worktop, water gets under the base plate	Loose fixing nut or worn base gasket
Water in the cupboard, or on the worktop when the tap is off	Flexible hose, isolation valve or pipe joint underneath
Water round the base after washing up, nowhere else	Splashes getting under a worn base seal, not a leak

A useful test is to leave the tap off for an hour with dry kitchen roll wrapped round the base and laid in the cupboard below. If the paper underneath is wet and the paper round the base is dry, the leak is below the worktop.

Why a tap leaks from the base

Inside most modern taps, water is kept in by rubber seals: O-rings round the spout and the cartridge, and a washer or gasket under the base. They harden, wear and pick up grit over time. London's hard water speeds this up because limescale forms on the metal surfaces the O-rings slide over, which scores the rubber every time the spout moves or the handle turns.

When a seal fails, water under pressure finds the nearest way out. On a mixer that's usually round the base of the spout or under the handle. Because the water runs down the outside of the tap, it collects at the base, which is why so many different faults end up looking like the same leak.

Kitchen mixer taps

• Swivel spout O-rings. Most kitchen mixers have a spout that sits over the tap body and turns on two or three O-rings. Every swing of the spout wears them. The tell-tale sign is water seeping out round the base of the spout only when water is flowing through it, and more when you move it side to side. This is the most common cause of a mixer tap leaking from the base, and a straightforward repair.
• Cartridge seals. Single-lever mixers control flow and temperature with a ceramic cartridge. If its O-rings or base seal fail, water escapes past the cartridge and out under the lever. Often the tap also starts to drip from the spout or feel stiff.
• Pull-out and spray taps. The hose connection inside the body or under the sink can leak and track water to the base.
• A loose tap. Monobloc taps are held down by a nut or threaded rod under the worktop. If it works loose, the tap moves, the base seal lifts and splashes get underneath. Tightening it from below usually fixes this.

If the mixer is old or the body is damaged, replacement may be simpler. Our guide on how to replace a kitchen tap walks through it, and our kitchen tap repair service covers both.

Basin and bath taps

On pillar taps (separate hot and cold taps), water round the base usually comes from higher up. A worn O-ring or gland packing round the spindle lets water out under the handle when the tap is on, and it runs down the body. On older rising-spindle taps, tightening the gland nut a little can stop it; otherwise the O-ring needs replacing.

Basin and bath mixers behave like kitchen mixers: cartridge seals, swivel spouts on some bath fillers, and loose fixings. On a bath tap, a leak at the base is worth sorting quickly, because water can run behind the bath panel and into the floor without being seen.

If the tap also drips from the spout, see our guide on how to fix a dripping tap. If it won't shut off properly, see tap won't turn off.

How to fix it

1. Isolate the water. Turn the isolation valves on the hot and cold pipes under the sink a quarter turn with a flat-head screwdriver so the slot sits across the pipe. If there are none, close the main stopcock. Open the tap to release the pressure. The Water Fittings Regulations define these servicing valves for exactly this purpose: shutting off one fitting for maintenance without turning off the whole house.
2. Plug the sink. Put the plug in so small parts can't fall down the waste.
3. For spout O-rings: find the grub screw or collar holding the spout (often at the back or under a cap), loosen it and lift the spout off. Cut the old O-rings off the tap body, clean any scale off the grooves and fit new ones of the same size. A thin coat of tap-safe silicone grease helps them slide and seal. Refit the spout.
4. For cartridge seals: remove the handle (usually a hidden screw under a cap), unscrew the shroud and the cartridge retaining nut, and take the cartridge out. Replace its O-rings if they're available, or replace the whole cartridge with an identical one. Take the old one with you to match it.
5. For a loose tap: tighten the fixing nut under the worktop, checking the tap is straight first. Replace the base gasket if it's perished.
6. For leaks underneath: check the flexible hoses for kinks, rust spots or weeping at the ends, and check any isolation valves and compression joints. Our guides to a leak under the kitchen sink and a leaking compression fitting cover these.
7. Turn the water back on slowly and check for drips with dry kitchen roll.

Don't overtighten anything. Brass and plastic parts crack easily, and a cracked tap body can't be repaired.

When to call a plumber

Call a plumber if you can't find or match the parts, if the spout or cartridge won't come off because of scale, if the isolation valves won't turn or don't fully stop the water, if the tap body is cracked, or if water has got into the worktop or cupboard base. It's also worth calling if more than one tap has started leaking, as that can point to high water pressure or heavy scale through the system.

We charge £95 an hour for labour, plus a £60 call-out that's waived when the job runs over 2 hours. Parts are extra and we confirm the price before any work starts. Our tap repair and kitchen tap repair services cover homes and flats across London, and the pricing page explains how jobs are charged.

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