Do this first
- Work out which tap and which water. Hot, cold, or both. If only the hot drips, the fault is on the hot side of a mixer or on the hot tap, which also tells you it is costing you heating as well as water.
- Look at where the water comes from. Out of the spout, or up around the base of the tap when it is running? Those are two different faults with two different urgencies.
- Isolate the tap. Most have small isolation valves on the tails under the basin or sink. A quarter turn with a flat screwdriver so the slot sits across the pipe closes it. If there are none, use the stopcock for cold and the cylinder or boiler isolation for hot.
- Open the tap fully once isolated to drop the pressure out of it.
- Dry the whole area inside the cupboard below, then put paper down and check it in an hour. Base leaks run down inside the unit and are usually older than anyone thinks.
- Do not force a stiff handle. On a ceramic cartridge tap, forcing it cracks the cartridge, and you go from a drip to a tap that will not shut.
Spout drip or base weep, and why the second is worse
| Symptom | Cause | What it costs you |
|---|---|---|
| Drip from the spout when closed, traditional tap with a turning handle | Worn rubber washer, or a pitted seat | Water only |
| Drip from the spout, quarter-turn or lever tap | Ceramic disc cartridge worn or scaled | Water only |
| Water appearing around the base of the tap while it runs, then drying | Body O-rings on a mixer, or the spout seal | Runs down inside the unit, unseen |
| Water under the cupboard with the tap off | Flexible tail, isolation valve or the back-nut seal | Continuous, and this is the damaging one |
| Drip that only happens shortly after the hot tap is used, from a vent or an overflow | An unvented cylinder expansion issue, not the tap | Needs a cylinder engineer |
A spout drip is a nuisance and a bill. A base weep is a building problem, because the water tracks down the tap body, through the mounting hole and into the carcass of the unit, where it sits on chipboard in the dark. By the time anyone notices, the base of the cupboard has swollen and the floor underneath it is wet. That is why a tap that only seeps when running is worth dealing with sooner than one that drips into the basin all day.
London water is hard, and scale is the reason most cartridges fail here, which is why changing a tap cartridge starts with matching the old one in the shop. It also means a washer that is replaced without dressing the seat will start dripping again within months, because the pitted brass seat cuts the new washer. If the cupboard under the sink is already wet, read a leaking pipe under the sink, because more than one thing in there may be leaking.
What the repair involves
A washer or cartridge change is isolate, strip, replace, reseat and test. On an older tap the seat is re-cut with a reseating tool rather than left pitted. On a mixer with a weeping base, the tap comes out of the worktop, the O-rings and the spout seal are replaced, and the back-nut and washer are renewed, which is also the moment to check the flexible tails, because braided tails have a service life and a rusting one is a burst waiting for a night when the house is empty.
Where the leak has already got into the unit and the floor, the job is bigger than the tap. We dry it, replace failed carcass panels or flooring, and reseal the worktop junction properly, which is the making-good half of water leak repair. Our rate for that work is set out on the pricing page.
When it is not us
- A standard washer or cartridge change. This is the classic homeowner job. Isolation valve, screwdriver, a matching cartridge, twenty minutes. Plenty of people do it themselves and should.
- A dripping outside tap in winter. Isolate and drain it before the freeze rather than repairing it in January.
- Water discharging from a pipe outside after the hot water runs. That is an unvented cylinder or a vented system behaving oddly, and it needs someone qualified on unvented systems.
- A tap that was only ever loose in the worktop. Tightening the back-nut fixes most of those.
- You rent. A dripping tap is a repair the landlord should be arranging, and it is worth reporting in writing because it wastes metered water you may be paying for.
- You want a new tap because you dislike the old one. That is a fit, not a repair, and any plumber can do it.