How to stop a dripping tap in fifteen minutes

Turn the water off first. Everything that follows is recoverable. A tap head unscrewed under mains pressure isn't, and you'll find out how fast a bathroom floods while you're on your knees looking for a stopcock you've never touched.

Most dripping taps come down to a rubber washer about 15mm across, or a ceramic cartridge the size of a chess pawn. Both cost less than a takeaway. The skill isn't the swap. It's getting the tap apart without cracking the basin, and getting it back together without a weep round the base.

Fifteen minutes is realistic on the second tap you ever do. Budget forty on the first, plus a trip to the merchant.

Work out what's actually leaking

Watch the tap for a minute before you touch anything.

Water dripping from the spout with the tap shut off. That's the washer or the ceramic cartridge inside the valve. This is the job below.

Water seeping out round the base of the handle, or under the spout collar on a mixer, when you run it. That's an O-ring, not a washer. Same strip-down, different part.

A puddle in the cupboard under the basin. Stop. That's a supply connection or the tails, and tightening the wrong thing makes it worse. Dry everything with kitchen roll, run the tap, and watch where the first bead forms.

A dripping spout on a quarter-turn tap (handle moves 90 degrees, stops dead) means a ceramic cartridge. There's no washer to change. You replace the whole cartridge or you replace nothing.

If the handle spins a full turn or more before the water stops, it's a traditional compression tap with a rubber washer. Those are the forgiving ones.

Isolate the water

Open the cupboard under the basin and look at the two pipes feeding up to the tap tails. On anything plumbed in the last twenty-odd years you'll find a small chrome isolating valve on each, with a slot for a flat screwdriver. Slot in line with the pipe means open. Turn it a quarter turn so the slot sits across the pipe. That's closed.

No isolating valves? Find the stopcock. Kitchen sink cupboard is the usual spot, sometimes the utility, sometimes under the stairs. Turn it clockwise until it stops. If it's stiff and hasn't moved in a decade, don't force it with a wrench and shear the spindle. That turns a fifteen-minute job into a plumber's morning.

Now open the tap you're fixing and leave it open. Water will run for a few seconds and then stop. If it doesn't stop, you've closed the wrong valve.

Two more things before you pick up a spanner. Put the plug in, or stuff a cloth in the plughole. Grub screws are small, round and gone forever. And lay a towel in the basin so a dropped spanner doesn't chip the ceramic.

Get the handle off

This is where people give up, because the fixing is hidden.

On most basin taps there's a plastic index cap on top with a red or blue dot. Wrap a small flat screwdriver tip in a strip of insulating tape and prise the cap up from the edge. Some unscrew by hand instead, anticlockwise, so try twisting before you lever.

Underneath is a screw. Usually a cross-head, sometimes a 2.5mm hex grub screw set into the side of the handle instead. Undo it and keep it somewhere that isn't the basin.

Lift the handle straight up. If it's welded on with limescale, a few drops of penetrating oil round the spindle and five minutes of patience beats brute force. Rocking it side to side while pulling up usually frees it.

Then the shroud, the chrome cover under the handle. Hand-tight most of the time. If it needs a spanner, wrap it in a cloth first or you'll leave jaw marks on the chrome that you'll look at every morning for the next ten years.

The bit where taps get broken

Under the shroud is the headgear, a brass hexagon. On older taps you'll want a 19mm spanner or a decent adjustable.

Before you turn it, hold the tap body still with your other hand or a second spanner. This matters more than anything else in the job. All the force you put into that hexagon goes down through the tap body into the basin. Crack a ceramic basin and you've spent a weekend and a few hundred pounds on a dripping washer.

Undo anticlockwise. It'll be tight, then suddenly free. Lift the headgear out.

Compression tap. On the bottom of the headgear is the jumper valve with the rubber washer, either pressed on or held by a small brass nut. Prise the old washer off. Half-inch washers fit basin and kitchen taps; three-quarter is for bath taps. Take the old one with you to the merchant if you're unsure, because "half inch" refers to the tap, not the measurement across the rubber.

Ceramic tap. The whole cartridge lifts out. Cartridges are handed, so the hot and cold aren't interchangeable and fitting the wrong one gives you a tap that turns the wrong way and still drips. They also vary by spline count and body size between makes. Take the old one to the counter and match it physically. Don't order by photograph.

Put it back better than you found it

Wipe the seat inside the tap body with a cloth on your finger. Grit and limescale scale sit in there and a new washer on a scaly seat drips within a week.

Run a smear of silicone grease on the headgear thread and on any O-rings. Silicone, not petroleum jelly, which swells rubber over time.

Screw the headgear back in by hand until it seats, then nip it up with the spanner and stop. Maybe a quarter turn past snug. Overtightening a compression tap crushes the new washer flat against the seat and you'll be doing this again by Christmas.

Handle on, screw in, index cap pressed back down.

Open the isolating valve slowly, a quarter turn at a time, with the tap itself half open so air can escape. It'll splutter, spit, then run clean. Shut the tap and watch the spout for a full minute.

When the drip comes back

A new washer that still drips means the brass seat inside the tap body is pitted. You've got two options: a re-seating tool, which cuts the seat flat again, or a nylon seat washer that sits over the damage. Both are cheap. Both are a second visit to the merchant, which is why experienced hands buy a seating kit at the same time as the washers.

If the headgear won't budge after penetrating oil and a proper spanner, leave it. Old brass shears, and a sheared headgear inside a tap body on a Sunday evening is a new tap and a plumber.

And if you find the basin moving when you tighten anything, the back nut underneath has worked loose. Fix that before you fix the drip, or you'll be doing both again.

Keep the old washer in the drawer. Next time a tap in the house starts ticking at two in the morning, you'll already know what size it takes.