Faucet and sink repair, and the shut-off that should have worked

Why taps drip

A dripping faucet is a worn seal somewhere in the valve, and which seal depends on the type of tap.

Cartridge faucets, which is most modern single-lever and many two-handle designs, drip because the cartridge has worn. Replacement is straightforward, the part is inexpensive, and it usually restores the tap to as-new operation. The trick is identifying the correct cartridge, because they are model-specific and there are hundreds.

Compression faucets, the traditional design with separate hot and cold handles that tighten down, drip because the rubber washer at the end of the stem has worn or the seat it closes onto has become pitted. Both are repairable, a new washer, and the seat either dressed or replaced.

Ball and ceramic disc faucets have their own repair kits and seals.

The important point is that a drip is almost never a reason to replace the whole faucet. A cartridge or a washer costs a fraction of a new fixture, and on a good-quality tap it is by far the better purchase. Where replacement does make sense is when the body is corroded, the finish has failed, the model is obsolete with no parts available, or the tap has been repaired repeatedly.

Worth knowing: a drip that appeared alongside other symptoms across the house, fill valves failing, hoses bursting, may be a pressure problem rather than a wear problem. Check static pressure before replacing seals repeatedly. See water pressure problems.

Leaks under the sink

This is where the real damage happens, because a slow leak inside a closed cabinet is invisible until the base swells and the smell arrives.

Where to look, in order:

• The trap joints. Slip-joint connections loosen with movement and the washers harden. Usually a strip and re-make rather than just tightening.
• The tailpiece between the sink drain and the trap.
• The sink drain assembly itself, where the strainer or basket meets the sink, the putty or gasket seal fails and water runs down the outside of the pipe rather than dripping visibly.
• Supply connectors, particularly older braided or plastic ones, and the connections at the shut-off valves.
• The shut-off valve packing, which weeps once the valve is finally operated after years untouched.
• The faucet base, where water gets past the deck seal, runs down inside the cabinet, and looks exactly like a trap leak.

A dry paper towel test settles most of it: dry everything thoroughly, lay tissue at each joint, run water, and see which one wets first.

If the cabinet base is already soft, dark or swollen, mention it, the repair may need to include replacing that panel, and it is worth checking whether water has reached the subfloor beneath.

Slow or blocked sink wastes

Bathroom sinks block with hair bound together by soap and toothpaste, almost always in the pop-up stopper assembly or the trap immediately below it. Removing and cleaning the stopper linkage and the trap resolves the large majority, and it is genuinely the highest-yield thing a homeowner can do themselves.

Kitchen sinks block with grease, which is a different problem. Fat goes down warm, cools in the horizontal run, and builds up in layers that catch food debris. Cabling through it punches a channel that closes up again, which is why kitchen lines that block once tend to keep blocking. Removing the deposit properly means jetting: see hydro jetting.

A few useful distinctions. If the sink drains slowly and gurgles, and other fixtures are also affected, the problem is downstream in the branch or main rather than at the fixture. If it drains fine but smells, the trap may be dry or the vent may be blocked. And if a double sink drains into itself when one side is used, the blockage is below the tee between them.

Avoid caustic drain chemicals. They frequently fail on real blockages, they damage older metal pipe, and they leave the trap full of hazardous liquid that has to be dealt with before anyone can work. See drain cleaning.

Low flow at one tap

When one tap is weak and the rest of the house is fine, the cause is almost always within a foot of that tap.

The aerator is first. Unscrew it, and you will usually find the screen packed with mineral scale and grit. Soaking in descaler and rinsing restores full flow, and it costs nothing.

Isolation valves under the sink not fully open, which happens after any work in the cabinet.

A kinked or collapsed supply connector, particularly older plastic ones that have been pushed against by stored items.

A partially blocked cartridge, often after work on the mains or a repair elsewhere that has dislodged debris into the system.

Debris in the valve seat from a recent repair, flushing the line with the cartridge removed clears it.

If both hot and cold are weak at one tap it is usually the aerator or the cartridge. If only hot is weak at every tap, look at the water heater instead.

Seized shut-off valves

This deserves its own section because it is the thing that turns a fifteen-minute job into an afternoon.

The isolation valves under sinks and behind toilets are usually multi-turn valves installed decades ago and never operated since. The stem packing dries out, the internals corrode, and when someone finally tries to close one it either will not turn, will not seal, or snaps.

The practical consequence: a plumber arriving to change a faucet cartridge may find they have to shut the whole house down to do it, and the sensible recommendation is usually to replace the shut-offs while they are there. Quarter-turn ball valves are far more reliable than the old multi-turn design and cost very little.

It is genuinely worth doing proactively. Operating every isolation valve in the house once a year keeps them free, and identifies the seized ones at a moment of your choosing rather than during an emergency. The same applies to the main shut-off. Find it, turn it, make sure it works, before you need it at two in the morning.

Replacing a faucet

Replacement makes sense when the body is corroded, the finish has failed, parts are no longer available, or the fixture has been repaired more than once or twice.

What a proper job includes: checking the new fixture matches the hole configuration in the sink, single hole, three-hole with the standard four-inch centres, or widespread eight-inch, because these are not interchangeable. Removing the old unit, which in an old kitchen frequently means dealing with corroded nuts in a space nobody can reach. Fitting new supply connectors rather than reusing the old ones. Replacing the shut-offs if they are questionable. Sealing the deck properly so water cannot get underneath. Then testing under pressure and checking for movement.

Where a sink is being replaced as well, the drain assembly, tailpiece and often the trap arrangement need renewing to match, and if the new bowl is a different depth the whole trap geometry may change.

Choosing fixtures that last

The single most useful thing to look for is a solid brass body rather than plastic or zinc, and a ceramic disc or good-quality cartridge valve. Those two features account for most of the difference between a faucet that lasts twenty years and one that starts dripping in three.

Second, check parts availability. A well-known brand with a long-standing cartridge design means you can buy a seal in ten years; a discount fixture with a proprietary cartridge means the whole unit gets replaced when it fails.

Third, be realistic about finish. Chrome is the most durable and easiest to keep. Brushed and satin finishes hide water spots well. Living finishes are intended to change and will. And matte black, whatever its current popularity, shows limescale in hard-water areas.

Finally, match the fixture to the water. In areas with hard water, ceramic disc valves and simple aerator designs cope far better with scale, and a fixture with intricate internal passages will clog. If your water leaves deposits on everything, that is worth factoring in: see water treatment and filtration.