What Actually Causes a Dripping Tap (By Tap Type)
The dripping tap is plumbing's most familiar fault and its most commonly misdiagnosed — because the fix depends entirely on which of three internal designs you own, and they look similar from outside. Two seconds of handle-turning identifies yours, and the worn part follows from there.
Identify the type in two seconds
Turn the handle. Multiple full rotations to open and close: a compression tap, sealed by a rubber washer squeezed onto a brass seat. A quarter or half turn between off and full: ceramic disc, sealed by two polished ceramic plates in a cartridge. A single lever mixing hot and cold: a mixer cartridge, ceramic internals plus mixing function. Each drips from a different part, which is why 'I changed the washer and it still drips' is usually a type mismatch, not bad luck.
Compression taps: washer and seat
The washer hardens, splits or compresses flat, and water threads past — the classic drip. Replacement is genuine DIY territory with isolation available. The complication: a scored or scaled brass seat beneath, which chews new washers in weeks. Persistent dripping after fresh washers means the seat needs reseating (a cheap grinding tool) or a seat insert. In hard-water areas the seat scales faster and this second-stage fault is common.
Ceramic disc and mixers: the cartridge
Ceramic plates don't wear like rubber, but scale scores their polished faces and grit chips them — and once the mating surfaces are compromised, they weep. The fix is a replacement cartridge matched by diameter, height and spline pattern; there is no washer to change. Mixer drips from the spout follow the same logic, while leaks around the base of a swivel spout are O-rings on the spout column instead — a different, cheaper fix often mistaken for cartridge failure.
The drips that aren't the tap
Water appearing below the tap isn't always the tap: weeping flexi connectors, a loose base gasket letting sink water through the tap hole, or condensation on cold pipework in humid kitchens all impersonate a leak. Dry everything, lay kitchen towel, and watch where moisture returns first. Flexi connectors deserve suspicion at any age — they're the most common genuine flood source under a sink, and replacing them during any tap work is cheap insurance.
| Tap type | Wear part | Second-stage fault |
|---|---|---|
| Compression (multi-turn) | Rubber washer | Scored seat — reseat/insert |
| Ceramic disc (quarter-turn) | Cartridge | Scale-scored plates |
| Single-lever mixer | Mixer cartridge | Spout O-rings (base leaks) |
| Any — water below, not at spout | Flexi connectors / base gasket | Replace flexis proactively |
If the symptoms don't quite match
Faults read textbook-clean in guides and messier in airing cupboards: if your symptoms straddle two patterns above or match none cleanly, that ambiguity is itself useful diagnostic information — tell the engineer precisely that. Intermittent faults deserve a log (time, conditions, what preceded it) because patterns invisible in one visit leap out of a week's notes. And any symptom involving escaping water you can't isolate upgrades itself to the emergency line.
Frequently asked questions
Why does my quarter-turn tap drip when I changed the washer?
Quarter-turn taps don't have serviceable washers — they seal with a ceramic cartridge, and that's the worn part. The washer you changed wasn't the sealing component.
Are tap cartridges universal?
No — they vary by diameter, height, spline count and handedness. Matching against the removed cartridge (or the tap brand) is routine; guessing is how online orders go two rounds.
How urgent is a slow drip?
Not an emergency, but a compounding cost: thousands of litres a year, billed twice on a meter, plus permanent scale staining below in hard water. A standard booking soon beats a someday job.
Should flexi hoses be replaced on a schedule?
Treat them as a 10-year consumable, and replace during any tap work regardless. Burst flexis are a leading cause of kitchen floods, and they fail without ceremony.
Sorting it for good
The recurring theme across our guides holds here too: fix causes, not symptoms. A repair that addresses why the fault happened — the pressure that's too high, the scale that keeps returning, the valve that should have been replaced a decade ago — is the one you don't repeat next year. When you book through our network, tell the engineer you want the cause addressed, not just the symptom silenced; it occasionally costs a little more on the day and reliably costs less over the years.