A dripping tap is one of the most common plumbing calls we receive. It is also one of the most frequently misdiagnosed by homeowners — because the assumption is almost always that the washer needs replacing. In a significant proportion of modern taps, there is no washer at all. The tap uses a ceramic disc cartridge, and fitting a washer will make no difference whatsoever.
This guide is written to help you correctly identify your tap type, understand the difference between the two main mechanisms used in UK homes, and diagnose why your tap is still dripping even after you have already attempted a repair.
Two Types of Tap: Compression vs. Ceramic Cartridge
Almost all taps in UK homes use one of two internal mechanisms. Identifying which type you have before attempting any repair is essential.
Compression Washer Tap
The traditional UK tap mechanism. A rubber or fibre washer is compressed against a brass seat to stop water flow. Turning the handle clockwise screws the washer down onto the seat; turning anticlockwise lifts it to allow flow.
How to identify: Handle requires multiple full rotations to open/close. You can feel resistance building as you tighten. Common in cross-head taps and older pillar taps.
Wearing part: Rubber washer (and the brass seat it presses against).
Ceramic Disc Cartridge
The standard mechanism in virtually all taps manufactured after approximately 1990. Two precision-ground ceramic discs rotate against each other. When aligned, water flows; when offset, the flow is sealed. No rubber washer is involved.
How to identify: Handle opens/closes with a quarter-turn or half-turn. Lever taps are always ceramic. Many modern pillar taps are also ceramic.
Wearing part: The cartridge unit itself (discs + O-ring seals).
Why Is the Tap Still Dripping? Diagnostic Table
Use this table to match your situation to the most likely cause:
| Situation | Most Likely Cause | Fix |
|---|---|---|
| Dripping from spout after washer replacement | Tap is ceramic cartridge type — washer irrelevant | Replace ceramic cartridge |
| Dripping from spout — washer replaced, still drips | Pitted or corroded tap seat | Regrind seat or replace tap |
| Dripping from base of spout (not tip) | Worn O-ring on spout or cartridge body | Replace O-ring or cartridge |
| Lever tap dripping — quarter-turn handle | Ceramic disc cracked or scaled | Replace ceramic cartridge |
| Water leaking around handle base | Gland packing or O-ring on valve stem | Repack gland or replace stem O-ring |
| Monobloc kitchen mixer dripping from spout | Ceramic cartridge (hot or cold side) | Identify which side and replace cartridge |
| Dripping persists after new cartridge fitted | Wrong cartridge size/brand, or damaged tap body | Verify cartridge spec or replace tap |
Ceramic Cartridge Failure in Hard Water Areas
Ashford and the surrounding villages in Kent sit in a hard water zone. The water supply carries a high concentration of dissolved calcium and magnesium, which deposits as limescale on any surface it contacts. Ceramic disc cartridges are particularly susceptible because the precision fit between the two discs relies on a perfectly smooth sealing surface. Even a thin layer of scale on the disc face is enough to prevent a clean seal and cause a persistent drip.
Scale build-up also affects the O-ring seals around the cartridge body, causing them to harden and crack. This produces a drip from the base of the tap body rather than the spout tip — a fault that is often misidentified as a spout drip.
Limescale tip: When replacing a cartridge in a hard water area, soak the tap body interior with a descaling solution before fitting the new cartridge. This removes residual scale that would otherwise score the new ceramic discs within months.
When to Call a Plumber for a Dripping Tap
A straightforward cartridge replacement on an accessible tap is within reach of a careful DIYer. However, there are several situations where professional help is the right call:
- The tap is a branded unit (Grohe, Hansgrohe, Bristan, Ideal Standard) requiring a proprietary cartridge that is not available at a general plumbing merchant.
- The isolation valve under the sink is seized and will not close — attempting to force it can cause a burst pipe.
- The tap body itself is corroded, cracked, or the thread is damaged — no cartridge replacement will fix a structurally compromised tap.
- The tap seat (in a compression washer tap) is pitted and needs regrinding with a specialist tool.
- The drip is coming from the supply pipework behind the wall rather than the tap itself.
Our fixed-price tap repairs and replacements cover all tap types — from a simple cartridge swap on a pillar tap to a full monobloc kitchen mixer replacement. We carry a wide range of cartridges in the van and can usually complete the repair on the first visit.