Basin Mixer Tap Dripping (Cartridge vs Washer — How to Tell and DIY Fix)
A dripping basin mixer tap is one of the most common plumbing niggles in UK homes, and the good news is that it's usually fixable without calling a plumber. The culprit is almost always a worn internal component — either a ceramic disc cartridge (in modern taps) or a rubber washer (in older models) — and both are inexpensive to replace. The annoying part is that a slow drip can waste thousands of litres of water annually and drive up your bills, but the encouraging part is that identifying which type you have and making the repair yourself takes less than an hour and costs just a few pounds. This guide walks you through diagnosing your tap type, sourcing the right replacement part, and carrying out the fix safely. If you're not confident with spanners or your tap shows signs of corrosion or damage to the body itself, that's the point to ring a qualified plumber.
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Most likely cause & what to check
The first step is to determine whether your basin mixer uses ceramic disc cartridges or traditional rubber washers. Ceramic disc taps are the modern type — the handle rotates approximately 90 degrees from off to fully open. Traditional washer taps (also called "stem" or "compression" taps) require multiple full turns of the handle from off to fully open. Most basin mixers installed in the UK since 2000 use ceramic discs. Quarter-turn taps are always ceramic disc; any tap that requires more than a full turn is almost certainly a washer type.
For a ceramic disc basin mixer: turn off the water at the isolation valves (the slotted screws under the basin — a quarter turn closes them). Remove the handle cap (prise off or unscrew) and expose the retaining screw. On single-lever monobloc taps this is usually an Allen key screw; on two-handle taps it may be a Phillips screw. Remove the screw and lift the handle. The ceramic cartridge is now visible, held by a retaining nut or collar. Unscrew this and pull out the cartridge.
Inspect the ceramic cartridge: cracked ceramic discs are visible as fine dark lines or chips, and the cartridge may feel gritty when you rotate the ceramic discs against each other. Replacement cartridges are available from Screwfix (Flomasta brand cartridges are good value at £5–12), Toolstation, Plumb Center, or from the tap manufacturer. Match the diameter (typically 25mm, 35mm, or 40mm for basin mixers), the height, and the spindle type (some have flat-sided spindles, others are round). When in doubt, take the old cartridge to a merchants and match it by eye.
For a traditional washer basin mixer (more common in pre-1990 UK bathrooms): shut off the water and open the tap to drain. Remove the handle (multiple turns of a cross-head handle, then remove the retaining screw underneath). Unscrew the headgear using an adjustable spanner — this is the large brass nut above the tap body. At the base of the headgear stem you will find the rubber washer held by a small brass nut (the jumper nut). Replace the washer with a 1/2" tap washer (packs from Screwfix for £2). If the washer looks fine but there is still a drip, the tap seat may be scored and needs regrinding.
On two-handle basin mixer taps (one for hot, one for cold), each handle has its own cartridge or washer and either or both can be the source of a drip. To identify which is leaking: close one handle at a time with the other open, and see if the drip stops. Whichever handle being closed stops the drip is the faulty side. Replace that cartridge only — though it is good practice to replace both at the same time to save a repeat job.
After replacing the cartridge, refit the retaining nut (hand tight plus a quarter turn — no more), refit the handle and screw, then restore the water supply slowly and test. If the tap still drips after a new cartridge, or if the body of the tap is corroded or the spout is dripping from the base rather than the outlet, these indicate problems beyond a simple cartridge fix. A damaged tap seat (rare on modern taps) or a corroded spout O-ring are the most likely culprits and both are relatively straightforward to address — or it may be time to replace the tap entirely, which for a basic basin mixer is a £20–80 job at Screwfix or Victorian Plumbing.
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Frequently asked questions
How do I know if my basin tap has a ceramic cartridge or a rubber washer?
The quickest way is to turn the handle. If it moves a quarter-turn (90 degrees) from off to fully open, it's a ceramic disc cartridge — the modern standard in UK homes since around 2000. If the handle needs multiple full rotations, it's a traditional washer tap, commonly found in properties built before 1990. Quarter-turn taps are always ceramic; anything requiring more than one full turn is almost certainly a washer type.
Can I fix a dripping tap myself, or do I need a plumber?
Most dripping basin mixer taps can be fixed as a straightforward DIY job if you're reasonably handy with basic tools — you'll typically only need an adjustable spanner, an Allen key, and a screwdriver. The cartridge or washer replacement itself takes 20–30 minutes. However, if the tap body is corroded, the spout is leaking from its base, or you're uncomfortable working under the basin, it's worth calling a professional rather than risking water damage.
How much does it cost to fix a dripping basin mixer tap?
A replacement ceramic cartridge costs between £5 and £12, and a pack of rubber washers costs around £2 — so parts are very cheap. If you do it yourself, you'll spend only a few pounds. If you call a plumber, expect a callout fee of £50–150 plus the cost of parts, though many will charge a flat rate of £100–200 for a straightforward cartridge or washer swap.
Will replacing the cartridge fix the drip, or might I need a new tap?
In the vast majority of cases, a new cartridge or washer will stop the drip completely — it's the most common cause. If the drip persists after replacement, or if you notice corrosion on the tap body or water leaking from the base of the spout, the tap seat or spout seals may be damaged, and replacement of the entire tap (£20–80 for a basic model) is usually the most cost-effective solution.
My two-handle tap is dripping — which handle do I need to fix?
Test each handle individually: close the hot handle and open the cold (or vice versa) and note whether the drip stops. Whichever side you close that stops the leak is the faulty one — that's the cartridge or washer you need to replace. It's good practice to replace both at the same time to avoid a repeat repair in a few months.
Where can I buy a replacement cartridge or washer in the UK?
Replacement cartridges and washers are widely available from Screwfix, Toolstation, Plumb Center, and most independent plumber's merchants. You can also order directly from tap manufacturers if you know the brand. Taking your old cartridge to a merchant and matching it by eye is the safest approach if you're unsure of the exact specifications.