Mixer tap dripping from the spout
A dripping mixer tap is one of the most common plumbing niggles in UK homes, and the good news is it's usually fixable without calling out an expensive engineer. The culprit is almost always a worn ceramic cartridge inside the tap — a clever little component that controls hot and cold flow. Over time, mineral deposits from hard water or general wear cause the seal to fail, leaving you with that irritating constant drip that wastes water and drives up your bill. This guide walks through a straightforward DIY replacement that takes about 30 minutes and costs far less than a new tap. Most homeowners can handle this job with just a screwdriver and an Allen key. However, if your tap is very old, corroded, or you're uncomfortable working with water supplies, it's worth calling a qualified plumber rather than risking water damage.
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Most likely cause & what to check
Turn off the water supply under the sink — there should be isolator valves on both hot and cold supplies (turn the slot 90° to close). If there are no isolators, turn off at the mains stopcock.
Open the tap fully to release pressure and drain any remaining water in the pipes.
Remove the tap handles — there is usually a decorative cap on top hiding a screw (Phillips or Allen key). Remove the screw and pull the handle off.
Modern mixer taps use a ceramic cartridge — a cylindrical insert usually 35mm or 40mm in diameter. Unscrew the retaining nut and pull the cartridge out.
Take the old cartridge to a plumbers' merchant or DIY store to match it exactly — there are dozens of sizes. A replacement ceramic cartridge costs £5–£20.
Insert the new cartridge, ensuring it is oriented correctly (flow direction matters), retighten the retaining nut, replace the handle and turn the water back on slowly.
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Frequently asked questions
How much water does a dripping tap actually waste?
A single drip per second adds up to roughly 3,000 gallons per year — enough to fill an average bath several times over. Even a slow drip costs you real money on your water bill and is wasteful, so fixing it sooner rather than later makes sense both environmentally and financially.
Can I just replace the whole tap instead of the cartridge?
You can, but it's unnecessary expense and hassle. Replacing just the ceramic cartridge is significantly cheaper (£5–£20 versus £50–£200+ for a new tap), takes less time, and achieves the same result. Most mixer taps fail because of the cartridge wearing out, not because the tap body is damaged.
What if I can't find the exact matching cartridge?
This is rare — most taps use standard 35mm or 40mm cartridges that are widely available. Take a photo of your old cartridge or bring it with you to a plumbers' merchant; staff are usually very good at matching them. If your tap is extremely old or obscure, a new tap might be the only option.
Is a dripping tap a sign of a bigger plumbing problem?
In most cases, no — it's simply normal wear and tear on a common component. However, if multiple taps start dripping simultaneously, or if you notice low water pressure, there may be an issue with your mains supply or internal pipes that warrants a plumber's inspection.
Do I need to bleed air from the system after replacing the cartridge?
Usually not — opening the tap fully for a few seconds after turning the water back on is sufficient to clear any trapped air. If water splutters or comes out erratically for more than a minute, turn off at the isolator and wait 10 minutes, then try again.