How to replace a tap washer
⚠️ Always turn off the water supply before starting.
A dripping tap is one of the most common household problems, yet it's also one of the easiest to fix yourself. That irritating constant drip usually stems from a worn rubber washer that's lost its seal, or occasionally from a damaged valve seat underneath. Most homeowners notice the problem first as a steady drip into the sink, which not only wastes water but can also drive the household bills up surprisingly quickly. This guide walks you through replacing the washer on a traditional two-handle tap — a straightforward job that typically takes 15–20 minutes and costs just a few pounds in parts. If you discover the valve seat is heavily pitted or corroded during the process, you may need to invest in a reseating tool or call a qualified plumber to assess whether the entire tap needs replacing.
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Most likely cause & what to check
Turn off the isolating valve under the sink (or the main stop tap). Open the tap to drain remaining water.
Prise off the decorative cover cap on the top of the tap handle.
Unscrew the retaining screw beneath the cap and lift off the tap handle.
Use an adjustable spanner to unscrew the headgear (the hexagonal brass nut below the handle). Turn anti-clockwise.
At the bottom of the headgear, you'll find the rubber washer — replace it with a matching size.
If the seat (the brass ring the washer presses onto) is pitted or damaged, regrind it with a tap reseating tool or replace the headgear entirely.
Reassemble in reverse order. Turn on the supply slowly and test for drips.
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Frequently asked questions
How much water does a dripping tap actually waste?
A tap dripping just once per second wastes roughly 3,000 litres per year — enough to fill a small swimming pool. Over a few months, this can add a noticeable amount to your water bill, so fixing it promptly makes both environmental and financial sense.
Can I replace a tap washer without turning off the water?
No — always isolate the water supply first, either at the isolating valve under the sink or at the main stop tap. Attempting this without isolation will result in water spraying everywhere and you won't be able to work safely.
What size washer do I need, and where do I buy one?
Tap washers come in standard sizes (typically 12mm or 16mm diameter), and the old washer will tell you which you need. Any plumber's merchant, DIY superstore, or even some hardware shops stock assorted washer kits for a few pounds — no special order necessary.
What if the tap still drips after I've replaced the washer?
The most likely culprit is a damaged or pitted valve seat — the brass ring underneath that the washer sits on. You can either use a tap reseating tool (a specialised bit of kit) to smooth it, or if it's badly damaged, consider replacing the entire headgear or calling a plumber for advice.
Do modern taps need washers replaced the same way?
Modern cartridge or ceramic disc taps work very differently and don't use traditional washers — they require cartridge or disc replacements instead. This guide applies specifically to older two-handle taps with headgear; if your tap is newer, it's worth checking the manufacturer's instructions.
How often should tap washers be replaced?
With normal use, a tap washer typically lasts 4–8 years before wear causes dripping. If you have particularly hard water, washers may wear faster, so don't be surprised if you need to repeat this job every few years on heavily used taps.