A dripping tap seems harmless until you see the water bill, or the swelling of the cabinet base. Left alone, a small leak can waste thousands of litres a year, stain fittings, and eventually cause mould or damage to worktops and floors. The good news: most leaking tap fixes are simple, cheap, and doable in under an hour with basic tools. Here’s how to spot the problem early, diagnose it properly, and fix it confidently before it drains your wallet.
Why A Leaking Tap Matters: Costs, Damage, And Waste
A steady drip can waste 5–15 litres a day, hundreds a month. That’s money down the drain and needless strain on water supplies. If you’re on a meter, a single leaking tap can add tens of pounds each billing cycle: multiple leaks or high-pressure drips can rack up much more over time.
It’s not just the bill. Constant moisture leaves limescale trails, pits chrome, and encourages mould on silicone and timber. Under-sink leaks wick into chipboard and MDF bases, causing swelling and warping. On stone or enamel surfaces, mineral deposits create stubborn stains that need harsher cleaning (which wears finishes faster). And if your tap is part of a mixer, hot-side drips waste energy, too.
Fixing a leaking tap typically costs a few pounds for washers or seals, far less than a new mixer, never mind repairing a swollen worktop.
How To Diagnose The Leak: Where, When, And How Much
Identify Your Tap Type
Before you can fix anything, know what you’ve got:
- Compression (rubber washer): Separate hot and cold handles that turn multiple times. Classic culprit for drips.
- Cartridge: Quarter-turn handles: smooth on/off. Uses a replaceable cartridge (often hot and cold specific).
- Ceramic disc: Similar to cartridge: two ceramic plates control flow. Usually quarter-turn, reliable but can jam with grit.
- Ball mixer: Single lever with a rounded dome cap: common on older mixer taps. Uses a ball and springs/seals.
Check for brand markings under the handle cap or on the spout. A quick photo compared against the manufacturer’s website can confirm parts.
Pinpoint The Source: Spout, Base, Or Handles
- Spout drip (after shutting off): Usually a worn washer (compression), a failed cartridge/disc, or debris on the sealing surfaces.
- Drip from the handle: Think O-rings or gland seals around the spindle or cartridge stem.
- Leak at the base or under the sink: Perished spout O-rings, loose mounting nuts, split supply hoses, or failed tap tails.
Note when it leaks. Only when hot is on? Only under high flow? With the tap off but other fixtures running (pressure fluctuations)? These clues steer the fix.
Quick Tests: Flow, Drip Rate, And Isolation
- Drip rate: Place a mug under the spout, count drips for 30 seconds, and multiply by two. It helps you confirm improvement after the repair.
- Isolation: Turn off the individual isolation valves under the sink (quarter-turn slotted valves on the supply lines). If not present, close the mains stopcock. If drips continue with the water off, residual water is emptying: if it keeps dripping minutes later, the seat or cartridge is not sealing.
- Aerator check: Unscrew the spout aerator. If the drip stops, debris trapped there is creating a siphon-like effect: clean and refit. If the leak persists, the seal inside the tap is at fault.
Tools And Parts You’ll Need For A Safe Repair
- Adjustable spanner and/or box spanner
- Screwdrivers (flat and Phillips)
- Allen (hex) keys for handle grub screws
- Plumber’s grease (silicone) and PTFE tape
- Replacement washers, O-rings, or the correct cartridge/ceramic disc set
- Seat grinder or reseating tool (if the valve seat is pitted)
- White vinegar/citric acid for limescale, soft brush, microfibre cloth
- Bucket, towels, and a sink plug or cloth to catch small parts
Safety and prep:
- Isolate water at the local valves or mains. Open the tap to release pressure.
- Protect surfaces. Lay a towel in the sink and on the worktop.
- Photograph each stage as you disassemble. It’s a lifesaver on reassembly.
- If your tap is still under warranty, check the terms, some manufacturers will send parts free.
Step-By-Step Fixes For Common Tap Types
Compression Taps: Replacing Washers And O-Rings
- Isolate water and open the tap to drain. Pop the handle cap, undo the screw, and lift off the handle.
- Remove the decorative shroud (hand-tight) to reveal the valve body. Use a spanner to unscrew the valve from the tap.
- Inspect the rubber washer at the valve’s end. If hard, cracked, or grooved, replace like-for-like. A 1/2″ washer suits most basin taps: kitchen taps may be 3/4″, check before buying.
- Replace the spindle O-ring(s) if the handle area was leaking. Grease lightly with silicone grease.
- Check the valve seat inside the tap. If it’s pitted, use a reseating tool to skim it smooth, or fit a seat insert.
- Reassemble. Don’t over-tighten. Turn on water and test.
Pro tip: Don’t crank compression taps off with force: that accelerates washer wear. A firm close is enough.
Cartridge Taps: Swapping Cartridges And Seals
- Isolate water. Remove the handle cap and grub screw: lift the handle. Take off any dome cover to expose the cartridge retaining nut or clip.
- Note hot/cold orientation. Unscrew the retaining nut or pull the clip. Lift out the cartridge.
- Compare the new cartridge, splines and length must match. Some are brand-specific (e.g., 40 mm vs 35 mm, or different spline counts).
- Clean the tap body and inlet filter screens. Remove grit and limescale: rinse well.
- Fit new O-rings/seals supplied with the cartridge. Lightly grease O-rings. Reassemble.
- Turn on water, test both directions. If it drips, double-check the cartridge seating and retaining nut torque.
Ceramic Disc Taps: Cleaning Or Replacing Cartridges
- Access the ceramic cartridge as above (similar to standard cartridge taps).
- If the drip is light and recent, try cleaning: soak the cartridge briefly in vinegar to dissolve limescale, brush gently, and flush. Don’t scratch the ceramic faces.
- Inspect and replace any perished seals. Refit and test. If the drip persists, replace the full cartridge, hairline cracks or worn faces won’t seal under pressure.
Signs it’s ceramic: quarter-turn operation, firm stop, and very smooth motion.
Ball Mixer Taps: Ball Assembly And Seal Kits
- Isolate water. Pry off the handle cap, loosen the handle screw, and remove the handle. Unscrew the dome cap and collar to expose the ball assembly.
- Lift out the cam, packing, and stainless ball. Note orientation.
- Replace the two rubber seats and springs in the body. A generic ball-mixer repair kit usually includes these plus a new ball and cam.
- Inspect and replace O-rings on the spout if there’s a leak at the base. Grease with silicone.
- Reassemble in reverse, ensuring the ball aligns with the ports. Tighten the cap until movement is smooth but not stiff. Test for drips and smooth lever travel.
If The Tap Still Leaks: Troubleshooting And When To Call A Pro
Reseat The Valve: Seat Grinding And Inserts
If you fitted a new washer or cartridge and it still drips, the metal seat inside the tap may be pitted. You’ll see circular grooves or roughness with a torch. Use a reseating tool to lightly grind the seat until smooth and true: clean away swarf thoroughly. Alternatively, fit a seat insert (a small brass ring) to present a new sealing surface. Then refit the valve or cartridge and test.
If the valve won’t budge, apply penetrating oil and use a box spanner to keep the force aligned. Don’t twist against the spout, support it to avoid cracking the body.
Hidden Culprits: Debris, Pressure, And Shut-Off Valves
- Debris and grit: After any plumbing work, tiny particles can lodge in cartridges or discs. Flush the supplies: remove the cartridge, briefly open the isolation valves to blast out grit, then refit.
- Excessive water pressure: UK mains can exceed 5 bar at night. High pressure makes drips worse and destroys seals. If taps hammer or splutter, fit or check a pressure-reducing valve (aim ~3 bar for domestic systems).
- Faulty isolation valves: A weeping isolation valve can mimic a tap leak. Dry everything, wrap tissue around connections, and watch for damp rings.
- Worn tap tails or flexi hoses: Replace if you see bulging, rusted braids, or green staining (verdigris).
Call a pro if: the tap body is cracked, you can’t isolate water, the tap is an integrated boiling/filtered unit, or access is impossible without removing the sink. A good plumber will also match obscure cartridges quickly.
Preventing Future Leaks: Maintenance And Good Habits
Routine Checks, Cleaning, And Lubrication
- Every six months, check under the sink for damp, and feel around connections.
- Unscrew and clean aerators to remove limescale and sediment.
- Add a dot of silicone grease to O-rings during any disassembly. It reduces wear and squeaks.
Manage Water Pressure And Hardness
- Fit a pressure-reducing valve if your pressure is high or variable.
- In hard-water areas, consider a softener or an inline scale reducer on the hot feed to protect cartridges and discs.
- Wipe taps dry after use to slow limescale buildup.
Upgrade Components For Longevity
- Choose branded cartridges and washer kits: cheap rubber hardens quickly.
- If your tap constantly eats washers, reseat the valve or upgrade to a quality ceramic disc mixer.
- Install isolation valves on both feeds if you don’t have them, future repairs become 10-minute jobs.