Table of Contents:
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Introduction
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Common causes of a dripping or stiff tap
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Diagnosing the problem
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Isolating valves and stopcocks
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Repairing a compression (washer-type) tap
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Repairing a cartridge or mixer tap
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How to match a cartridge correctly
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Replacing O-rings and valve seals
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When it’s not the tap at all
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Lubricating a stiff tap
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Freeing stuck nuts and collars without damaging the finish
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Post-repair test checklist
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When to call a plumber
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Conclusion
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FAQ
Introduction
A single drip from a bathroom or kitchen tap might look minor, but it can waste thousands of gallons of water over time. As any seasoned plumber will tell you, a leaking or stiff tap is often an early sign that internal seals have worn out or mineral deposits have built up. In this guide we’ll walk through common causes of leaks and stiffness, diagnostic steps, and step-by-step repair tips for most UK taps and mixer taps. You’ll also find advice on lubricating tight valves, parts you’ll need, and when to call in a professional.
Common causes of a dripping or stiff tap
Tap leaks (drips) and stiffness usually trace back to worn or damaged internal parts. The most frequent culprits are rubber washers, O-rings, valve seats and cartridges. Older compression taps (with separate hot and cold handles) rely on a flat rubber washer to seal off water – if this washer wears, water will seep through. In mixer and modern half-turn taps, tiny O-rings or rubber seals inside the cartridge assembly often leak when they harden or break. Corrosion or lime scale on the valve seat (the metal surface that the washer presses against) can also prevent a perfect seal. Over time these pits and rough edges cause water to dribble even with the tap off. In monobloc (single-lever) taps, a worn ceramic cartridge is a common cause of constant drips – it may crack or clog internally and will usually need replacing. High water pressure or loose tap components (packing nuts, screws) can likewise overwhelm seals and provoke leaks if left unchecked.
- Worn Washer: A flat rubber washer at the base of a tap valve is compressed when the tap is off. If it wears thin or cracks, it won’t seal the flow of water. This is a classic cause of drips at the tap spout.
- Damaged O-ring: O-rings are small rubber seals used on modern taps (especially cartridge or ball taps) around valve stems and spindles. They keep water from leaking around the handle or base. A loose or dried-out O-ring will let water escape, often at the tap handle.
- Corroded Valve Seat: Mineral deposits or corrosion on the metal valve seat (the circular surface inside the tap body) create tiny pits and gaps. Even a new washer cannot seal against a pitted seat, so water drips from the spout. Vinegar cleaning or reseating may fix minor cases, but heavy corrosion often requires part replacement.
- Faulty Cartridge (Mixer Taps): Single-lever mixer taps use a ceramic cartridge that mixes hot/cold flow. If the cartridge is chipped or jammed by debris, it won’t shut off properly, leading to steady drips. Symptoms include leaking from both hot and cold controls or the spout.
- Pressure and Loose Parts: Excessive mains pressure can force water past even good seals. Also, nuts and packing around the tap body can loosen over time. A loose packing nut, for instance, may cause leaks at the base of the tap. Always ensure tap fittings are tight but not over-torqued.
Diagnosing the problem
Before you start dismantling the tap, identify what’s wrong:
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Locate the leak or stiffness: Is water dripping from the spout, from around the handle, or under the sink? If water seeps from the spout but not the handle, it’s likely the valve seat/washer. If it drips at the base or handle, an O-ring is suspect. If the tap handle is hard to turn or creaks, that suggests grime or worn seals inside.
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Check the tap type: Determine whether it’s a compression (old-style two-handle) tap or a cartridge/mixer. A good rule: if the tap handle needs several full turns to open/close, it uses a compression washer; if half a turn (or quarter-turn) gets full flow, it likely has a ceramic cartridge. This tells you what parts to replace.
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Shut off water and test: Isolate the tap by closing its stopcock or the house stopcock. Open the tap to confirm it’s off (no more water) and observe where the drip originates once fully closed.
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Inspect visible components: Remove the aerator (tap spout screen) and check for debris which can restrict flow (though it rarely causes drips). Look under the sink for loose nuts or damp patches. A simple tightening of the nut under the sink can sometimes stop a leak.
Tip: Always plug the sink drain or place a cloth in the basin when working on taps – small screws or springs can fall in!
Isolating valves and stopcocks (what to do if they’re stiff or leaking)
In many UK homes, the hot and cold feeds under the sink have small isolating valves. If yours are the slotted screw type, use a flat screwdriver and turn gently. If they’re lever valves, turn the lever so it sits across the pipe (off).
If an isolating valve won’t move, avoid forcing it. Old valves can snap internally or start leaking around the spindle. In that situation, turn off the main stopcock instead. Once the tap repair is complete, a stiff or weeping isolator is worth replacing, because it’s your easiest way to isolate the tap next time without shutting off the whole house.
Repairing a compression (washer-type) tap
If you’ve determined your tap uses a traditional rubber washer (full-turn handles), follow these steps to replace it:
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Turn off the water. Shut off the isolated supply valve to the tap, or turn the house stopcock off. Open the tap fully and let it drain to relieve pressure. This prevents flooding when you open the tap body.
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Remove the handle. Most taps have a small cap or cover on top of the handle. Pry off this cap with a flat-head screwdriver to reveal a retaining screw. Unscrew it and lift off the handle.
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Unscrew the valve cover (bonnet). Beneath the handle is a valve cover or gland nut. Use your adjustable spanner to loosen this nut. You may need pliers on the tap body (cover with cloth to avoid scratches) to hold it steady. Once loose, unscrew it by hand and lift out the valve assembly (sometimes called the tap spindle).
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Remove the old washer. At the base of the valve spindle you will find the old rubber washer, often held by a small screw. Unscrew that retainer (if present) and remove the washer. Inspect it – typically it will be flattened, cracked or worn.
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Fit the new washer. Match the old washer with a new one of identical size and thickness. Place it on the valve spindle and secure it with the tiny screw (if applicable). Make sure it sits flat without folds.
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Reassemble and test. Replace the valve assembly into the tap, then screw the gland nut and handle back on. Do not overtighten the gland nut – just snug it to avoid future leaks. Turn the water back on and check for drips by turning the tap fully off. If the drip has stopped, the repair is successful.
Repairing a cartridge or mixer tap
Many modern kitchen and bathroom taps are monobloc or half-turn mixers. They use ceramic cartridges instead of simple washers. To fix a leak in these:
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Identify the cartridge. If your tap only needs a quarter-turn or half-turn to go from off to full flow, it has a ceramic cartridge. You’ll replace this entire cartridge.
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Turn off water and remove the handle. Isolate the supply as above, then remove the decorative cap or screw on the handle. Often mixer taps use an Allen key or small screwdriver to detach the handle (check for a hex screw). Lift off the handle.
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Loosen the retaining nut or collar. Under the handle you may see a collar or nut holding the cartridge in place. Use your spanner to loosen this retaining nut. It may be chrome-plated – protect it with a cloth.
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Pull out the cartridge. Once the nut is removed, you can usually pull the ceramic cartridge straight up and out of the tap body. Inspect it carefully. Look for cracks or debris on the ceramic surfaces. If it’s damaged or badly clogged, it must be replaced.
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Fit the new cartridge. Insert the new cartridge in the same orientation (note any tabs or flats on the stem for alignment). Screw the retaining nut back on firmly but not excessively tight.
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Reassemble and test. Put the handle and cap back on. Slowly turn the water on and test the tap in all positions. The new cartridge should stop any drips and restore smooth flow. If leaks persist, double-check that the cartridge is seated correctly and the retaining nut is tight.
Tip: If you don’t have an exact cartridge at hand, you can sometimes buy a universal cartridge set, but matching the old one is easier.
How to match a cartridge correctly (so you don’t waste money)
Cartridges are not one-size-fits-all. Before buying a replacement, remove the old cartridge and check any brand markings or codes. Take clear photos from several angles and measure the diameter if possible. Stem shapes and locating tabs differ between models, and ordering the wrong one is the most common DIY setback.
If you have twin-handle quarter-turn valves, note that hot and cold sides can use different valve units. If one side has failed due to age, replacing both can prevent the other side dripping shortly after.
Replacing O-rings and valve seals
If your diagnosis points to a leaky seal or O-ring (often the case when water drips from around the tap handle or the base of the tap), follow these steps:
- Access the valve or spout. Often the O-ring is inside the valve assembly you remove in the above steps. For example, after lifting out a valve or cartridge, you might see a brittle rubber O-ring seated on the valve stem.
- Remove the old O-ring. Use a small screwdriver to pry off any worn O-ring. Be gentle to avoid scratching metal surfaces. Keep note of its size and thickness.
- Lubricate and install a new O-ring. Lightly coat a matching new O-ring with silicone-based plumber’s grease (this helps it slide into place and prevents tears). Roll it over the stem and into its groove.
- Spout O-rings: If water drips from around the spout, the O-ring under the spout is faulty. Often you need to remove the spout itself. Under the sink there is usually a fixing nut; loosen it with a basin wrench. Then you can twist and lift the spout out to expose the O-ring at its base. Replace and grease this O-ring as above.
- Reassemble. Once new O-rings are in place (and greased), reassemble the tap body and test. A freshly lubricated O-ring should seal completely and allow the handle to turn easily again.
When it’s not the tap at all (flexi hoses, isolators and joints)
Sometimes the tap gets blamed when the real issue is underneath. If you see water pooling in the cupboard, check the flexi hose nuts, isolating valve connections and any compression joints. A slow weep at a hose nut can track along pipework and drip from the lowest point, making it look like the tap is leaking from above.
Dry everything fully, then wrap a dry tissue around each joint to spot the first return of moisture. If a joint leaks, tighten gently. If it continues, the washer/olive may need replacing.
Lubricating a stiff tap
If your tap handle has become stiff or jerky, lubrication and cleaning often solve the problem. Here’s how to proceed:
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Disassemble the tap as described above (turn off water, remove handle and cartridge/valve).
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Clean the internals: Check for mineral deposits or corrosion. Gently wipe the valve seat, stem and seals with white vinegar or a vinegar-soaked cloth. An old toothbrush can help scrub off grit.
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Lubricate all moving parts: Use a high-quality silicone plumber’s grease (not petroleum jelly or WD-40, which can damage rubber). Apply a thin film to all rubber O-rings, seals, and the valve stem where it turns. This creates a protective barrier and restores smooth operation. (Silicone grease is safe on rubber; petroleum grease or mineral oil can cause seals to swell or degrade.)
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Reassemble carefully: Put the tap back together, ensuring seals are seated properly. Avoid over-tightening the handle or nuts – just tighten enough to stop leaks. Turn the water on and the handle should now move freely like new.
Regular lubrication is a good maintenance habit: applying a little silicone grease to tap handles and O-rings every year or two keeps them operating smoothly and prevents seized parts.
Freeing stuck nuts and collars without damaging the finish
Stiff collars and seized nuts are common in older taps and hard water areas. Use the correct size spanner and protect chrome or coated finishes with a cloth. Water-pump pliers can help, but they mark easily if used directly on visible surfaces.
If limescale is the reason the collar won’t budge, wrap a vinegar-soaked cloth around the joint for a short period and try again. Gentle warmth (such as a warm cloth) can help expand metal slightly, but avoid direct flame or harsh heat around plastic components and seals. If the tap body twists while you apply force, stop and stabilise it to avoid stressing the pipework beneath.
Post-repair test checklist (to catch slow leaks early)
After reassembly, restore the water slowly and test methodically. Run the tap for 30–60 seconds to flush any loosened debris, then turn it fully off and watch for drips.
Next, dry the tap body and everything under the sink. Use a dry tissue around hose nuts and joints—tiny weeps show up immediately. Check again after an hour, and once more the next day, as slow leaks sometimes take time to appear.
When to call a plumber
Most leaking taps can be repaired by a confident DIYer, but call a professional if:
- The leak persists despite replacing seals (it could be a cracked valve body or pipe).
- The tap fittings are solidly corroded or snapped (e.g. an old brass tap that won’t come apart). In such cases it may be safer to replace the entire tap.
- You smell gas near a boiler feed tap (rare, but stop work immediately and call an engineer).
- The dripping is coming from the base of a mixer tap and nothing stops it – this could indicate an internal crack.
- The job is simply beyond your comfort level. A plumber can usually replace a troublesome tap or valve in under an hour.
Remember, a little care now avoids bigger problems later. A leaky tap may seem trivial, but even small drips can waste hundreds of litres of water per year. Fixing or maintaining your taps promptly not only saves money but also helps the planet.
Conclusion
Whether it’s a dropped washer, a dried-out O-ring, or a corroded seat, most tap leaks and stiffness can be fixed with basic tools, a new seal, and some plumber’s grease. By diagnosing the symptoms (where it drips, how the handle feels) and following the steps above, you can often restore a tap to smooth, drip-free operation. If in doubt, however, don’t hesitate to seek professional help – a properly fixed tap ensures years of trouble-free use.
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