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TAP & MIXER FAULTS

Tap Keeps Dripping

A dripping tap usually has a worn washer, damaged ceramic cartridge, scored valve seat, failed O-ring or debris preventing the internal valve from sealing.

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Isolate the hot and cold supplies before dismantling a tap

Use local service valves or the main stopcock. Do not force seized valves or tap handles. Keep water away from sockets and appliances, and stop if a cracked tap body, failed flexi hose or uncontrolled leak is present.

MOST LIKELY CAUSES

Start with these

Worn washer Traditional taps rely on a rubber washer sealing against a seat.
Failed ceramic cartridge Quarter-turn taps use ceramic discs that can wear or crack.
Damaged valve seat Pitting and scale can prevent a new washer sealing.
Debris or limescale Small particles can hold the valve slightly open.
◫ Symptom variations Match the exact tap behaviour before repair. ⌄
  • Drip continues when tap is fully closed
  • Drip gets worse over time
  • Tap needs extra force to stop
  • Only hot or cold side drips
  • Drip returns after washer replacement
✓ Quick checks Simple checks before removing tap parts. ⌄
  1. Identify whether the fault affects hot, cold or both supplies.
  2. Dry the tap and surrounding area to trace leaks accurately.
  3. Check local isolation valves, flexible tails and visible connections.
  4. Remove and inspect the aerator where flow is poor.
  5. Do not force stiff handles, valves or seized fittings.
If the cause is found: keep the affected supply isolated until the correct repair is completed.
If the leak cannot be controlled: close the main stopcock and call a plumber.
1 Step 1 — Isolate the tap supplies Isolate water supplies before dismantling tap components. ⌄

Process

Close the local service valves or main stopcock and open the tap to relieve pressure.

Success looks like: The tap is safe to dismantle.
Escalate when: If isolation valves leak or will not close, stop.
2 Step 2 — Identify the valve type Isolate water supplies before dismantling tap components. ⌄

Process

Check whether the tap uses a traditional washer or ceramic cartridge.

Success looks like: The correct replacement part is selected.
Escalate when: Do not force mismatched parts.
3 Step 3 — Replace the failed sealing component Isolate water supplies before dismantling tap components. ⌄

Process

Fit the correct washer, cartridge or O-ring and reassemble carefully.

Success looks like: The tap shuts off cleanly.
Escalate when: If dripping remains, the valve seat or body may be damaged.
⌁ Common causes explained Why taps drip, seize, leak or lose flow. ⌄

A dripping tap usually has a worn washer, damaged ceramic cartridge, scored valve seat, failed O-ring or debris preventing the internal valve from sealing.

Tap faults often come from small internal seals, cartridges, washers and local restrictions. Water can also track down the tap body and appear under the sink away from the true source.

⌘ Advanced diagnostics Plumber-level checks and repair work. ⌄
  • Inspect and reseat traditional valve seats where suitable.
  • Replace ceramic cartridges with matching spline and dimensions.
  • Check body O-rings and seals.
  • Flush debris before reassembly.
  • Test hot and cold sides under full pressure.
▣ Parts that may need replacing Common components linked to this fault. ⌄
  • Tap washer
  • Ceramic cartridge
  • O-ring set
  • Valve headgear
  • Tap reseating component
! When to call a plumber Conditions that should end basic troubleshooting. ⌄
  • The local isolation valves will not close or are leaking.
  • A flexible hose is bulging, split or corroded.
  • The tap body or pipe connection is cracked.
  • The tap is heavily corroded or inaccessible.
  • A thermostatic or pressure-balance fault creates a scalding risk.
  • The leak or poor flow remains after basic service work.
? Frequently asked questions Common questions about tap faults. ⌄

How do I know whether the tap uses a washer or ceramic cartridge?

Traditional screw-down taps usually use washers. Quarter-turn and many lever taps use ceramic cartridges.

Can I replace a cartridge with any similar-looking one?

No. Height, diameter, spline count and inlet layout must match.

Why is only one side of a mixer tap weak?

That side may have a partly closed valve, blocked hose, inlet filter or cartridge passage.