Leaking Tap Repair Guide for Cobham Homeowners

Published July 2026 | Leaking Tap Repair

This guide covers how to diagnose and repair the most common types of leaking tap, from worn washers to failing ceramic disc cartridges. It's written for homeowners in Cobham and the wider Surrey area who want to have a go at fixing it themselves before calling a plumber out.

Before You Start - Safety First

A dripping tap might look like a minor inconvenience, but left alone it can waste thousands of litres of water a year and add real money to your bills. Before you touch anything under a sink or inside a tap, you need to know where your main stopcock is.

Your stopcock is typically found under the kitchen sink, in a cupboard near the front door, or in the airing cupboard. Turn it clockwise to shut off the water supply to the whole property. If you can't locate it, check with your neighbours - in many Cobham terraces and semi-detached houses built in the 1960s and 1970s, the stopcock is near the front boundary or in a shared access point outside.

Before you start work, run through this checklist:

• Turn off the water supply completely before dismantling anything
• Open the dripping tap after shutting off the supply to drain residual pressure from the pipe
• Put a towel or bowl under the work area to catch any water still in the pipes
• Never force a fitting that won't budge - seized fittings can crack if you rush them

What You Will Need

Our engineers see a lot of jobs stall halfway through because the homeowner is missing one small part. Get everything together before you start - you don't want to be running to the merchant with the water still off.

Tools

• Adjustable spanner (200-250mm)
• Flat-head and cross-head screwdrivers
• Slip-joint pliers or grips
• Allen keys (for modern lever-handle taps)
• Small flat-head screwdriver for removing decorative caps

Materials

• Tap washer assortment kit (kits available from Screwfix, B&Q, or a local plumbers' merchant for around 3 to 5 pounds)
• O-ring set
• PTFE tape
• Plumber's grease
• Tap reseating tool - optional, roughly 15 to 25 pounds, only needed if the tap seat itself is worn

Time Estimate

A washer replacement on a traditional pillar tap typically takes 30 to 60 minutes. A ceramic disc cartridge replacement on a modern mixer tap can take 45 to 90 minutes if you haven't done it before. If you run into corroded fittings or awkward access under a kitchen unit, allow two hours and don't rush.

Step-by-Step Instructions

The exact process varies depending on whether you have a traditional pillar tap (separate hot and cold, older style) or a modern mixer tap with a quarter-turn action. The steps below cover both types - we'll flag where the approach diverges.

Step 1 - Shut Off the Water and Drain the Tap

Turn off the stopcock or the isolation valve under the sink. Then open the leaking tap fully to drain any water sitting in the supply pipe - this releases residual pressure and stops water dripping while you work. Don't skip this step. Working on a live pressurised pipe is how you end up soaking the kitchen floor and the cupboard underneath.

Step 2 - Remove the Tap Handle

Most tap handles are secured by a small screw hidden under a decorative cap on top. Use a small flat-head screwdriver to pop the cap off - it's usually a red or blue indicator disc. Undo the screw underneath, then lift or pull the handle free. If it's stuck, twist gently while pulling upward. Take your time - don't yank it.

Step 3 - Access the Headgear or Cartridge

With the handle off, you'll see the headgear - the internal working part of the tap. On a traditional pillar tap, this is a brass or chrome hexagonal nut. Use your adjustable spanner to undo it anti-clockwise. Wrap the spanner jaws with tape to avoid scratching the chrome finish. On a modern mixer tap, you'll typically see a cartridge that lifts or pulls out once the retaining clip or nut is removed.

Step 4 - Inspect and Replace the Washer

On a traditional tap, the washer sits at the bottom of the headgear and is held by a small brass nut. Undo the nut, remove the worn washer, and compare it against your replacements. The most common sizes in UK homes are 12mm and 3/4 inch. Fit the new washer, tighten the nut firmly - not aggressively - and you're ready to reassemble. If the washer looks fine but has visible grooves pressed into it, the tap seat is likely worn and that's what you need to address instead.

Step 5 - Check and Replace the O-rings

If the leak is coming from the base of the spout rather than the nozzle, the washer isn't the problem - it's a worn O-ring. O-rings are the rubber sealing rings that sit around the body of the tap. You'll need to remove the spout itself (it usually twists off once the handle is out of the way) to get to them. Roll the old O-ring off, apply a small amount of plumber's grease to the new one, and roll it on carefully. This is one of the most common faults our engineers see on kitchen mixer taps across Surrey, particularly on taps that are 10 years old or more.

Step 6 - Replace a Ceramic Disc Cartridge (Modern Taps)

If you have a modern mixer tap with a quarter-turn lever action, it uses a ceramic disc cartridge instead of a washer. These cartridges crack, warp, or get clogged with limescale over time. Once you've removed the handle and the retaining nut or clip, the cartridge should pull straight out. Take it to your local plumbers' merchant in Cobham or look up the exact replacement online - the brand name is often printed directly on the cartridge. Brands like Grohe, Bristan, and Hansgrohe all have widely available replacement cartridges. Fit the new one in the same orientation as the old one, reassemble, and test before putting tools away.

Step 7 - Reassemble the Tap

Work back in reverse order. Refit the headgear or cartridge, tighten the retaining nut, refit the handle, and press the decorative cap back into place. If you're reassembling any threaded fittings, wrap two or three turns of PTFE tape around the threads before fitting to help create a good seal. Don't overtighten the headgear nut - firm is enough, over-tightening can crack the tap body on older chrome taps.

Step 8 - Turn the Water Back On and Test

Turn the stopcock back on slowly. Let water run through the tap briefly to flush out any debris that's been sitting in the pipe, then close it off and watch for two or three minutes. Check the spout, the base of the tap, and the pipework connections underneath. No drip means the job's done. If it's still leaking, move on to the next section.

What to Do If This Does Not Fix It

A new washer or cartridge that doesn't solve the drip usually points to one of three underlying issues.

The most common cause is a worn tap seat. The seat is the machined metal surface inside the tap body that the washer presses against to seal. If it's pitted, corroded, or ridged from years of use, no washer will seal against it properly. You can check it by running your finger over the surface - it should feel smooth. A tap reseating tool can resurface it at home, but it takes practice to use correctly and the results vary.

If you've run a check through the Voltrade GoFIX diagnostic tool and it's flagged a cartridge fault, but fitting a replacement hasn't stopped the drip, the issue may be with the water pressure feeding the tap. High mains pressure is a known issue in parts of Surrey and can shorten the life of internal tap components significantly - particularly ceramic discs, which are more pressure-sensitive than traditional washers.

Limescale is another common culprit, particularly in Cobham where the water supply is moderately hard. Heavy scale deposits inside the cartridge housing or on the washer seat stop components seating correctly. Soaking parts in white vinegar for a few hours will dissolve most limescale. If you can see visible scale build-up inside the tap body, clear that before fitting new components.

When to Stop and Call a Professional

Some situations call for a plumber rather than a DIY fix. Knowing when to stop can save you from turning a small repair into a bigger, more expensive one.

• Corroded or seized fittings. If the headgear nut won't turn or the spindle is corroded solid, forcing it risks cracking the tap body or damaging the supply pipe. A plumber will have the correct tools and the experience to know when replacement is safer than repair.
• Lead pipework. Some older properties in Cobham, particularly those built before the late 1960s, may still have original lead supply pipes. Lead pipe is grey, soft, and scratches easily with a fingernail. If you suspect lead pipework, don't disturb it - contact a WaterSafe-registered plumber.
• Leaks at the pipe fittings, not the tap. If water is coming from the compression or push-fit fittings under the sink, that's a separate job from the tap itself. It may need soldering or specialist fitting tools.
• The same tap keeps leaking repeatedly. If you're replacing washers every few months on the same tap, the root cause is usually high mains pressure, an incompatible replacement part, or a failing tap body. A plumber can diagnose and fix the underlying problem rather than just patching the symptom.
• You're not confident. That's a perfectly reasonable reason to call someone. A leaking tap repair carried out by a local plumber in the Cobham area will typically cost between 80 and 150 pounds for a standard washer job, or 120 to 200 pounds for a cartridge replacement or tap reseating. That's nearly always less than the cost of fixing water damage from a repair that's gone wrong.

Questions About This Process

How much does it cost to have a leaking tap repaired by a plumber in Cobham?

Most plumbers in Cobham and the surrounding Surrey area charge a callout fee of 50 to 80 pounds, with labour and parts on top. A basic washer replacement typically comes to 80 to 130 pounds all in. A ceramic cartridge replacement or a job involving tap reseating usually costs between 130 and 200 pounds. Always ask for a fixed quote before work starts rather than agreeing to an open-ended hourly rate - most straightforward tap repairs are well within a fixed-price callout.

How do I know whether to repair my tap or replace it entirely?

If the tap body is cracked, heavily corroded, or the internal threads are stripped, a repair won't hold long-term and a full replacement makes more sense. Replacement kitchen taps start from around 30 to 50 pounds for a budget option and can run to several hundred for a premium brand. If the tap is less than 10 years old and the body is in good condition, a washer or cartridge replacement will almost always solve the problem at a fraction of the cost. If you're unsure, a plumber can give you a quick assessment before you commit to either option.

Can a dripping tap cause damage to my home?

Yes - and more quickly than most homeowners expect. A tap dripping at roughly one drop per second can waste around 5,500 litres of water per year. Beyond the water bill, persistent moisture under a sink leads to mould growth, rotting cabinet bases, and damage to the floor or wall behind the unit. In properties with older pipework, a dripping tap can also indicate that fittings elsewhere in the system are under stress. Fixing it promptly is always the right call.