How to Fix a Leaking Tap in London

Published August 2026 | Leaking Tap Repair Guide

This guide covers how to diagnose and repair a dripping or leaking tap in your home, from identifying the type of tap you have through to fitting the correct replacement parts. It's written for confident DIYers who are comfortable with basic plumbing tasks, and for anyone who wants to understand what's involved before deciding whether to call a plumber.

Before You Start - Safety First

Before you touch any tap, you need to isolate the water supply. Our engineers see a surprising number of jobs in London where someone has attempted a tap repair without doing this first, ending up with water spraying across the kitchen or bathroom. Don't make that mistake.

Start by locating your stopcock - the main water shut-off valve for your home. In most London properties, this is found under the kitchen sink, in a utility room, or near the front door in an internal cupboard. Turn it clockwise until it stops moving. Then open the tap you're repairing to release any remaining pressure in the pipes and allow residual water to drain out.

If you can't locate your internal stopcock, or it's seized and won't turn, stop here. You'll need to turn off the supply at the external stop tap in the pavement outside your property, which requires a special key. Thames Water, which covers most of Greater London, can advise on how to access this if needed.

A few more points before you start:

• Work in good lighting. Getting into awkward positions under a sink in the dark is how accidents happen.
• Place a towel or bowl under the tap to catch residual water in the pipes.
• Take photos before you disassemble anything. This pays off when you're trying to put it all back together.
• If there are electrical sockets near the tap - under-counter outlets, for example - switch those off at the fuse box before you begin.

What You Will Need

Most tap repairs don't require specialist tools, but having the right kit before you start will save you a frustrating mid-job trip to the hardware shop.

Tools

• Adjustable spanner or basin wrench
• Flat-head and cross-head screwdrivers
• Needle-nose pliers
• PTFE tape (plumber's tape)
• A cloth or old towel
• A small bowl or bucket

Materials

• Replacement tap washer (commonly 1/2 inch or 3/4 inch - check your tap type before buying)
• O-rings, if you have a mixer tap or cartridge-style tap
• Replacement ceramic disc cartridge, if needed for your tap model
• Plumber's grease

Parts are inexpensive. A pack of assorted tap washers typically costs between 3 and 8 pounds. O-rings are similarly cheap - a full assorted pack from a plumber's merchant or DIY store usually runs around 5 to 10 pounds. If you need a ceramic disc cartridge, expect to pay between 10 and 25 pounds depending on the brand and size. For branded mixer taps from manufacturers such as Grohe, Hansgrohe, or Bristan, you may need to order parts directly from the manufacturer or a specialist supplier rather than picking up a generic "compatible" part from a general DIY store.

Time Estimate

For a standard compression tap washer replacement, allow 30 to 60 minutes if you're doing it for the first time. Cartridge replacements on modern mixer taps can typically be completed in around 20 minutes once you've identified and sourced the correct part. Sourcing the right part can sometimes take longer than the repair itself - factor in delivery time if you're ordering online.

Step-by-Step Instructions

The repair process varies depending on the type of tap you have. The two most common types found in London homes are compression taps - traditional separate hot and cold taps with a visible spindle - and cartridge or ceramic disc mixer taps, which are the single-lever or twin-handled modern style. The steps below cover both.

Step 1 - Isolate the water supply and open the tap

Turn off the water at the stopcock by turning it clockwise until it stops. Open the tap fully to release any pressure remaining in the supply pipe and let the residual water drain out. Keep a towel under the tap throughout this process.

Step 2 - Remove the tap handle

Look for a decorative cover or cap on top of the tap handle - it typically pops off with a flat-head screwdriver. Underneath you'll find a screw, usually Phillips or flat-head, holding the handle in place. Unscrew it and lift the handle off. Some handles are stiff from years of limescale or general age. A gentle twist while pulling upwards usually loosens them. Avoid forcing it with excessive pressure or you risk cracking the tap body.

Step 3 - Remove the packing nut

On a compression tap, you'll now see the packing nut (also called the gland nut) surrounding the spindle. Use your adjustable spanner to unscrew it anti-clockwise. Take care not to round off the nut - if it's corroded, apply a small amount of penetrating oil and leave it for a few minutes before trying again. On cartridge taps, you may see a retaining clip or collar at this stage rather than a threaded nut.

Step 4 - Remove the headgear and access the washer or cartridge

Once the packing nut is off, unscrew the headgear - the main body of the tap mechanism - by turning it anti-clockwise. At the base of the headgear you'll find the tap washer, held in place by a small brass nut. Undo the nut with pliers, remove the old washer, and compare it carefully to your replacement options. For cartridge taps, you'll pull the whole cartridge assembly out rather than just a washer.

Step 5 - Fit the replacement washer or cartridge

Fit the new washer and tighten the retaining nut. While you're in here, check the O-rings on the spindle and around the headgear. If they look cracked, flattened, or perished, replace them now - it's a small extra cost but avoids you having to come back in here again soon. Apply a thin layer of plumber's grease to new O-rings before fitting them to help create a proper seal. For cartridge taps, note the orientation of the old cartridge before you remove it, then fit the new one the same way.

Step 6 - Reassemble the tap

Screw the headgear back in clockwise, then refit the packing nut and tighten it firmly. Don't overtighten - you're working with brass fittings, and too much force can crack them or distort the new washer. Reattach the handle, replace the retaining screw, and clip or press the decorative cover cap back on.

Step 7 - Restore the water supply and test

Turn the stopcock back on slowly (anti-clockwise) and let the pressure build gradually. With the tap closed, check around the base and spindle for any signs of dripping from the tap body. Then open the tap fully, let it run for a few seconds, and close it again. Watch for at least 60 seconds. If the drip has stopped, the job's done. If it hasn't, move on to the section below.

What to Do If This Does Not Fix It

If the tap is still dripping after a washer replacement, there are a few common explanations worth working through before calling a plumber.

The tap seat may be damaged. The seat is the metal surface inside the tap body that the washer presses against to form the seal. Over time - particularly in parts of Greater London with hard water - limescale and corrosion can pit or roughen this surface. A new washer won't seal properly against a damaged seat no matter how perfectly it fits. You can buy a tap seat reseating tool for around 15 to 30 pounds and resurface the seat yourself, but this takes practice. Alternatively, a plumber can do it quickly with the right equipment.

You may have the wrong size washer. It sounds obvious, but it's one of the most common reasons a repair fails. If the washer is even slightly too small or too large, you won't get a watertight seal. Double-check the size against the retaining nut and try again with a correctly sized replacement.

The cartridge may be incorrect for your tap model. If you have a ceramic disc mixer and replaced the cartridge but still have a drip, check that you've fitted the exact right part. Our engineers regularly find that homeowners have ordered a "compatible" cartridge that doesn't quite match the tap's internal dimensions. For Grohe, Hansgrohe, or Bristan taps in particular, using a genuine manufacturer part is almost always worth the premium.

If you're not sure whether the problem is the tap itself or something further back in your plumbing system, Voltrade's GoFIX diagnostic tool can help you work through what's causing the symptom before you commit to a more involved repair.

When to Stop and Call a Professional

Some tap repairs are well within reach for a capable DIYer. But there are situations where calling a qualified plumber in London is simply the right decision.

• You can't isolate the water supply. If your internal stopcock is seized or you can't locate it, don't attempt the repair. A plumber can also address a stuck stopcock as part of the job.
• The tap body is cracked or heavily corroded. If the tap itself is structurally compromised, it needs replacing entirely. Attempting to repair a cracked tap body risks the situation deteriorating rapidly.
• The pipes near the tap look corroded or in poor condition. In older properties - particularly the Victorian and Edwardian housing stock found across Greater London - you may encounter lead pipework or badly corroded copper. This requires a professional assessment before any repair work proceeds.
• The leak is at a pipe joint or fitting, not the tap spout. Compression fittings, push-fit connections, and soldered joints are a different category of repair entirely.
• You've attempted the repair twice and it hasn't worked. At that point, the problem is likely more complex than a simple washer or cartridge swap, and the diagnosis needs to change.

A typical call-out and labour charge for a plumber in London is commonly between 80 and 150 pounds per hour, with most plumbers charging a minimum call-out period of one hour. A tap repair or full tap replacement is typically completed within that time. If you need a new tap supplied and fitted, budget for around 150 to 300 pounds depending on the tap specification, brand, and how accessible the pipework is. Our engineers cover all of Greater London, so if the DIY route isn't working, getting a professional on-site quickly is usually the faster and more cost-effective long-term option.

Questions About This Process

How do I know what type of tap I have?

The quickest way to tell is by looking at how the tap operates. If you have two separate taps that you turn clockwise to close, these are almost certainly compression taps with traditional washers. If you have a single lever or a modern twin-handle tap where turning produces a smooth, even action, it's likely a cartridge or ceramic disc tap. If you're still not sure, removing the handle will reveal the mechanism clearly - you'll either see a spindle with a washer at the base, or a cylindrical cartridge assembly.

Why does my tap keep dripping even after I replaced the washer?

The most common cause is a damaged tap seat - the metal surface inside the tap body that the washer seals against. In London's hard water areas, limescale and corrosion can roughen or pit this surface over time, meaning even a correctly sized new washer won't create a watertight seal. The seat can be resurfaced using a tap reseating tool, or the tap may need replacing. If you've changed the washer twice with no result, it's worth having a plumber inspect the seat before spending more on parts.

Can a dripping tap noticeably increase my water bill?

Yes, and more than most people expect. A tap dripping at roughly once per second can waste thousands of litres of water over the course of a year. Thames Water charges for both water supply and sewerage based on consumption, so a persistent drip adds to both elements of your bill. Beyond the cost, unnecessary water waste puts extra demand on the local supply network. Fixing a dripping tap is one of the most cost-effective home maintenance tasks available to any homeowner.