Leak Detection & Repair in North West London

How can you tell if you have a hidden leak?

The water meter tells you fastest. Turn off every tap and make sure the washing machine and dishwasher are not filling. Read the meter, wait 15 minutes without using water, and read it again. Affinity Water, which supplies most of our area, says that if the two readings differ you may have a leak.

Then close the internal stopcock and repeat. If the meter stops, the leak is inside the property. If it keeps turning, the leak is outside, between the meter and the stopcock, on the supply pipe. Without a meter, look for the signs instead.

• A stain or bulge on a ceiling, or a damp patch on a wall that keeps growing
• Water trickling down the back of the toilet pan when nobody has flushed
• A combi boiler whose pressure gauge keeps falling, which points to the heating system
• A floor that feels soft or cold and damp, or a musty smell from a cupboard
• A lush strip of lawn or a wet path in dry weather, which points to the supply pipe
• A water bill that has jumped with no change in how you use water

How we trace a leak without a thermal camera

Most leaks give themselves away to methodical testing. First we split the plumbing into systems: the mains cold supply, the hot water and the central heating. Closing valves and capping sections lets us pressure-test each part on its own with a test pump and gauge. The section that loses pressure is the one leaking, and the rest can be ruled out. Timing is the next clue. A leak that runs day and night is on a pressurised pipe. One that appears only when the shower runs is a waste, a tray seal or the grout and silicone around it, and we flood test those directly.

A stain that only grows after heavy rain is probably not plumbing at all. Moisture readings across the ceiling, wall or floor then find the wettest point, which is usually close to the source. Only when the results agree do we open up, by a tile or a board rather than a whole room.

When a specialist leak survey is the better route

Some leaks cannot be pinned down by isolation and pressure tests without opening a large area. Then a specialist with thermal imaging, acoustic listening or tracer gas can usually locate the fault without lifting anything. We tell you when that is the better spend, and make the repair once the point is marked.

• Pipes buried in a concrete floor or screed, common in ground-floor flats and extensions
• Underfloor heating, where opening the floor to look would damage the system
• A long supply pipe under a drive or garden where digging blind would be expensive
• Expensive finishes such as stone floors or fitted kitchens over the suspect area
• An insurer that asks for a formal trace and access report before work starts

A ceiling leak: what the stain tells you

Where the stain sits and when it grows narrows the cause before anyone climbs a ladder. Under a bathroom, the usual culprits are a failed shower tray or bath seal, tired grout, a leaking waste, or a toilet pan connector. Under a kitchen, it is often a dishwasher or washing machine hose. A stain that spreads all the time, even overnight, points to a pressurised supply or heating pipe. If a ceiling is sagging or bulging with water, keep people out from under it and switch off the lighting circuit for that room at the consumer unit.

Then turn off the water. If the leak is coming from a flat above, your own stopcock will not stop it, and you need the upstairs occupier or the managing agent. We can trace the source once there is access, and put in writing whose pipe or seal failed.

A leak under the sink

Leaks under a kitchen or bathroom sink are usually quick to find and fix, and the trick is to dry everything first. Wipe the pipes, put kitchen roll on the cupboard floor, then run the cold tap, then the hot, then fill the sink and let it drain. The first wet spot shows you which part has failed.

• Drips while taps run: the tap connectors or the joints on the tap tails
• Drips only when the sink drains: the waste, the trap washers or the plug seal
• Water under the unit with the sink unused: the dishwasher or washing machine hose, or its valve
• Wet along the worktop edge: the seal between the sink and the worktop, not a pipe

A leak on the supply pipe: who is responsible?

The owner of the property is responsible for the supply pipe, which runs from the boundary stop tap into the house, along with all the plumbing inside. Affinity Water owns the mains and the communication pipe up to the boundary stop tap. Where a supply pipe is shared with neighbours, everyone beyond the leak shares the repair, wherever the leak is. In a rented home the landlord arranges it, because section 11 of the Landlord and Tenant Act 1985 puts the water installations in the landlord's repairing duty. Affinity may repair a household supply pipe leak free of charge under its Leak Repair Scheme.

It can only work up to the boundary, not near or under buildings or in hard-to-reach gardens, and it does not offer 24-hour emergency help. For metered households, a leakage allowance on the bill may be available once the leak is fixed, usually on a first claim and a repair within a month. If a leak is left, Section 75 of the Water Industry Act 1991 lets a water company serve notice requiring the repair, with at least seven days to comply.

Insurance and trace and access cover

Many buildings insurance policies include trace and access cover. It pays to find a hidden leak and to open up and make good the area around it, though usually not to repair the leaking pipe itself. Limits and conditions vary a lot. Some policies only pay trace and access as part of a wider damage claim, and some insurers want to be told, or to send their own contractor, before any floor is lifted.

Ring your insurer before we open anything. Our written note sets out the tests, the readings, where the leak was and what failed, with photographs before and after, which is what a claim handler asks for. In a block of flats, the freeholder's buildings policy may be the one that responds.

What decides the cost of finding a leak?

Finding the leak is usually most of the time; the repair is often quick. Diagnosis is charged by the hour, and the time depends on how many systems need testing, how easy the valves are to reach and how far the water has travelled. A dripping trap takes minutes to confirm. A slow leak feeding a ceiling two rooms away takes longer, because each section is tested in turn.

The second variable is opening up and making good. Lifting a floorboard is quick. Cutting out tiles or plasterboard means replacing or redecorating afterwards, and we tell you before we start what has to come up.

Certificates and defined jobs are a fixed price confirmed before we attend; repairs are charged by the hour, with the rate and an estimate confirmed before we attend.

Where we trace leaks

We cover Harrow, Kenton, Stanmore and Edgware, and across North West London to Wembley, Kingsbury, Pinner, Mill Hill, Hendon, Colindale, Northwood, Ruislip and Bushey. The housing here shapes the leaks. Interwar semis usually have suspended timber ground floors, which makes pipes under them easy to reach by lifting a board. Flats and extensions often have pipes in solid floors, which is where a specialist survey earns its fee.

Plumbing by area: Plumbers in Harrow, Plumbers in Kenton, Plumbers in Stanmore, Plumbers in Edgware, Plumbers in Bushey, Plumbers in Colindale, Plumbers in Hendon, Plumbers in Mill Hill, Plumbers in Northolt, Plumbers in Northwood, Plumbers in Pinner, Plumbers in Ruislip and Plumbers in Wembley.

What we will not do

We do not carry thermal imaging, acoustic or tracer gas equipment, and we will not pretend a moisture meter is a leak survey. We do not investigate damp: if a wall stays wet once the leak is fixed, or the cause looks like rising damp or condensation, that needs a damp specialist. We do not repair boilers, so a boiler leaking internally needs a Gas Safe registered engineer. Roof and gutter leaks go to a roofer, and we do not carry out CCTV drain surveys.

Why people trust us

• Repairs tested before we leave, and the area left clean
• A walk-in office on Kenton Lane, not a serviced address
• We diagnose first and tell you what we have found before doing more
• A time slot rather than a morning-or-afternoon window
• Work photographed before and after, and reported
• We tell you when you do not need something we sell

We are building a review profile under this name and would rather show you none than borrow someone else's. Ask us for references from landlords and we will put you in touch.

Official sources

• Affinity Water: Leaks, checking for a leak and who should repair it
• Affinity Water: Leakage information, who is responsible for which pipe
• Drinking Water Inspectorate: lead in drinking water (supply pipe responsibility)
• legislation.gov.uk: Water Industry Act 1991, section 75
• legislation.gov.uk: Landlord and Tenant Act 1985, section 11

Last reviewed October 2026 by EliteShires Property Services.