Why London’s leak detection specialists are busier than ever this autumn

London leak detection firms are reporting a sharp rise in calls this autumn, driven less by dramatic burst pipes than by something harder to see: slow, hidden leaks that have been building for months.

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London Leak Specialist, which carries out leak investigations across all 33 London boroughs, says demand for its leak detection service has risen 35% compared with the same period last year. Search interest points the same way: around 4,400 people a month in the UK search for “water leak detection”, and another 1,680 for “trace and access”, the term for opening a wall or floor only at the point needed to reach a leak.

The leaks people cannot find

What stands out in the firm’s records is how many customers had already tried to solve the problem themselves. One homeowner had a surveyor confirm the damp was not salt related, which ruled out water coming in from outside, but the surveyor could not say where it came from. Another had an appliance engineer confirm their washer dryer was working properly and suspect a pipe joint inside the wall. Roughly half of the firm’s recent jobs involved damp or mould where the source was unknown.

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High meter readings are another pattern. In one case a household’s meter was running at about 60 litres an hour, which is roughly 1,440 litres a day, and three water company engineers had visited and found nothing wrong with the meter or the pipework. The fault sat on the private side of the supply, which is where a water company’s responsibility ends.

Heating systems account for a large share too. Around a third of recent jobs began with a boiler or central heating system that kept losing pressure after being topped up. Leaks in pipework under screed or concrete floors can run for weeks before a damp patch appears at the surface.

Close to half involved water coming through a ceiling from a neighbour, and with it a dispute. The upstairs resident believes their plumbing is fine, the downstairs resident can see the stain. A written report that names the source is often what settles who has to pay.

Why now

Heating comes back on after months idle, so joints and seals that held when unpressurised are tested again. Cold snaps move pipes. Insurers also ask claimants for evidence, and a leak report is increasingly requested before repair work starts.

The burst water main at Molesey on 28 September, which cut supply to thousands of homes in south west London, put water infrastructure back in the news. That was a failure on the supplier’s network. Most of what specialists see is on the customer’s side of the boundary, where responsibility, and the bill, usually belong to the owner.

What leak detection costs

London Leak Specialist publishes its rates: £160 an hour for standard leak detection, with most homes found in two to four hours, so a typical visit lands between £320 and £640. Tracer gas, which is pumped into a pipe and detected where it escapes, adds £80 for the bottle. Central heating and underfloor heating traces are charged at £200 an hour, typically £400 to £800 in total. Prices vary between firms, so ask any provider for a written estimate and whether they charge if nothing is found.

London Leak Specialist: published leak detection prices

How specialists find a leak without wrecking the house

Water travels along joists and behind plaster, so the stain is often metres from the fault. Specialists combine acoustic listening, thermal imaging, moisture mapping and tracer gas, so walls and floors are opened only at the exact point. That precision matters for tenants, landlords and anyone who has paid for a surveyor and still has damp.

Barnet: who is responsible?

A leak on the public main, up to your boundary or stopcock, is the water company’s job. Barnet is served by more than one supplier, including Thames Water and Affinity Water depending on the street, so check your bill to see which one is yours. The private supply pipe from the boundary to your home, and all pipework, tanks and heating inside it, normally belong to the owner, or the landlord if you rent. A leak from the flat above depends on the lease and the cause, and often starts with a written report identifying the source.

Affinity Water: reporting and dealing with leaks

London Leak Specialist says it is also very active across Barnet, from Finchley, Hendon and Edgware to Barnet town and New Southgate. In New Southgate, N11, a hidden washing machine valve leak was behind a wet plug socket in a kitchen. The borough’s mix of 1930s semis, converted flats and post war blocks means the same three problems keep turning up: hidden pipework under floors, leaks between flats and heating systems losing pressure.

London Leak Specialist: leak detection in Finchley and Barnet

Case study: a hidden washing machine valve leak in New Southgate, N11

What to do if you suspect a leak

Turn off every tap and appliance and check your water meter. If it is still moving, water is escaping somewhere. Look for damp patches, bubbling paint, warped skirting boards or a musty smell, especially below bathrooms and kitchens, and photograph the damage with dates for your insurer.

Then read your insurance policy. Many policies cover tracing and access, but not all, and some exclude gradual deterioration, so check the wording or ask your insurer before work starts. Book a detection visit before any plaster is touched, and ask what method will be used and what the written report will contain.

London Leak Specialist: leak detection and insurance claims

Disclosure: London Leak Specialist is operated by a business connected to the owner of Barnet Press.