Emergency Leak Detection in London: How a Visit Works

What emergency leak detection actually is

A leak is an emergency when water is escaping now and you cannot contain it, or when it is reaching something that matters: electrics, a ceiling that is holding water, a neighbour below, a meter that will not stop turning. Emergency leak detection is the service for that situation. An engineer comes to the property, works out where the water is coming from, and stops it. The finding is the product. A stained ceiling tells you that water is somewhere above it. It does not tell you where the pipe is, which joint has failed, or whether the water is from the mains, the hot circuit, a waste or the heating.

Most people who ring about a leak have already guessed at the source. Often the guess is wrong, and that is not a criticism. Water runs along joists, pipes and the back of plasterboard before it shows itself, so the wet patch is frequently a metre or more from the fault. Detection is the job of replacing the guess with evidence: a reading, a recording, an image, a pressure trace that behaves in a way only one fault could cause.

We work on water leaks only, across all of London, and the service is available 24/7, including nights, weekends and bank holidays. Gas, boiler faults and electrical faults are other trades, and a gas smell comes before everything on this page: leave the building and ring the National Gas Emergency Service.

Is it an emergency, or can it wait until morning?

Some leaks need an engineer tonight and some are better handled in daylight with the water off. The honest triage is below. If you are unsure, the can a water leak wait until morning guide goes through the night-time decision in more detail, and the burst pipe guide covers the most common alarming case.

The table is a guide, not a diagnosis. Anything that sits between two rows, or that you cannot see properly in the dark, should be treated as the more urgent row until someone has looked.

• If the water is near electrics, treat it as an emergency whatever its volume.
• If you can stop the flow at a stop tap and the property is then dry and safe, most leaks can wait until daylight.
• If the water is reaching a neighbour, treat it as an emergency, because the damage is no longer only yours.

What happens on an emergency leak detection visit

The sequence below is how a visit normally runs. The order can change when a situation demands it, for instance when the first priority is stopping water that is pouring through a ceiling. The detailed customer-side version, from the first call to the written findings, is on the how it works page.

• Booking: you describe what is happening and the engineer asks a few short questions, such as where the water shows, whether you have turned the supply off, and whether anything electrical is wet. The hourly rate is quoted before anyone attends.
• Making safe: before any searching, the engineer checks that the water and electrics are safe, and stops the supply if it is still running.
• History: when did it start, did it get worse after the heating or a tap was used, has anything been plumbed, drilled or moved nearby. The answers shorten the search.
• Quick checks: a meter test with everything off, a look at the visible pipework, appliance connections and stop taps, and a reading of how wet and how warm the affected surfaces are.
• Targeted methods: acoustic listening, thermal imaging, moisture mapping, pressure testing or tracer gas, chosen by what the first checks suggest rather than all at once.
• Confirming: a finding is not accepted until it is tested. A pipe run is isolated and pressure tested, or a suspected joint is checked with an endoscope, so that the fault is confirmed and not assumed.
• Stopping: the leak is stopped, by tightening a fitting, isolating a section or capping a branch, so that the property is safe overnight.
• Next step: a small fix is done on the spot, and for a longer repair the leak is stopped first and a written quote follows. The emergency leak repair page sets that out.

The methods used, and when each one fails

No method finds every leak, and a visit that pretends otherwise is selling comfort. The table lists what each method is good at and where it lets you down. Reading the right-hand column matters more than the middle one, because it explains why an engineer changes method halfway through a visit and why that is a normal part of the work.

Tracer gas, endoscopes and the rest

Tracer gas is a harmless, very light gas mixture that is pushed into an emptied and sealed pipe run. It rises through the smallest escape route and a sensitive detector picks it up on the surface. It finds leaks that are silent, slow and cold, and it is the method that most often settles a stubborn case. The gas arrives in a cylinder, which is charged once on top of the hourly rate, only when gas is actually used: the rate is £160 an hour, plus £80 for the cylinder. No VAT is charged. Tracer gas is not magic either. If the pipe cannot be emptied, or the leak is large enough to vent the gas straight away, other methods do the work.

An endoscope is a small camera on a flexible lead, passed through a hole about the size of a coin. It lets the engineer look inside a boxed pipe, a void under a bath or a gap behind a unit without taking the room apart. Pressure testing isolates part of the system, raises the pressure and watches a gauge. A section that holds is cleared, and a section that drops is the one to search. Dye testing adds colour to a suspected source and looks for it where it should not be, which is how the failing seal around a shower tray or the bad joint on a toilet connection is confirmed.

Moisture mapping records readings across a wall or floor and builds a picture of where the dampness is highest and how far it has spread. It does not find a pipe. It tells the engineer where to point the other methods, and it shows afterwards whether a repair has worked because the readings fall as the structure dries. Moisture work is quoted from from £175 an hour. No VAT is charged.

What emergency leak detection costs

Emergency attendance is from £220 an hour, on any day and at any time we are called, with the exact rate stated when you book. The rate is a fixed hourly rate quoted before we attend and never exceeded. Booking comes with no call-out fee and no travel charge: the rate starts when work starts. The visit is charged for the time spent working, a leak that is awkward, large or found late at night does not raise the rate, and the written findings are included in the hours. No VAT is charged.

The other rates apply when the job is a different kind of work. Standard detection, for a leak that is not an emergency, is £160 an hour. A leak on the supply pipe is £180 an hour. Heating and underfloor leaks are £200 an hour. Trace and access with a written report for an insurer is £200 an hour. The pricing page lays them all out, and the emergency leak detection cost guide works through what an emergency visit adds up to.

The total is rate multiplied by the hours the search takes. The honest unknown is the hours, and no one can read them off a stain. These worked examples show how the arithmetic goes at the standard and supply rates; an emergency visit is the same sum at the emergency rate.

What a leak visit finds, and what it cannot tell you

A visit can usually say whether water is escaping, which circuit or appliance it comes from, roughly where, and whether the fault is on your side of the property. It can give you a finding you can act on, and a written note of what was found and how it was confirmed.

It cannot see through a floor. It cannot promise that the first method will work, and it cannot say how long a repair will take until the pipe has been exposed. It cannot tell you the age of a leak from a stain, and it cannot say how much water has gone into the structure. A leak that is intermittent, such as a pipe that only weeps when the heating is on or when the loft tank is full, may not show on the night. The engineer may need to return when the circuit is in the condition that makes it leak.

Some findings are uncomfortable. The most common is that the cause is not where you thought: a ceiling stain traced to a shower tray seal in the bathroom above rather than a pipe. Another is that nothing is wrong. Ruling a leak out is a real answer, it is charged for the hours worked because that is the answer you asked for, and it tells you the stain is condensation, an old mark or a gutter, or something else that a plumber is not the right person for.

Where a method has failed to find the cause, the engineer says so plainly and says what the next step would be, with its likely hours, so you can decide. There is no pretending that a fifth method will work when the first four have not.

When the leak is not on your side of the property

In flats and terraces the water you can see is often not yours. A leak from a flat above, a shared riser, a communal pipe or the water company supply to the street can all show up in your home. Detection still earns its keep here, because finding the source is what lets you take the matter to the right party. Our job is to locate the leak and write down what was found, how, and where.

The practical rules are simple. Your pipes, taps and appliances inside your property are yours. A shared riser serving several flats belongs to the building. The supply pipe from the street to the boundary is the water company; from the boundary to your property it is usually the owner of the property. A leak that proves to be a neighbour's, a communal riser's or the water company's main is a located leak, and the hours spent finding it are charged at the rate you were quoted.

No find, no fee: where the edge is

No find, no fee waives the detection fee only when a live leak inside your own property cannot be located. That is a narrow promise with clear edges, and the full explanation with worked examples is on the no find, no fee page. The short version is that if the leak is confirmed live, is inside your own property, and cannot be located after the full search, the detection fee is waived. A located leak is charged, wherever it turns out to be. A visit that shows no leak exists is charged for the hours worked, as that is the answer.

The reason for stating it here is that people often ask whether it is worth calling an engineer when they are not sure there is a leak. If you are, the useful move is to confirm it first. A meter that moves with everything off, a pressure gauge that drops, a ceiling that gets wetter on a dry day are evidence. A smell or a feeling is a reason to book moisture mapping, not an emergency.

While you wait for the engineer

Stop the supply at the stop tap if you can reach it safely, move valuables and electrical items away from the wet area, and put a bucket or bowl under any drip. Do not use electrics near wet surfaces. The first hour of a burst pipe guide covers the steps in order. If you can, photograph the leak and the affected area, and write down the meter reading. The photo checklist shows what is worth capturing, and an engineer can usually do more with a good photograph and a time.

If you are not sure whether to ring, the emergency checker asks four short questions and gives a verdict. If you do not know who to ring in the first place, the who to call for a water leak guide separates a leak engineer from a plumber, a landlord and the water company.