Do these six things before we get there
Most of the damage in a leak happens in the first hour, and nearly all of it is avoidable from inside the property. None of this needs a tool.
- Close the internal stopcock. In a Victorian or Edwardian terrace it is usually under the kitchen sink, in the cupboard under the stairs, or on the wall where the supply comes up through the floor at the front of the house. In a purpose-built flat it is more often in the airing cupboard, under the bath panel or behind an access hatch in the hallway. Turn it clockwise. If it is stiff, ease it rather than forcing it — a snapped spindle on a seized valve turns a leak into a flood.
- Open the kitchen cold tap. That empties the rising main and takes the pressure off the split. If the flow slows to a dribble within a minute or two, the leak is inside the house and now under control. If it keeps running at full bore, the water is arriving from upstream of the stopcock, which puts the fault on the buried supply pipe between the boundary and the wall.
- If it is the heating, shut the valves. Turn the boiler off and close both valves on the leaking radiator or towel rail. A sealed heating system only holds its own water, so it will empty itself and stop rather than run all night.
- Keep the water away from the electrics. Water tracking along a ceiling void finds downlights and ceiling roses before it finds anything else. If the wet area is anywhere near a light fitting, switch the lighting circuit off at the consumer unit and leave it off until the ceiling has been opened and dried.
- Relieve a bulging ceiling, do not pull it down. A sagging plasterboard ceiling is holding several litres. Pierce it once at the lowest point with a screwdriver, over a bucket, and let it drain. That usually saves the board. Left alone it comes down in one piece, and it takes the light fitting with it.
- Photograph everything before you mop. Wet floor, stained ceiling, the puddle, the meter reading. Insurers assess what they can see, and by the time a loss adjuster looks at it the evidence has been cleaned up. There is more on this in our insurance claims guide.
What we actually do when we arrive
An emergency visit is not a look and a quote. It is an isolate-trace-repair sequence, run in that order so nothing gets opened up on a guess.
- Isolate and stabilise. Supply off, system drained or the affected circuit valved out, standing water cleared from the area we need to work in.
- Prove the loss and size it. The pipework is pressure-tested so we know the loss is real, roughly how fast it is going, and which circuit it is on. A system that holds pressure with the heating valved off and drops with it open tells us where to look before anything is lifted.
- Trace it. Acoustic correlation on pressurised pipework, thermal imaging to follow hot runs through screed and plasterboard, a moisture meter to map the wet zone back to its high point, and tracer gas on a drained pipe when the first three cannot separate two candidates. Tracer gas is non-invasive: hydrogen and nitrogen are pushed into the empty pipe and picked up at the surface where they escape.
- Open one access point. One board, one section of ceiling, one core through the screed — sized to the repair, cut where the leak is, not where it is convenient.
- Repair the pipe. Not a clamp and a promise. The failed section comes out and a new one goes in.
- Test under pressure before closing up. The repair is brought back to working pressure and held while we watch it, with the access still open.
- Make the opening good. Board, skim, screed, floor, tile, paint. That part is ours.
What we find most often on emergency calls in London
The property type narrows the fault before anyone gets through the door.
| Property | What it usually turns out to be |
|---|
| Victorian and Edwardian terrace | The old lead supply pipe under the front path, or the lead-to-copper transition at the stopcock, where fifty years of movement has finally opened the joint. Inside, 15mm copper clipped to the joists under the floorboards, corroded where it passes through a notch and has been sitting in damp timber. |
| Purpose-built block | The communal riser in the service cupboard, which serves flats above and below you. The water is in your flat; the pipe frequently is not yours. Establishing that early changes who pays. |
| Converted flat in a period house | A bathroom added over what used to be a bedroom, so the waste and supply run across joists that were never designed for them. Boxed-in soil stacks in the corner of the bathroom are the other common one, because nobody looks inside a boxing until it is wet. |
| New build or recent refurbishment | Push-fit joints in a ceiling void or a floor build-up, assembled without the insert fully home. They hold for a year or two and then let go. Screed floors with underfloor heating hide the loss for months. |
| Basement conversion | The mains entering through the retaining wall, the sump and pump chamber, and penetrations through the tanking. Water here has nowhere to drain to, so it sits. |
If your symptom is on that list already, the symptom pages go into more detail: a burst pipe, water coming through a ceiling, or a wet patch with no obvious source.
The repair itself
What goes back in depends on what came out.
- Copper. The failed length is cut out and replaced. Soldered where there is room and no fire risk to surrounding timber, press-fitted or compression-jointed where there is not. A pinhole in a 15mm run almost never comes alone, so we look along the rest of the run before closing up.
- MDPE. Blue plastic supply pipe is repaired with a proper compression coupler, or the run is replaced end to end where the pipe is old, shallow or has been damaged by a previous dig.
- Lead. We do not patch lead. A lead pipe that has failed once is work-hardened along its whole length, so the section is replaced.
- Plastic push-fit. Remade with the insert seated, the pipe cut square and the joint fully home, which is where most of these failed in the first place.
- Heating pipework. Repaired, then the system is refilled, vented and brought back to pressure with you there to see the gauge hold.
Putting the building back, which is the part most firms leave
The common ending to a London leak job is a repaired pipe, a hole in your ceiling and a card for a plasterer. We do not work that way, because the making good is in-house: handymen and builders on the same firm as the engineers.
That means the lifted floorboards go back down and the finish floor over them is relaid, the cut in the screed is filled and levelled ready for the covering, the plasterboard is replaced and skimmed, the ceiling is repaired and painted, and tiling is cut in and grouted to match. One firm, one job, one invoice, and nobody arguing about whose damage the hole is.
When it is not an emergency, and when it is not us
Calling an emergency engineer for something that can wait costs you money. These can wait for a normal appointment:
- A dripping tap or a slowly weeping radiator valve with a towel under it.
- A stain on a ceiling that is dry, hard and sharply ringed — that leak has already stopped.
- A boiler you top up once or twice a year. That is normal.
And these are not ours at all. If you smell gas, that is the national gas emergency service, immediately, not a plumber. Damp that appears only during and after rain, on a chimney breast or below a roof line, is a roofing job. Sewage backing up outside your boundary is your water company. Black mould in a cold corner with no water history is condensation, and a leak engineer will find nothing.
What it costs, honestly
The rate is £150 per hour and it is agreed before we attend. It does not rise for a difficult property, awkward access or an evening visit. What we cannot tell you in advance is the total, because that depends on how many hours the job takes and what materials go in — anyone quoting you a fixed total for a leak they have not seen is guessing. The rate cannot change; the number of hours is what we work to keep down. There is a fuller breakdown on the pricing page.
No find, no fee applies to the detection: if we do not find the leak, you do not pay for the time we spent looking. Every job comes with a written leak detection report set out for a trace and access claim, so if you are claiming, your insurer gets what it asks for the first time.
