If you smell gas, open the doors and windows, do not touch any switch, flame or phone indoors, turn the gas off at the meter if you can do so safely, get everyone outside and call the National Gas Emergency Service on 0800 111 999. The call is free and an engineer will come out to make the property safe.
That sulphur, rotten-egg smell in the hallway is the one household smell you should never sit and think about. Mains gas has no smell of its own. Suppliers add the odour so that the smallest escape is noticed long before it reaches a dangerous level, which means the moment you notice it is the moment to act. Here are the steps in the right order, then what happens after the emergency engineer leaves, because that part surprises most people. Our gas leak detection service only enters the picture once the supply has been made safe.
The steps, in order
Do these in order. Each one reduces the chance of a spark meeting a pocket of gas.
- Put out any flame. Cigarettes, candles, a hob ring, an open fire or wood burner. If the boiler is running, leave it: switching it off means touching a control, and the valve at the meter will stop it anyway.
- Open doors and windows. Get air moving through the house, and leave them open when you go out.
- Do not use any electrical switch. Lights, sockets, the doorbell, the extractor fan. Leave everything exactly as it is, on or off. A switch makes a tiny spark inside its casing and that is enough.
- Turn the gas off at the meter, if it is safe. The emergency control valve is a lever on the pipe beside the meter. Turn it a quarter turn so the lever sits across the pipe rather than along it. Skip this step if the meter is in a cellar or basement, because gas can pool at low level and you should not go down there.
- Get everyone out. Children, anyone elderly or unwell, pets. Go outside into fresh air, not into a garage.
- Call 0800 111 999 from outside. Use your mobile once you are clear of the building, or a neighbour’s phone. The National Gas Emergency Service line is free and open at any hour. Give the address, say what you smell and where, and whether the meter is off.
- Stay out until told otherwise. Do not go back in for coats or keys. The engineer will tell you when it is safe.
If anyone feels dizzy, sick or has a headache, say so on the call and get medical advice once outside. Those symptoms can also point to carbon monoxide, which has no smell, and the same number covers both.
Why the phone and the light switch matter so much
People know about naked flames. The switches catch them out. A gas escape only becomes dangerous once it mixes with air in the right proportion, and at that point almost any spark will do: a light switch, a doorbell, the hob ignition pressed to “see if it works”, even unplugging a charger. Mobile phones are on the list for the same reason. The other habit worth breaking is the sniff test. Do not walk round the house working out where the smell is strongest. Note where you first noticed it, tell the engineer, and let them find it with a detector.
Find your emergency control valve before you need it
Ten minutes on a quiet Sunday saves a frightened fumble later. In most Cornish homes on mains gas the meter is in a white box on an outside wall, in a cupboard under the stairs, or in the garage. In older terraces in Truro, Camborne and Redruth it is often inside, low down near the front door. Find the lever, check it moves, and show everyone in the house. If you run a holiday let, put a photo of the meter and the emergency number in the welcome folder for the guest who smells gas at midnight in a house they do not know.
Many Cornish farms, hamlets and coastal properties are off the gas grid and run on LPG. The steps above still apply, and the emergency number is printed on the tank, the cylinders and your supplier’s paperwork.
What the emergency engineer does
The engineer who arrives works for the gas emergency service, not for your supplier and not for a repair firm. Their job is narrow and there is no charge for it: find out whether gas is escaping, and make the property safe. That means one of three outcomes.
- No escape found. The smell was something else (a drain, a neighbour’s bonfire, an appliance that has since gone out) and the supply is left on.
- A leak on an appliance. The engineer disconnects or isolates that appliance, labels it as not to be used, and leaves the rest of the supply live.
- A leak on the pipework, or one they cannot isolate. The engineer caps the supply at the meter and labels it. Nothing gas-powered in the house will work until a Gas Safe registered engineer has repaired the fault and re-tested the installation.
The emergency engineer will not carry out the repair. That is how the service is set up: attend, make safe, move to the next call. They leave you with a safe house, a capped supply and a job to organise.
Why a capped supply needs a Gas Safe registered engineer
Anyone who works on a gas installation in the UK must be on the Gas Safe Register. It is the law, and it is why a handyman or a plumber without gas registration cannot uncap your meter, however competent they are elsewhere. Ask to see the engineer’s Gas Safe ID card. The back lists the work they are registered for.
The Gas Safe engineer will start with a tightness test: the installation is pressurised and watched for a set period to see whether the pressure holds. If it drops, there is a leak somewhere on the pipework, and the search begins. In a modern flat with a short run of visible copper, that search is quick. In a 200-year-old granite cottage in Penwith where the pipe was chased into the wall decades ago and runs under a suspended timber floor, it is a different job, and the point at which many engineers call in a specialist rather than opening up floors by guesswork.
Where pinpoint gas leak detection fits
Our part of the job is locating the exact point on the pipe that is failing, so the Gas Safe engineer can expose one small area, repair it and re-test, rather than lifting half a floor. We use gas detection instruments to follow the escape, and where the pipe run is buried or inaccessible we use the same tracer gas leak detection method that finds hidden water pipes: a safe, inert gas mixture is introduced into the isolated pipework and traced from the surface with a detector that picks it up through screed, boards and plaster.
Two things to be clear about. We do not work on the gas installation itself, and we do not attend gas emergencies. The emergency service makes safe, we locate, a Gas Safe registered engineer repairs and re-commissions. Where the search means opening floors or walls, our report marks and photographs the location for the repairing engineer and for any buildings insurance claim covering the access damage. Our guide to what happens on a leak detection survey covers the visit itself, and how long leak detection takes explains what governs the timescale.
A faint whiff near the boiler cupboard when the heating fires, or a smell a visitor notices that you have stopped registering, deserves the same call. Those small, intermittent escapes are exactly the leaks a tightness test confirms but a visual check cannot find.
| What you notice | What it usually means | What to do |
|---|---|---|
| Strong rotten-egg smell indoors | Gas escape, possibly significant | Steps above, out of the house, call 0800 111 999 |
| Faint smell near one appliance | Appliance or connection fault | Same steps, same call. Engineer may isolate the appliance only |
| Hissing near the meter or pipework | Escape under pressure | Do not investigate. Out of the house, call 0800 111 999 |
| Supply capped, tightness test fails, no visible fault | Hidden leak on buried or concealed pipework | Specialist tracing, then Gas Safe repair |
| Headache, dizziness, no smell | Possible carbon monoxide | Fresh air, medical advice, call 0800 111 999 |
If you rent, tell the landlord or agent in writing as soon as the emergency engineer has left, because the repair is theirs to arrange. For everything on the water side of the house we provide leak detection across Cornwall with the same approach: locate it precisely, open up as little as possible, and hand over a report.
Frequently asked questions
Is it safe to use my mobile phone if I smell gas?
Not inside the property. Walk outside first, well away from the building, then make the call. The chance of a phone causing a spark is small, but the emergency service asks you not to use one indoors, and the front door is only a few steps away.
Does the emergency engineer fix the leak?
No. The National Gas Emergency Service engineer confirms whether gas is escaping and makes the property safe, which may mean capping the supply. There is no charge for that visit. The repair, and the re-test that follows it, must be done by a Gas Safe registered engineer that you arrange yourself.
The tightness test failed but nobody can find the leak. What now?
That is where pinpoint detection helps. Gas detection instruments and tracer gas testing follow the escape through floors and walls and narrow it to a small area, so the Gas Safe engineer exposes one spot rather than lifting floors on guesswork. You get a marked-up report for the repair and any claim.
I smelt gas once and now I cannot smell it. Do I still need to call?
Yes. Gas smells come and go with draughts, pressure changes and whether an appliance is running, and your nose stops noticing a smell quickly. An intermittent smell is still an escape. Call 0800 111 999, let the engineer check, and if the tightness test shows a drop, have the pipework traced.
Supply capped and nobody can find it?
Once the emergency engineer has made your home safe, we locate the exact point of the leak on concealed or buried pipework, so the Gas Safe repair is small and targeted, with an insurance-ready report marking the spot.
