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Gas smell in the house? Here’s what it usually means

Guidance last checked on against UK safety regulation and the sources behind our service pages.

If you smell gas, don't use switches or flames, open doors and windows, turn off the meter unless it's in a cellar, get everyone out and call 0800 111 999. It is the National Gas Emergency Service's free line, open day and night. Never go down to a meter in a cellar or basement, and stay out until the emergency engineer says it is safe to go back in.

Gas smell in the house: the questions people ask

What does a gas leak smell like?

Mains gas has no smell of its own. A harmless chemical called mercaptan is added to it so that a leak can be noticed, and it gives off a strong, sulphur-like smell, like rotten eggs. Act on that smell every time: don't use switches or flames, open the doors and windows, turn the gas off at the meter unless it is in a cellar or basement, get everyone out and call 0800 111 999.

How do I turn the gas off at the meter?

Look for the emergency control valve: a handle on the pipe next to the gas meter. With the gas on, the handle lines up with the pipe; a quarter turn either way, so it sits across the pipe, turns the gas off. A meter box outside may need its key, and in a block of flats the meter may be in a communal area. If the meter is in a cellar or basement, don't go down to it.

What should I do if I smell gas outside?

A smell of gas outside, in the street or near a building, is reported on the same number: call the National Gas Emergency Service free on 0800 111 999 as soon as you can. Don't smoke or light a flame nearby, and leave the emergency engineer to find where it is coming from. If you or a builder hits a gas pipe while digging, call the same number, even if you can't smell gas.

Can you smell carbon monoxide?

No. Carbon monoxide has no colour, taste or smell: you need an alarm to detect it. If the alarm sounds, or anyone has headaches, dizziness or nausea with no gas smell, stop using gas appliances, open doors and windows, get everyone out and call 0800 111 999. Fresh air alone won't treat exposure: call NHS 111 urgently, or 999 if anyone is struggling to breathe, confused, unconscious, weak or has chest or muscle pain. Don't drive yourself to A&E.

What happens when the gas emergency engineer comes?

The emergency engineer comes from your local gas network and carries ID, so check it before you let them in. They need to come inside to make the property safe, and may take readings around your home and your neighbours' homes too. They tell you what they found and what happens next, and the gas supply or an unsafe appliance may be turned off and left off until it is repaired.

Who repairs a gas leak inside my home?

It depends where the leak is. The gas network looks after the pipes in the street and the pipe up to your meter, and arranges repairs to those itself. Your gas supplier, the company that bills you, is responsible for the meter. The pipes from the meter to your appliances, and the appliances, are yours, or your landlord's if you rent and the landlord supplied them, and the engineer who repairs them must, by law, be Gas Safe registered.

What to do, in order

  1. 1. Don't use switches or flames, then open the doors and windows

    Don't turn any light or power switch on or off, don't use anything that could make a spark, and don't smoke or light a flame. Put out any naked flame, then open the doors and windows to let fresh air in.

  2. 2. Turn the gas off at the meter, unless it is in a cellar

    If you know where the gas meter is and can reach it, turn the handle on the pipe beside it a quarter turn, so it sits across the pipe. If the meter is in a cellar or basement, don't go down to it.

  3. 3. Get everyone out and call 0800 111 999

    Leave the property with everyone in it, then call the National Gas Emergency Service free on 0800 111 999, day or night. Tell the adviser if anyone at home is vulnerable, and follow the advice they give you.

  4. 4. Stay out until the emergency engineer gives the all-clear

    Wait outside, and don't go back in for anything until the emergency engineer says it is safe. Check their ID before you let them in: they need to come inside to make the property safe.

  5. 5. Leave off whatever the emergency engineer turns off

    Follow the emergency engineer's advice. If they leave the gas supply or an appliance turned off, don't turn it back on or use it: a Gas Safe registered engineer has to repair it and check it is safe first.

  6. 6. Get medical help if anyone feels unwell

    Call 999 if anyone is struggling to breathe, confused, unconscious, weak or has chest or muscle pain. For a headache, dizziness, nausea or tiredness, call NHS 111 urgently and mention carbon monoxide. Don't drive to A&E: ask someone to drive you or call 999.

What not to do

  • Don't turn any light or power switch on or off, use anything that could make a spark, smoke, or use a match or lighter — any of them can ignite escaping gas
  • Don't go down into a cellar or basement to reach the gas meter, even if that is where it is — leave the building instead
  • Don't try to find the leak, or to confirm there is one, yourself — that is the emergency engineer's job, and any gas work after it is for a Gas Safe registered engineer
  • Don't go back inside for anything until the emergency engineer has given you the all-clear
  • Don't turn the gas back on at the meter, or use an appliance the emergency engineer has turned off, until the emergency engineer or a Gas Safe registered engineer has checked it and told you it is safe — HSE says it is illegal for anyone to use a gas appliance they suspect is unsafe
  • If you smell gas, or a carbon monoxide alarm sounds: don't smoke, light a flame or touch light switches, open the doors and windows, turn the gas off at the meter if you can reach it safely and it isn't in a cellar or basement, get everyone out, and call the National Gas Emergency Service free on 0800 111 999 before anything else — before calling us

When to request help

Only once the emergency engineer has made the property safe. If they find the fault is on your side of the meter, in a gas appliance or the pipework leading to it, request a Gas Safe registered engineer to repair it, and leave off whatever they turned off until it is fixed. If you rent, tell your landlord or letting agent before booking: your landlord must make sure the gas equipment they supply is safely installed and maintained by a Gas Safe registered engineer, and if a heating appliance has been disconnected, HSE says your landlord must provide you with emergency heating. Treat it as a same-day job if the gas is off and you have no heating in cold weather, or vulnerable people at home. The Hero Agreement requires current Gas Safe registration for any gas work through London Heroes.

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Related questions

Is the gas emergency number free to call?
Yes. 0800 111 999 is the National Gas Emergency Service's free 24-hour line for England, Scotland and Wales, for a smell of gas or a suspected carbon monoxide leak. If your home runs on LPG from a bulk tank, call the emergency number on the tank or the meter instead, and don't go to the tank to turn the gas off. If you are deaf or have hearing or speech difficulties, you can call it through the Relay UK app by dialling 18001 0800 111 999.
What if I'm not sure it's gas I can smell?
Call 0800 111 999 anyway. The line is there for anyone who smells gas or thinks there could be a leak, and the adviser tells you what to do next. Only an engineer can confirm whether there is a leak, so open the doors and windows and call rather than waiting to be sure.

General guidance, not a substitute for an on-site professional assessment — and never for the gas emergency line (0800 111 999) if you smell gas.