If you can smell gas right now, stop reading and act.
Leave the property. Do not touch any switches. Once outside, call the National Gas Emergency Service on 0800 111 999. It is free and staffed twenty-four hours a day.
The sequence
1. Do not touch anything electrical. No light switches on or off, no plugging or unplugging, no doorbell, no mobile phone indoors, no smoking, no lighters or matches, and nothing that makes a spark. Any spark or flame can ignite leaking gas.
2. Open external doors and windows to ventilate, if you can do so without operating anything electrical. It helps the gas disperse and reduces the risk of an explosion.
3. Turn the gas off at the meter if you can reach it safely. The emergency control valve is usually a lever or tap on the pipe leading from the meter. Turn it ninety degrees so the handle sits across the pipe. Only do this if you can get to it without operating any electrical switches.
4. Get everyone out, including pets, and into the fresh air.
5. Call 0800 111 999 from outside or from a neighbour’s house. The call is free, and they will send an emergency engineer to make the situation safe.
6. Wait outside, and do not go back in, until the emergency engineer confirms it is safe. That can take some hours.
What a gas leak smells like
Natural gas is odourless. The rotten egg or sulphur smell is added deliberately so leaks can be found.
It may be strong near the source and faint elsewhere, worse in enclosed spaces, and more noticeable when the heating is running.
Trust it even if it is faint. A small leak can become dangerous, and exposure dulls your sense of smell, so a weak smell does not reliably mean a small leak.
Other signs of a leak
Smell: gas near an appliance, or a smell that comes and goes as the boiler runs.
Visual: houseplants dying near an appliance, a yellow or orange boiler flame where it should be blue, soot or black marks around an appliance.
Sound: hissing near gas pipes, whistling near the meter, or roaring or whistling from the boiler.
Physical: headaches, dizziness, nausea or breathlessness that improve when you go outside.
After the emergency
The emergency engineer’s job is to make the situation safe. Once they have, you may still need a Gas Safe registered engineer to repair the fault itself before the appliance can be used again.
Carbon monoxide is a separate danger
Carbon monoxide comes from an appliance burning gas incorrectly. Unlike a gas leak it is completely odourless and you cannot detect it without an alarm.
Symptoms are headaches, dizziness, nausea and vomiting, tiredness, confusion, stomach pain and breathlessness. They are easily mistaken for flu, and the giveaway is that they improve when you leave the house.
If a CO alarm sounds, get everyone out, open windows, call 0800 111 999, and get medical advice for anyone with symptoms.
CO alarms are legally required for landlords in any room with a fixed combustion appliance. They cost very little and they save lives, so every home should have one regardless.
Common causes of gas leaks
Old or faulty appliances. Boilers, cookers and gas fires can all develop leaks as joints and seals degrade with age. Annual servicing catches this.
Badly fitted appliances. An appliance that was not installed by a Gas Safe registered engineer may have unsafe connections. Always check your engineer’s Gas Safe ID card.
Damaged pipework. DIY work, building projects and accidental damage all puncture or loosen gas pipes. Even small damage needs a professional repair. Never attempt work on gas pipework, an appliance or a flue yourself.
Corroded connections. Joints corrode over time, particularly in damp locations, which is one reason an annual inspection matters.
Preventing it
An annual boiler service is the best single way to prevent gas and carbon monoxide problems. A Gas Safe engineer checks the components, the connections and the safety devices every year.
- Annual boiler service by a Gas Safe registered engineer
- A working CO alarm in every room with a gas appliance
- Know where your gas meter emergency valve is
- Never block ventilation to a gas appliance
- Only use Gas Safe registered engineers, and check the card
- Landlords need an annual gas safety certificate by law
The numbers
Gas emergency: 0800 111 999. Free, twenty-four hours. Call this first.
Mend Your Home: 07960 066300. Call us once the supply has been made safe and we will handle the repair.
Frequently asked
What does a gas leak smell like?
Natural gas has no smell of its own. A strong rotten egg or sulphur odour is deliberately added so leaks can be detected. It may be strong near the source and faint elsewhere, and worse in enclosed spaces.
Should I call the gas emergency line even if the smell is faint?
Yes. Prolonged exposure desensitises your sense of smell, so a faint smell does not reliably mean a small leak. The line is free and staffed twenty-four hours, and they would far rather attend a false alarm.
What is the difference between a gas leak and carbon monoxide?
A gas leak is unburnt gas escaping, and you can smell it because of the added odorant. Carbon monoxide is produced by an appliance burning gas incorrectly, and it is completely odourless. You cannot detect it without an alarm, which is why every home with a gas appliance should have one.