What to do if you smell gas: step by step
Natural gas has no smell of its own. An odorant is added so that leaks can be noticed, which is why gas smells of rotten eggs or sulphur. If you notice that smell near the boiler, the meter or any gas appliance, follow these steps in order.
- Do not operate anything electrical. Do not switch lights, sockets or appliances on or off, including the boiler controls, and do not press a doorbell or use an entry phone. A switch can make a small spark.
- Put out any naked flames. Do not smoke, strike matches or use a lighter.
- Open doors and windows to let the gas disperse.
- Turn off the gas at the emergency control valve if you can reach it safely. It is usually a lever on the pipe next to the gas meter. Turn the handle so it sits at a right angle (across) to the pipe. If the meter is somewhere the smell is strong, or you cannot get to it quickly, skip this step.
- Get everyone out of the property, including pets, and move away from the building.
- Call the National Gas Emergency Service on 0800 111 999 once you are outside. In Northern Ireland, call the Northern Ireland Gas Emergency Service on 0800 002 001. Use a mobile phone outside or a neighbour's phone, not a phone inside the property.
- Wait outside at a safe distance until the emergency engineer arrives and tells you it is safe to go back in.
If anyone feels unwell, with a headache, dizziness, nausea or breathlessness, get them into fresh air and seek medical help. Tell the call handler if anyone has symptoms.
0800 111 999 covers mains natural gas in England, Scotland and Wales. If your home uses LPG from a tank or bottles, call your LPG supplier's emergency number, which is usually shown on the tank, the bottles or your bill.
What not to do
- Do not try to find the leak yourself, and never use a flame to look for it.
- Do not press reset on the boiler or turn it on to see whether it works.
- Do not remove the boiler casing or touch the gas valve, pipes or fittings.
- Do not turn the gas back on at the meter until an engineer says it is safe.
- Do not use anything that could spark, including light switches, doorbells, entry phones and electric garage doors.
- Do not assume someone else has reported it. If you smell gas in a shared building or in the street, call as well.
- Do not go back inside to collect belongings once you have left.
What happens next
The emergency service is run by the gas networks, not by your energy supplier, and the visit is free. When you call, the adviser will ask for your address, where the smell is and how strong it is, whether anyone is unwell and whether you have turned off the gas. They will give you safety advice over the phone and send an emergency engineer. The networks work to targets of reaching uncontrolled escapes within one hour and controlled escapes (where the gas has been turned off) within two hours.
When the emergency engineer arrives, they will:
- check for gas in and around the property with a detector
- trace where the gas is coming from and make the situation safe
- repair the leak if it is on the network's supply pipe or at the meter
- isolate or cap off an appliance or a section of your pipework if the leak is on your side of the meter
- attach a warning label to anything that must not be used
The emergency engineer does not repair boilers or your internal pipework. If the leak is on the boiler, a gas pipe inside your home or another appliance, you will need a Gas Safe registered engineer to repair it before it is used again. Until then you may be without gas heating, hot water or cooking. Once the repair is done and the gas is back on, the boiler may show an ignition fault such as Baxi E133 or Ideal L2 on its first start while air clears from the gas pipe, and the engineer will deal with that as part of putting it back into service.
When you book a repair, always ask to see the engineer's Gas Safe ID card, which shows their photo, licence number and the work they are qualified to do. Our boiler service guide explains how to check it.
Common reasons for a gas smell near a boiler
| Possible cause | What it means | Who deals with it |
|---|---|---|
| Leaking joint or fitting on the gas pipe to the boiler | Gas escaping on your pipework | Emergency service makes safe, Gas Safe engineer repairs |
| Faulty gas valve or internal seal in the boiler | Gas escaping inside the appliance | Emergency service makes safe, Gas Safe engineer repairs |
| Leak at the meter or regulator | Gas escaping on the supply side | Emergency service |
| Gas hob or fire left on without lighting | Unburnt gas released indoors | Call the emergency service and follow their advice |
| Smell coming from outside, such as roadworks or a neighbour's property | Gas escaping nearby | Emergency service |
You cannot tell which of these it is by smell alone, so treat every gas smell as a possible leak.
Gas leaks and carbon monoxide: the difference
A gas leak and carbon monoxide (CO) are different hazards, and you can have one without the other.
| Gas leak | Carbon monoxide | |
|---|---|---|
| What it is | Unburnt natural gas escaping | A poisonous gas produced when gas, oil, coal or wood burns without enough air |
| Smell | Rotten eggs, because an odorant is added | None. You cannot see, smell or taste it |
| Main danger | Fire or explosion | Poisoning, which can be fatal |
| How you know | The smell | A carbon monoxide alarm, symptoms, or signs such as soot around an appliance |
| What to do | Follow the steps above and call 0800 111 999 | Get into fresh air, call 0800 111 999 and seek medical help |
Because carbon monoxide has no smell, a boiler that smells fine can still be producing it. Every home with a fuel-burning appliance should have a working carbon monoxide alarm. If yours sounds, see our guide on what to do when a carbon monoxide alarm is going off.
Preventing gas leaks
Many gas problems at the boiler come from worn seals, loose fittings or damage that an annual service would pick up. Have your boiler and other gas appliances serviced every year by a Gas Safe registered engineer, and never let anyone who is not registered work on them. If you rent, your landlord must arrange a gas safety check every 12 months and give you a copy of the record. Keep the area around the meter clear so you can reach the emergency control valve quickly, and make sure everyone in the house knows where it is and how to turn it off.