Smell Gas? What to Do Immediately
If you smell gas, this is not a repair booking — it's an emergency call. Get everyone out of the property, don't operate any electrical switches, and call the National Gas Emergency Service free on 0800 111 999, which runs 24 hours a day. They attend as an emergency, make the situation safe, and are separate from (and prior to) whoever eventually repairs your boiler.
Do this immediately
Get everyone out of the property. On the way, open doors and windows if you can do so without delay. Do not operate any electrical switches — on or off — including light switches, doorbells and mobile phones inside the property, because a spark is the risk being avoided. Do not smoke or use any naked flame. If you know where the emergency control valve is (usually by the meter) and can reach it safely, turn the gas off at the handle.
Once outside and clear, call 0800 111 999. Give the address and describe what you've noticed. They will advise you and attend — this is what the service exists for, it's free, and calling about a smell that turns out to be nothing is entirely acceptable and preferable to the alternative.
What happens next
The emergency engineer's job is making the situation safe: locating and isolating the escape, checking the installation, and capping or disconnecting anything unsafe. They are not there to repair your appliance — once the property is safe, the repair is a separate job for a Gas Safe registered engineer, which is where our network picks up.
If an appliance is found at fault it may be labelled and disconnected. That label is meaningful: don't reconnect or use the appliance until a Gas Safe registered engineer has repaired and re-tested it. Doing so is both dangerous and, for landlords, a serious compliance failure.
Symptoms and other warning signs
Natural gas is odourised deliberately so leaks smell — that distinctive 'rotten egg' additive is a safety feature. Other signs of a gas escape: hissing near pipework or appliances, dead vegetation over a buried supply pipe outside, and dust or soil blowing near the meter. Feeling dizzy, nauseous or unwell alongside a gas smell means fresh air and medical advice, not investigation.
Distinguish from carbon monoxide, which is odourless: a CO problem gives you no smell at all, only symptoms and possibly an alarm. Both are emergencies with the same first move — everyone out — and both are covered by 0800 111 999 for the immediate safety response. Our carbon monoxide guide covers the CO-specific detail.
Prevention and the boundary line
Prevention is unglamorous: annual servicing of every gas appliance by a Gas Safe registered engineer, prompt attention to any fault, never blocking ventilation, and never allowing unregistered work on gas. Landlords add the annual gas safety check and CP12 record on top, as a legal duty. Those measures are why gas escapes are rare relative to the number of appliances in use.
And the boundary this whole site respects: gas work is for Gas Safe registered engineers, full stop. There is no homeowner-level gas repair, no acceptable improvisation, and no guide anywhere on this site that will tell you otherwise. Safe checks stop at the boiler case; everything inside it belongs to someone with a card you can verify on the Gas Safe Register.
| Step | Action |
|---|---|
| 1 | Everyone out of the property |
| 2 | Open doors and windows on the way if you safely can |
| 3 | No electrical switches, no flames, no smoking |
| 4 | Turn off at the emergency control valve if safely reachable |
| 5 | Call 0800 111 999 free, 24 hours, from outside |
| 6 | Don't use any labelled appliance until a Gas Safe engineer clears it |
Knowing the emergency number before you need it
Save it now: the National Gas Emergency Service on 0800 111 999, free and answered 24 hours. The decision to call should never involve looking anything up — if you smell gas, everyone leaves the property, no electrical switches are touched, and the call is made from outside. Knowing that sequence cold is worth more than any amount of reading in the moment it matters.
Frequently asked questions
What number do I call if I smell gas?
The National Gas Emergency Service on 0800 111 999 — free, 24 hours a day. Call from outside the property, not from inside, and don't use electrical switches on your way out.
Should I turn the gas off myself?
If the emergency control valve by the meter is safely reachable, turning it off is helpful. If it isn't reachable without delay or risk, leave it — getting everyone out and calling matters more.
Is it a false alarm if the smell goes away?
Still call. Escapes can be intermittent and ventilation can disperse the smell without fixing the cause. The service would far rather attend a false alarm than the alternative, and there's no charge.
Who repairs the appliance afterwards?
The emergency service makes things safe; a Gas Safe registered engineer performs the repair. Our network arranges that follow-up — but only after the property has been made safe.
Where written advice reaches its limit
Guidance like this can tell you what usually causes a symptom, but only an engineer with instruments on your actual appliance can confirm it. If what you're seeing doesn't quite match any pattern described here — or matches several at once — that ambiguity is itself useful information to hand over. Our engineers do this triage daily, and an honest one will tell you on the phone when your problem sounds like a cheap fix, a bigger job, or something that isn't the boiler's fault at all.
Carbon monoxide safety: symptoms, alarms and what to do — essential reading for every home with a fuel-burning appliance.