If you have or suspect a gas leak, leave the affected area and call the National Gas Emergency Service on 0800 111 999 from outside or another safe place. Do not smoke, light flames, or turn electrical switches on or off. Open doors and windows if this is quick and safe. Turn the supply off at the meter only if you know how, can reach it safely and it is not in a cellar or basement.
This guide explains the order of action and what happens after the emergency call. It is not a substitute for calling.
Gas leak emergency checklist
- Open doors and windows if you can do so without delaying your exit.
- No flames or smoking. Extinguish naked flames only if immediately safe.
- Do not use electrical switches. Do not turn lights, sockets, boiler controls or appliances on or off.
- Turn gas off if safe. Use the meter emergency control only if accessible and understood.
- Get outside and call 0800 111 999. Keep people away and follow the operator’s instructions.
If there is a fire, explosion, structural damage or immediate threat to life, call 999 from a safe location.
1. Get people away from the leak
Move everyone out of the affected room or building. Help children, older people, disabled occupants and pets if you can do so without putting yourself in danger. Use a normal exit and do not operate an electric garage door, lift or door-release switch.
If the smell is in a cellar or basement, do not enter. Cadent and National Gas guidance says to evacuate rather than going down to reach a meter in that location.
2. Remove obvious ignition sources without creating another
Do not smoke, vape, strike a match, light a candle or use any naked flame. Do not operate a light switch, plug, thermostat, boiler control, extractor fan or appliance. Switching something off can create a spark just as switching it on can.
Do not go from room to room unplugging equipment. Leave the property and let the emergency service control the situation.
3. Ventilate only if it is safe
Open accessible external doors and windows as you leave. Natural ventilation can help disperse gas. Do not switch on a fan and do not delay evacuation to reach every window.
If the smell is overwhelming, you hear escaping gas or the route feels unsafe, leave immediately. Call from a safe distance.
4. Turn off the gas at the emergency control valve if safe
The emergency control is normally beside the gas meter. A typical lever turns a quarter-turn to close, but follow the meter arrangement and call-handler advice. Only act if you know which control it is and can reach it safely.
Do not enter a cellar, force a seized control, remove meter covers or touch pipe joints. If you cannot isolate it, get out and tell the emergency operator.
5. Call 0800 111 999
The National Gas Emergency Service is free and operates 24 hours a day in Great Britain. Call for a gas smell, suspected leak, suspected carbon monoxide emergency or a struck gas pipe, even if no gas smell is present after the strike.
Use a phone outside or in another safe location. The operator will give immediate instructions and decide the emergency response.
What information will the operator need?
- the full address and postcode;
- where the smell or leak is strongest;
- whether it is inside, outside or in a communal area;
- when it started and whether it is getting stronger;
- whether the gas supply is off;
- whether anyone feels unwell;
- whether a pipe has been struck or damaged;
- any cellar, basement or access issue; and
- where you will wait safely.
Do not try to find the leak
Do not use a flame, soapy water, a handheld detector or your sense of smell to trace pipework. Do not remove a boiler case, pull out a cooker or tighten a fitting.
Moving an appliance can worsen a damaged connection. Gas tightness testing and repairs require appropriate equipment and competence.
What if a builder or drill has hit a gas pipe?
Stop work, avoid electrical equipment and flames, move people away and call 0800 111 999 immediately. HSE and National Gas say a struck gas pipe must be reported even if no leak has been confirmed.
Do not attempt to clamp, tape or bury the damaged section. Give the operator the exact location and whether machinery is still running nearby.
What if the leak is outside?
Move away from the strongest smell, prevent smoking or flames in the area and call the emergency number. Keep vehicles and machinery away where possible without operating equipment in the affected zone.
Do not lift a manhole cover, inspect an excavation or approach a damaged service pipe. Warn others from a safe position.
What if the gas has already been turned off?
Still call the emergency service. Tell the operator who isolated it, when and whether the smell remains. Do not turn the supply back on to see if the smell returns.
HSE guidance says a supply should not be restored until the leak has been dealt with by a competent person. Appliances may also need safe relighting or separate repair.
What happens when the emergency engineer arrives?
The emergency response is aimed at finding the escape and making the situation safe. The engineer may test, isolate the supply or an appliance, and explain the next action. Give them clear access and disclose every affected area.
The emergency visit may not include a permanent appliance repair. If a boiler, cooker or internal installation is at fault, a suitably qualified Gas Safe registered engineer may be required afterwards.
Do not reconnect an isolated appliance
If an engineer labels, disconnects or isolates an appliance, do not remove the label, reconnect it or ask an unregistered person to do so. HSE says an appliance suspected of being unsafe must not be used until checked.
Keep the emergency paperwork and pass it to the repair engineer, landlord or managing agent.
Natural gas, LPG and carbon monoxide are different
The 0800 111 999 number is for natural-gas and carbon-monoxide emergencies in Great Britain. HSE says LPG users should contact their LPG supplier for a suspected LPG leak, following the supplier’s emergency arrangements.
Carbon monoxide has no smell. A carbon monoxide alarm or symptoms such as headache, dizziness, nausea, weakness, confusion, chest pain or breathlessness require fresh air and urgent action even when there is no gas odour.
When to get medical help
NHS guidance says to go outside and get medical advice as soon as possible if you think you may have carbon monoxide poisoning. Call NHS 111 for possible symptoms.
Call 999 or go to A&E for severe symptoms, including difficulty breathing, sudden confusion, loss of consciousness, weakness or chest or muscle pain. Do not drive yourself to A&E.
Advice for tenants
Call the gas emergency number yourself; do not wait for the landlord or agent. Once safe, notify them promptly and provide the emergency engineer’s information.
GOV.UK says landlords are responsible for keeping supplied gas equipment safely installed and maintained and for arranging the required gas safety checks. A tenant should not be asked to repair, reconnect or test gas equipment.
Advice for landlords and agents
Treat a report of a gas smell as an emergency, not a routine repair ticket. Tell the occupant to leave and call 0800 111 999. Do not send an unqualified maintenance worker to investigate a live leak.
After the emergency service makes the property safe, arrange qualified repair, keep records, communicate clearly with occupants and provide safe temporary arrangements where necessary.
Can I stay in the property?
Follow the emergency operator and attending engineer’s advice. Do not re-enter because the smell appears to have faded. Ventilation can reduce odour without proving the leak has stopped.
If you need medication, mobility equipment or help evacuating, tell the operator and emergency services immediately rather than going back alone.
When can repair work begin?
Only after the emergency has been controlled and the area declared safe for the relevant work. Gas appliance and installation repairs must be completed by a Gas Safe registered engineer competent for that appliance and work category.
A boiler booking service is not the first contact for an active leak. Use the emergency number first, then arrange the identified repair.
Frequently asked questions
Who do I call for a gas leak?
In Great Britain, call the National Gas Emergency Service on 0800 111 999 from outside or another safe place.
Can I use a light switch to see the meter?
No. Do not turn electrical switches on or off. Leave and tell the operator that the meter cannot be reached safely.
Should I call a Gas Safe engineer before the emergency line?
No. For an active or suspected leak, call 0800 111 999 first. Arrange appliance repair after the emergency is made safe.
What if I cannot smell gas anymore?
Still follow the advice you were given and do not restore the supply. A faded smell does not prove the source is safe.
Related boiler-help guides
- What to do if you smell gas
- Carbon monoxide alarm going off
- What happens after a gas appliance is made safe?
- How to check a Gas Safe engineer
Has the gas leak been isolated and made safe?
After the emergency response, book a fixed-price Incredaboil repair if the boiler is the appliance that still needs attention.