Gas Emergency Advice
Smell Gas? What to Do Right Now
If you smell gas or suspect a gas leak in your London home, leave, get to a safe place outside and call the National Gas Emergency Service on 0800 111 999 immediately. You do not need proof before reporting it. For suspected carbon monoxide symptoms, get fresh air and call NHS 111, or 999 if serious, without waiting for the gas call.
Call with your postcode, the boiler make and any fault code showing.
- Gas Safe registered: 648977
- Phone line open 24/7
- Same-day appointments available
Suspected Gas Leak: Immediate Steps and the Emergency Number
The emergency gas leak number is 0800 111 999; call from a safe place outside.
Avoid ignition sources
Do not smoke, light flames or operate electrical switches. This includes switching lights or appliances off.
Ventilate only if safe while leaving
Open accessible doors and windows without delaying your exit. Do not go through the building opening every window.
Turn off gas only if safely accessible
Use the emergency control valve at the meter only if you know how and can reach it safely. Do not enter a cellar or basement to reach a meter.
Leave and call immediately
Get outside to a safe place and call 0800 111 999. Follow the call handler’s instructions.
Wait for clearance
Remain outside until the emergency engineer says you may return. A fading smell does not establish safety. These precautions follow official gas emergency guidance.
Leaving and calling must not wait for ventilation or turning off the supply. If you are already outside, stay there.
Do not return inside to finish a step, use your phone indoors, reset the boiler or investigate an appliance.
Medical help: For suspected carbon monoxide symptoms, get fresh air and call NHS 111, or 999 for serious symptoms. Do not delay medical help while reporting the gas emergency.
Gas appliance investigation and repair belong to a suitably qualified Gas Safe registered engineer.
What Does a Gas Leak Smell Like?
A domestic natural gas leak can smell sulphurous, often described as rotten eggs, because a warning odour is added to the gas. Recognising a possible warning is enough to act; it does not tell you where gas is escaping or how severe the problem is.
A faint or unfamiliar smell still needs the emergency response. Do not move between rooms or sniff around appliances to find where it is strongest. Carbon monoxide is a separate hazard and has no smell, so your sense of smell cannot rule it out.
If you suspect escaping gas, leave and call 0800 111 999 from a safe place outside.
Symptoms of a Gas Leak: Warning Signs and Medical Help
Possible symptoms of gas exposure need medical attention; a smell or suspected leak needs an emergency report even when nobody feels ill.
- Suspected escaping gas: A gas-like smell is a warning to leave and report the suspected escape. You do not need to identify its source.
- Possible carbon monoxide exposure: Headache, dizziness and nausea can occur with CO exposure, although these symptoms have other causes too. CO has no smell. Treat a sounding CO alarm as a warning requiring immediate action.
For suspected CO exposure, get outside into fresh air. Call NHS 111 for suspected symptoms, or 999 for serious symptoms such as breathing difficulty, sudden confusion, collapse or chest pain. Report a suspected gas-appliance source to 0800 111 999 without delaying medical help. This follows NHS carbon monoxide advice.
Once immediate action has been taken, read more about carbon monoxide symptoms.
How Do You Check for a Gas Leak Safely?
If you suspect a gas leak, do not try to confirm it yourself; leave and report it to the emergency service.
Noticing a warning is enough. Technical investigation requires an engineer with appropriate equipment and qualifications.
- Information already noticed: Tell the call handler where you noticed the smell, when you first noticed it and whether anyone feels unwell. Use information you already have; do not return for photographs or meter readings.
- Investigation for the engineer: Locating an escape, assessing appliances and carrying out gas tightness testing are professional tasks. Tightness testing assesses whether gas escapes from the installation.
Never open the boiler casing, loosen gas joints, apply leak-detection spray or use a flame to test for leaks. Never work on gas yourself. Do not operate appliances or reset the boiler to reproduce a fault. The boiler’s water-pressure gauge cannot establish whether gas pipework is sound.
What Happens After You Report a Gas Leak?
The emergency service assesses the suspected leak and makes the situation safe; your supply may remain off until further work is completed.
Report
The call handler takes details and gives instructions. Explain the location, observations already made and any access difficulties or vulnerable occupants. Do not return inside to gather information.
Make safe
The emergency engineer investigates and explains the findings. Making safe may involve isolating the supply; it does not necessarily complete an appliance or internal pipework repair.
Follow the engineer’s repair instructions
Keep any attendance summary or warning notice for the repair engineer. Internal faults may require a separate Gas Safe registered engineer, as explained in the emergency visit guidance.
If you rent, notify your landlord or managing agent after reporting the emergency. Do not restore the gas supply yourself or assume an isolated appliance is ready to use.
Boiler repair, servicing and gas work
Arrange Gas Leak Repair in London After the Supply Is Made Safe
Only after the National Gas Emergency Service has made the supply safe should you arrange any required internal gas pipework or appliance repair.
All Service 4 U provides gas leak repair in London, including internal leak tracing, repair and subsequent testing. Our Gas Safe registered engineers cover domestic natural gas pipework and appliances, including boilers, cookers and gas fires. Our business registration is 648977.
Have the emergency engineer’s findings or notice available if already accessible. Our 24/7 phone line is available to discuss the required work.
Discuss repair after the supply is made safe: 020 3740 6785
020 3740 6785
Frequently Asked Questions
What Should I Do if I Smell Gas Outside My House?
Move to a safe place away from the suspected escape and call 0800 111 999. Report the street or location you already know and follow the call handler’s instructions. Do not approach to locate the leak, light a flame or assume somebody else has reported it. You do not need to identify the pipe, meter or property involved before calling.
Can Gas Leak From a Radiator?
A conventional wet central-heating radiator circulates heated water, as described in radiator manufacturer guidance, but a gas-like smell nearby still needs the emergency response. The radiator’s water circuit is separate from the appliance’s gas supply. Where you notice a smell does not identify its source. Do not bleed the radiator to investigate; leave and call 0800 111 999 from a safe place.
Will a Carbon Monoxide Alarm Detect a Natural Gas Leak?
A CO-only alarm detects carbon monoxide; it must not be relied on to rule out a natural gas leak. A silent alarm does not make a gas smell safe to ignore. If a CO alarm sounds, get outside into fresh air and report the suspected hazard, even without a smell. Seek medical help for suspected exposure symptoms rather than silencing the alarm and waiting.
Can a Gas Leak Kill You in Your Sleep?
Yes, a gas leak can be life-threatening, so do not go to sleep in a property where a leak is suspected. Escaping natural gas presents fire and explosion hazards. Odourless carbon monoxide is another potentially fatal hazard. Opening a window does not make staying overnight safe. Leave, call 0800 111 999 from outside and wait for the emergency engineer’s clearance before returning.
My Boiler Has Been Labelled Unsafe: Can I Use It Again?
Do not use an appliance labelled unsafe until the required work and safety checks are complete and a suitably qualified Gas Safe registered engineer confirms it can be used. Follow the warning notice, keep the appliance off and retain the notice for the repair engineer. An unsafe finding does not automatically mean replacement is necessary. HSE guidance confirms that unsafe appliances must remain unused.
Still have a question or need urgent assistance? Call 020 3740 6785, tell us what has happened and we will tell you what happens next.