Smelling Gas? What to Do Immediately

January 2026 Mend Your Home Gas Safety

EMERGENCY: If You Smell Gas

If you can smell gas in your home right now, do not use this page. Get everyone out of the property immediately and call the National Gas Emergency Line from outside:

0800 111 999

FREE 24/7 - National Gas Emergency Service

Step-by-Step: What to Do If You Smell Gas

1 DON'T Touch Anything Electrical

Do NOT:

Turn light switches on OR off
Plug in or unplug anything
Use doorbells
Use your mobile phone inside
Smoke or use lighters/matches

Any spark could ignite leaking gas.

2 Open Doors and Windows

Ventilate the property by opening external doors and windows. This helps disperse the gas and reduces explosion risk.

3 Turn Off Gas at the Meter

If you can safely reach it, turn off the gas supply at the meter. The emergency control valve is usually a lever or tap on the pipe leading from the meter - turn it 90° so the handle is across the pipe.

Only do this if you can do so without operating electrical switches.

4 Get Everyone Out

Evacuate all people and pets from the property. Go outside to fresh air immediately.

5 Call the Gas Emergency Line

From outside the property (or a neighbour's), call:

0800 111 999

This is free, 24/7, and will dispatch a Gas Emergency engineer to make the situation safe.

6 Wait Outside

Do not re-enter the property until the Gas Emergency engineer has declared it safe. This could take several hours.

What Does Gas Smell Like?

Natural gas is actually odourless. A strong, unpleasant smell similar to rotten eggs or sulphur is added deliberately so you can detect leaks.

The smell may be:

Strong and obvious near the leak
Faint but persistent in other rooms
Worse in enclosed spaces
More noticeable when the heating is on

Trust Your Nose: Even if the smell is faint, take it seriously. A small leak can become dangerous, and your sense of smell can become desensitised if you're exposed for a while.

Signs of a Gas Leak

Smell

Rotten egg/sulphur smell
Smell near gas appliances
Smell comes and goes with boiler use

Visual Signs

Dead houseplants near appliances
Yellow or orange boiler flame (should be blue)
Soot or black marks around appliances

Sounds

Hissing near gas pipes
Whistling sounds near meter
Roaring or whistling from boiler

Physical Symptoms

Headaches or dizziness
Nausea or breathlessness
Symptoms improve when outside

After the Emergency

Once the Gas Emergency Service has made things safe, you may need a Gas Safe engineer to repair the fault. We can help.

Call: 07960 066300 Contact Us

Common Causes of Gas Leaks

Faulty or Old Appliances

Ageing boilers, cookers, and gas fires can develop leaks in joints and seals. Annual servicing helps identify problems before they become dangerous.

Poorly Fitted Appliances

Appliances not installed by a Gas Safe registered engineer may have unsafe connections. Always check your engineer's Gas Safe ID.

Damaged Gas Pipes

DIY work, building work, or accidental damage can puncture or loosen gas pipes. Even small damage needs professional repair.

Corroded Connections

Over time, pipe joints and connections can corrode, especially in damp areas. This is why annual inspections are important.

Carbon Monoxide: The Silent Killer

Even More Dangerous Than Gas Leaks

Carbon monoxide (CO) is produced by faulty gas appliances that don't burn gas properly. Unlike gas leaks, CO has no smell - you can't detect it without an alarm.

CO Poisoning Symptoms:

Headaches and dizziness
Nausea and vomiting
Tiredness and confusion
Stomach pain
Shortness of breath

If your CO alarm sounds: Get everyone out, open windows, call 0800 111 999, and seek medical advice if anyone has symptoms.

CO Alarms are a Legal Requirement: Landlords must install CO alarms in rooms with fixed combustion appliances. Everyone should have them - they cost around £20 and could save your life.

Preventing Gas Emergencies

Annual Boiler Service

A Gas Safe engineer checks all components, connections, and safety devices annually. This is the best way to prevent gas and CO issues.

Book Service

Gas Safety Certificate

Landlords must have an annual Gas Safety Certificate (CP12) for all rental properties. This is a legal requirement.

CP12 Guide

Safety Checklist

☑️ Annual boiler service by Gas Safe engineer
☑️ Working CO alarm in each room with gas appliance
☑️ Know where your gas meter emergency valve is
☑️ Never block ventilation for gas appliances
☑️ Only use Gas Safe registered engineers (check ID!)
☑️ Gas Safety Certificate if you're a landlord

Important Numbers

Gas Emergency