Signs and Symptoms of a Gas Leak
Know the warning signs — smell, sound, sight and how you feel. If you suspect a leak now: ventilate, turn off the gas, avoid switches and flames, and call 0800 111 999. Then call Gas First on 07927 882561.
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Upfront cost — no obligation Spotting a gas leak early can prevent a fire, an explosion or carbon monoxide poisoning. Some signs are obvious, like the smell of gas; others are easy to miss, such as feeling unwell at home but better when you go out. This page lists the warning signs to look, listen, smell and feel for, and tells you exactly what to do if you suspect a leak. Our Gas Safe registered engineers (587401) detect and repair leaks across East London.
Smell — the most common sign
Natural gas is naturally odourless, so a strong-smelling additive is put in to make leaks noticeable. Most people describe it as ‘rotten eggs’ or sulphur. If you notice that smell — near your boiler, cooker, meter or anywhere in the home — treat it as urgent and do not ignore it, even if it seems faint or comes and goes.
Natural gas is naturally odourless, so a strong-smelling additive is put in to make leaks noticeable.
Sound and sight
Listen for a hissing or whistling sound near a gas appliance, pipe or the meter. Look for a pilot light that keeps blowing out, an unusually lazy yellow or orange flame instead of a crisp blue one, black or sooty marks around an appliance, excessive condensation on windows, or houseplants near a gas line dying for no clear reason. Any of these can point to a leak or poor combustion.
Listen for a hissing or whistling sound near a gas appliance, pipe or the meter.
How you feel — possible carbon monoxide
A gas leak or badly burning appliance can produce carbon monoxide (CO), a gas you cannot see or smell. Warning signs include headaches, dizziness, nausea, tiredness, breathlessness or a feeling of being unwell that eases when you leave the house and returns when you go back in. If several people or pets in the home feel unwell at once, take it seriously — get fresh air immediately and seek medical advice. A working CO alarm is strongly recommended in every home with gas appliances.
A gas leak or badly burning appliance can produce carbon monoxide (CO), a gas you cannot see or smell.
What to do if you suspect a gas leak
Open doors and windows to ventilate. Turn the gas off at the meter control valve if you can reach it safely. Do not switch anything electrical on or off, do not use naked flames, and do not use your phone indoors. Leave the property if the smell is strong. Call the National Gas Emergency Service on 0800 111 999 (free, 24 hours). Once the supply is safe, call Gas First on 07927 882561 and a Gas Safe engineer will locate and repair the leak across East London.
Open doors and windows to ventilate. Turn the gas off at the meter control valve if you can reach it safely.
Frequently Asked Questions
What does a gas leak smell like?
Gas has a distinctive added smell, usually described as rotten eggs or sulphur. If you notice it, treat it as urgent.
What are the physical symptoms of a gas or carbon monoxide leak?
Headaches, dizziness, nausea, tiredness and breathlessness — especially if they ease when you leave the house and return when you go back — can indicate carbon monoxide. Get fresh air and seek medical help.
Can you have a gas leak without smelling it?
Yes. Carbon monoxide is odourless, and a slow leak can be hard to smell. That is why a CO alarm and awareness of the other signs — hissing, sooty marks, feeling unwell — matter.
What should I do first if I think I have a gas leak?
Ventilate, turn off the gas at the meter if safe, avoid switches, flames and phones indoors, leave if the smell is strong, and call 0800 111 999. Then call us to find and repair it.
Do you detect gas leaks across East London?
Yes. Our Gas Safe registered engineers carry out tightness tests and leak detection across East London from our Bow and Dagenham bases, and repair the fault safely.
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