There's a gas smell in the house — what do I do?
This is the one guide on AskFix with no repair steps — deliberately. A gas leak is not a DIY job. Your job is to get out safely and let a professional handle it.
The problem
You smell rotten eggs or a strong sulphur odour near the gas cylinder, cooker or water heater. Sometimes there's a faint hiss, or the flame burns yellow/orange instead of blue, or several people in the house get a headache, dizziness and nausea at the same time — and it clears once you're outside.
Likely causes
An old or cracked gas hose
The rubber hose between the cylinder and the cooker perishes and cracks with heat and age. It's a very common household leak, and it should be replaced every few years — but that replacement is a technician's job, not a rushed one.
A loose regulator or a bad seal
The regulator that clamps onto the cylinder head can sit loose, or the washer inside it can be worn, so gas escapes at the joint itself.
A burner or oven left open with no flame
Sometimes the cause is mundane: a knob was turned and the flame never caught, or a pot boiled over and killed the flame while gas kept flowing. The smell is strong but the source is obvious.
A leak in the mains gas pipework or a failed valve
In homes on piped gas the leak can be in the installation itself. That is strictly work for the gas utility or a licensed technician.
When to call a professional
Always. There is no version of a gas leak where 'I'll just fix it myself' is the right answer. Even if you're sure it's only the hose, that hose gets replaced with the gas shut off and then leak-tested with soapy water by someone who knows what they're doing. And if the smell is strong or you can't tell where it's coming from, don't go back in at all — call the fire brigade from outside and let them enter.
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Why can't I turn on a light to see?
Because a light switch makes a tiny electrical spark inside as it opens and closes. If there's gas in the air, that spark is enough to ignite it. The same goes for the kitchen extractor, a fan, the doorbell, and your phone. Don't switch anything on or off and don't plug anything in — just leave.
Should I cut the power at the main breaker on my way out?
No. Throwing a breaker sparks too. Don't touch the panel. Open a door or window if they're on your way out and it costs you nothing — but the priority is getting outside quickly.
What exactly do I do first?
Kill any open flame you're already standing next to (cigarette, candle, burner), close the cylinder valve if it's within arm's reach and you don't have to cross the room to get to it, open the door, get out, leave the door open behind you, move away from the building — then call emergency services from outside. If reaching the valve is any kind of adventure, skip it and leave.
Who do I call?
Call your local emergency number from outside the building, not from inside it. In Thailand, dial 199 for the fire brigade or 191 for police; elsewhere, use your country's emergency number.
The smell went away on its own — is it safe now?
Not necessarily. The smell fading may mean the ventilation is doing its job — but it may also just mean your nose has adapted to it, which happens fast with household gas. If you're in any doubt, have someone test it with a proper gas detector before you sleep in the house.
Can I use soapy water to find the leak?
That is a genuine test and technicians use it — but only after the area is made safe and ventilated and the gas is shut off, and only by someone who knows what they'll do when they find it. It is not the homeowner's first move while the house is still full of gas.