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What to Do If You Smell Gas in Your House: A Step-by-Step Safety Guide
What to Do If You Smell Gas in Your House: A Step-by-Step Safety Guide, a Prime Plumbing & Gasfitting plain-English guide to what to do if you smell gas in your house for Melbourne homeowners. Below we cover what works, what doesn't, and when to call a licensed plumber.
Quick answer: If you smell gas, the priority is to make the area safe before anything else. Get everyone outside (including pets), don't operate any electrical switches (lights, garage doors, even your phone), turn off the gas at the meter if you can do so safely, open external doors and windows from outside to ventilate, then call 000 for a major leak. Don't go back inside until the area has been declared safe by emergency services or a licensed Type A gasfitter. After the immediate emergency is handled, book a gasfitter to find and repair the leak source, this isn't DIY work in Victoria.
Read this first
If you can smell gas right now and you haven't done anything yet, stop reading and do these six things in order:
- Get everyone outside. Adults, children, pets, out of the building, and stay out.
- Don't operate any electrical switches. Lights, exhaust fans, garage door openers, range hoods. Switching anything on or off can spark.
- Don't use phones or electronic devices inside. Mobile phones produce small electrical sparks when calls connect. Make calls from outside or from a neighbour's house.
- Turn off the gas at the meter if you can reach it from outside without going back into the gas-affected area. The isolation valve is the lever or quarter-turn handle next to the meter, turn it perpendicular to the pipe to shut.
- Open external doors and windows from outside to ventilate the building.
- Call from outside: Victorian gas emergency hotline 000, or 000 if the leak is major or anyone is unwell.
Don't go back inside until emergency services or a licensed gasfitter has declared the area safe. Don't try to find the leak yourself.
The rest of this article is about what happens after the immediate emergency, diagnosis, repair, prevention. Read it once the gas is off and the area is safe.
Why a small spark matters more than you'd think
Natural gas (methane, the main component of mains gas) is flammable in a concentration range of about 5-15% in air. Below 5% the mixture is too lean to ignite; above 15% too rich. It's the range in between that matters.
A meaningful gas leak in a closed room can build to ignition concentration in minutes. Once you're in that range, any spark, a light switch, a fridge compressor cycling on, a garage door motor, a doorbell, the spark from a static electricity discharge, can ignite the air inside the room. The result is rarely a "fireball" in the dramatic sense; it's usually an explosion that pushes walls and windows outward and is followed by fire.
This is why the safety advice is so specific. Don't operate switches: not because the switch itself is special, but because every switch operation is a tiny spark, and you don't know how close to the ignition range the air around you is right now.
The same logic applies to phones (small spark when the call connects), garage door openers (motor brushes), thermostats (cycling switch), and battery-operated devices.
What does a gas leak smell like?
Natural gas itself is odourless. Australian gas distributors add a tracer chemical called mercaptan (or "ethyl mercaptan", a sulphur compound) so leaks can be detected by smell at very low concentrations. The result is the distinctive rotten-egg or sulphur smell most people associate with "gas".
Some leaks smell stronger than others. A small leak at a fitting may produce only a faint background sulphur smell that you notice when you walk into the room. A larger leak, a failed flexible connector, a damaged pipe, can be overwhelming on entry.
Other smells you might notice with leaks:
- Slightly metallic taste at the back of the throat
- Sickly-sweet smell from incomplete combustion at a faulty appliance (incomplete combustion produces carbon monoxide too, see CO section below)
- Faint hissing sound near the leak source
If you smell gas faintly but consistently in one area of the house, usually near an appliance, water heater, or meter, that's still a leak. Don't ignore it because it's faint. Faint leaks become large ones.
How to turn off the gas at the meter
The gas meter is usually located outside the building, against an external wall. The isolation valve is a quarter-turn lever or handle on the pipe immediately next to the meter, on the side closest to the house.
To shut off:
- Find the lever, it'll be in line with the pipe (parallel) when the gas is on
- Rotate it 90 degrees so it's perpendicular to the pipe
- The gas is now off
Some older meters have a screwdriver-slot rather than a lever. Same principle: rotate to perpendicular.
If you can reach the meter from outside without entering the gas-affected area, turn it off. If the meter is inside or in an enclosed cavity that's been ventilated by gas, don't go in to reach it: wait for emergency services.
After the immediate emergency: gas leak repair
Once the area is safe and the make-safe crew has come and gone, the leak still needs to be found and repaired. This is regulated work: only a plumber with a Type A Gasfitter endorsement can do it legally in Victoria.
What the gasfitter will do:
- Confirm gas is off at the meter and verify the area is clear of gas
- Pressure test the gas line to identify which section is leaking
- Locate the specific leak: normally at a fitting, regulator, flexible connector, or appliance
- Replace the failed component with a compliant equivalent
- Pressure test the repaired line to AS/NZS 5601
- Re-commission appliances that were affected
- Lodge a Certificate of Compliance with Energy Safe Victoria within 5 business days
You'll get a written quote first, the work done, and the certificate emailed with the invoice.
Common causes of household gas leaks
Most residential gas leaks we attend are at one of these points:
- Flexible appliance connectors: the rubber/braided hose between the wall point and a cooktop, oven or gas heater. These have a finite life (typically 5-10 years) and can perish, kink, or fail at the crimps.
- Regulator at the meter: wears out over decades; produces a slight smell at the meter itself
- Threaded fittings on rigid pipework: sealant degrades; especially on older galvanised pipework
- Appliance internals: solenoid valves, control valves and pilot assemblies inside ovens, hot water units and gas heaters can fail and leak gas inside the appliance casing
- Damaged underground gas lines: often from garden works, fence posts driven through buried pipe, or settlement at building joints
Service area
Prime Plumbing & Gasfitting services gas leak repairs across Melbourne's eastern, south-eastern, inner-east and bayside suburbs. See all suburbs we service
Book a gas leak repair
After you've handled the immediate emergency (gas off, area safe, 000 called), call 0475 407 670 during business hours or send through the contact form.
- BPC #103414: Building and Plumbing Commission licence
- Type A gasfitting endorsement for gas appliance work, held on the BPC licence
- 4.8 stars on Google
- Certificate of Compliance lodged with ESV within 5 business days
Who to call
For a gas leak in Victoria:
- 000: Energy Safe Victoria's gas emergency hotline. This connects you to your gas distributor's emergency response (Multinet, AusNet, AGN depending on your area). They'll dispatch a make-safe crew to confirm the leak and isolate it. Free of charge.
- 000: for major leaks, fire, injury, or carbon monoxide poisoning symptoms. They'll dispatch fire and ambulance.
The 000 service is for immediate make-safe: they'll come and check the meter, isolate gas if needed, and check for carbon monoxide. They generally don't repair the leak source, they make the area safe and leave. Repair is the homeowner's responsibility, done by a licensed Type A gasfitter.
Once the area is safe, book a gasfitter. We respond to gas-related callouts during business hours and prioritise them. Our gas leak detection service page has more on how the diagnostic process works.
What about carbon monoxide?
Carbon monoxide (CO) is a different risk, often confused with gas leaks. CO is odourless and colourless: you can't smell it. It's produced by incomplete combustion of gas, typically from a poorly-serviced gas heater, a flueless gas appliance, or a flue that's blocked or damaged.
CO symptoms:
- Headache (often the first sign)
- Nausea
- Drowsiness
- Confusion
- Flu-like feelings that improve when you leave the house
If multiple people in the house get the same headache or nausea symptoms at the same time, and the symptoms ease when you go outside, suspect CO. Get out, ventilate, call 000.
CO testing on rental gas heaters is legally required every two years in Victoria following the Vanessa Robinson coronial inquest. The Victorian Building Authority enforces this. If you rent and your gas heater hasn't been CO-tested in two years, ask the agent.
When to call a licensed plumber
The Victorian Building Authority maintains a plumbing licence search so you can verify your gasfitter holds the Type A endorsement before work starts.
Frequently asked questions
Only if the leak is small, you've turned off the gas at the meter, and you've called the make-safe crew. Don't try to wait out a gas leak by ventilation alone, the source is still leaking, and you don't know whether the concentration is rising or falling without a calibrated detector. Get out, call 000, then come back when it's safe.
A mobile phone produces small electrical sparks when the call connects to the network, generally inside the device, but enough to ignite a gas-air mixture in the ignition concentration range. Make the call from outside the house, from a neighbour's, or from your car at the kerb.
Intermittent smells often point to a small leak at a fitting that releases more gas under certain conditions (warm vs cold, pressure spike when the regulator cycles, post-appliance shutdown). Don't ignore it. Book a gasfitter to do a leak detection inspection, small chronic leaks turn into bigger ones over time.
Not necessarily, but it's a symptom worth investigating. A pilot that won't stay lit can mean a faulty thermocouple (cheap fix), a clogged pilot orifice, or a problem with the gas supply pressure. Sometimes a small upstream leak is depriving the pilot of pressure. Get it looked at.
Modern gas ovens have a safety valve that closes when the pilot or ignition is off, so an unlit oven shouldn't leak. Older ovens without flame-failure safety valves can leak if a knob is bumped to ON without ignition. If you have an older oven and you smell gas at the cooktop or oven, that's a possible cause, get it inspected and consider replacement.
Get it serviced by a licensed gasfitter. The Victorian Building Authority recommends servicing gas appliances every 2 years, and gas heater carbon monoxide testing is mandatory every 2 years for rental properties. Servicing covers leak testing, combustion analysis, flue check, and operational performance.
Ask the agent or landlord for the most recent gas safety check and CO test records. The landlord is required to provide them. If the records are old or missing, the property may be non-compliant, Consumer Affairs Victoria can advise on rental gas safety obligations.
How much does a gas leak repair cost?
It depends entirely on where the leak is and what needs replacing:
- Flexible appliance connector replacement: typically $150-$350
- Regulator replacement at meter: typically $250-$550
- Threaded fitting repair on rigid line: typically $200-$500
- Pressure test and certification only (no repair needed): typically $200-$400
- Major repair (multiple fittings, section of pipe, internal appliance work): quoted after diagnosis
We quote in writing first after diagnosing the leak. Repair is rarely the most expensive option, the diagnosis time is commonly most of the visit.
- When did the issue start?
- Is it isolated to one fixture or multiple areas?
- Are there any visible leaks, smells or unusual sounds?
- Have you turned off the relevant isolation valve?
- Gas leak detection Melbourne: pressure testing, leak location, repair
- Gas fitter Melbourne: gas appliance install, service and replacement
- Emergency plumber Melbourne: for urgent plumbing alongside gas issues
