Gas leak warning signs every Australian homeowner should know

The clearest examples of gas leak warning signs are a rotten-egg smell, a hissing sound near pipes or appliances, dead or yellowing vegetation over buried lines, continuous bubbling in puddles, an unusual yellow or orange flame on a burner, and physical symptoms such as headaches, dizziness, or nausea appearing in multiple people or pets. If you notice any of these, the single most important action is to get everyone out of the building immediately. Then call a licenced gas fitter or emergency services if there is any risk of fire or explosion.

Emergency checklist — scan this first:

• Get all people and pets out of the building
• Leave doors and windows open as you go if it is safe to do so
• Do not touch any electrical switches, including lights
• Do not use a mobile phone indoors
• Do not light a match, cigarette, or any open flame
• Turn off the gas at the meter only if you can reach it safely from outside or on your way out
• Once outside and clear of the building, call 000 if there is fire, explosion, or an uncontrolled leak
• Otherwise, call a licenced gas fitter or your gas distributor

Key takeaways

The single most important thing to know is this: any credible gas leak warning sign, including a faint or intermittent rotten-egg smell, demands immediate action, not investigation.

Table of Contents

• What are the main examples of gas leak warning signs at home?
• How can you check for a gas leak safely at home?
• What to do right now if you smell gas in your home
• When should you call 000, your gas distributor, or a licenced gas fitter?
• How can you reduce the risk of gas leaks at home?
• What does a licenced gas fitter actually do when they attend a gas leak?
• Why early recognition matters more than most homeowners realise
• Reactive Plumbing & Electrical provides 24/7 licenced gas fitter support
• Sources
• FAQ

What are the main examples of gas leak warning signs at home?

The most reliable warning sign of a gas leak is a smell like rotten eggs or sulphur. Gas suppliers add a chemical called mercaptan to otherwise odourless natural gas and LPG precisely so that leaks are detectable by smell. That odour can travel well beyond the immediate leak point, so if you catch a whiff outside near a neighbour’s property or along a footpath, it still warrants a call to the gas distributor. Energy Safe Victoria’s natural gas hazards guide confirms that odour from distribution network leaks can be noticeable at a distance from the source.

Sounds you should not ignore

A hissing or whistling noise near a gas pipe, appliance connection, or buried line is a strong auditory clue. The sound is caused by pressurised gas escaping through a gap, and it can be faint enough to miss unless you listen deliberately. If your hot water system, heater, or cooktop is making a sound it did not make before, treat it as a potential gas leak symptom until a professional rules it out.

Visual and environmental clues around your property

Some of the most overlooked warning signs of a gas leak are outdoors. Look for:

• Dead or discoloured vegetation in a patch above where buried gas lines run, particularly if surrounding plants are healthy
• Continuous bubbling in a puddle, pond, or wet soil near outdoor gas infrastructure
• Dust or soil being blown from a small hole in the ground with no obvious cause
• Shimmering air or a vapour cloud near a pipe or fitting on a still day
• Unusual flame colour on a gas burner — a healthy flame is blue; a yellow or orange flame suggests incomplete combustion, which can indicate a supply or appliance fault

Pilot lights that repeatedly go out and unexplained spikes in your gas bill are household clues worth noting too. Neither is definitive on its own, but either combined with a smell or sound should prompt a professional inspection.

Physical symptoms in people and pets

Natural gas and LPG exposure can cause headaches, dizziness, nausea, fatigue, and shortness of breath. In high concentrations, fuel gas displaces oxygen and can cause unconsciousness. If multiple household members or pets develop these symptoms at the same time, particularly indoors, gas exposure is a serious possibility even when no smell is obvious. Pets, being lower to the ground, may show symptoms earlier than adults, which matters especially for LPG users: LPG is heavier than air and pools in low spots such as subfloor spaces, drains, and floor-level areas, rather than rising and dispersing the way natural gas (methane) does.

Pro Tip: RACV’s gas safety guidance emphasises that faint or intermittent odours should never be dismissed. A smell that comes and goes is not a sign the problem has resolved — it often means the leak is small but persistent.

How can you check for a gas leak safely at home?

There are a handful of checks you can do yourself without professional tools, but the boundaries of safe DIY are narrow. Here is what you can do, in order:

1. Listen near appliances, visible pipe connections, and the gas meter for any hissing or unusual sound.
2. Look at burner flames on your cooktop or heater. A blue flame is normal; yellow or orange means something is wrong.
3. Check visible fittings on accessible connections such as BBQ hose joints or regulator connections using a soapy-water test (see below).
4. Smell systematically, moving from room to room, and note whether the odour is stronger near any particular appliance or fitting.
5. Check your gas detector if you have one installed, and note any alarm or elevated reading.

The soapy-water test: what it can and cannot do

Mix a small amount of dishwashing liquid with water and brush or spray it onto exposed, accessible fittings such as a BBQ hose connection or a regulator joint. Bubbles forming at a joint confirm gas is escaping at that point. This method is useful for visible connections, but it tells you nothing about hidden pipework inside walls, underground lines, or any connection you cannot physically reach and coat with solution.

Warning: Soapy-water testing is only appropriate for accessible, above-ground fittings. Never use it to search for leaks in buried lines, inside wall cavities, or under flooring. If you suspect a leak in a hidden or underground section, stop the search and call a licenced gas fitter. Avoid soaps containing ammonia, as some formulations can corrode brass fittings and create a new leak point.

Gas detectors and their limits

A fixed or portable gas detector adds a useful layer of protection, particularly for LPG users where pooling in low areas can go unnoticed. Gas detectors respond to combustible gas concentrations and will alarm before levels reach a dangerous threshold. They are not a substitute for a professional inspection, and they will not locate the source of a leak. Carbon monoxide (CO) alarms serve a different purpose: they detect CO from incomplete combustion, not the fuel gas itself. Both types are worth having, but neither replaces a licenced check.

What you must not do:

• Do not use a naked flame to search for a leak
• Do not switch electrical items on or off, including lights and fans
• Do not use a phone indoors if you suspect a significant leak
• Do not attempt to locate or repair hidden or underground leaks yourself
• Do not light a cigarette or use any ignition source inside or near the building

What to do right now if you smell gas in your home

Act immediately. Do not wait to confirm the smell or investigate further indoors. The SA Government’s gas safety guidance is clear: go outside, open doors and windows as you leave, extinguish any open flames, and do not use electrical switches or phones inside.

1. Get everyone out — people and pets, immediately.
2. Open doors and windows as you move through the building, if it is safe to do so without delay.
3. Extinguish any open flames such as candles or gas cooktops already alight, but only if you can do so without touching electrical switches.
4. Turn off the gas at the meter if you can reach it safely on your way out or from outside. The meter is usually located on an external wall or in a side passage.
5. Move well clear of the building before using any phone or device.
6. Call 000 if there is fire, an explosion, an uncontrolled leak, or anyone is injured or unconscious.
7. Call your gas distributor or a licenced gas fitter for a suspected leak that is not yet an emergency — do not re-enter the building until a professional has cleared it.

Do not, under any circumstances:

• Re-enter the building to retrieve belongings
• Use a lift or press any electrical button inside
• Start a car parked in an attached garage
• Assume the smell has gone away and return inside without professional clearance

When should you call 000, your gas distributor, or a licenced gas fitter?

Knowing which number to call saves critical time. The answer depends on what is happening and where the leak is.

Call 000 immediately when:

• There is a fire or explosion, or one seems imminent
• The leak is uncontrolled and cannot be isolated at the meter
• Anyone in the household is injured, unconscious, or struggling to breathe
• You can smell gas strongly and cannot safely evacuate without assistance

Call your gas distributor when:

• The smell or suspected leak is coming from the street, footpath, or the pipe between the street main and your meter
• You notice signs of a leak on public infrastructure or a neighbour’s supply line
• Australian Gas Networks operates the distribution network across much of South Australia, Victoria, Queensland, and New South Wales. Their emergency guidance advises contacting them for infrastructure-side issues, and they can investigate odour complaints from street mains. Your gas bill or the distributor’s website will carry the emergency number for your area.

Call a licenced gas fitter when:

• The suspected leak is on your property, after the meter
• An appliance is faulty, a pilot light keeps going out, or you have had a smell that has now cleared but you want the system checked
• You need any repair, replacement, or new installation on the property-side gas system

All property-side gas work in Australia must be carried out by a licenced gas fitter. The relevant standard is AS/NZS 5601, which covers gas installations in buildings. In Queensland, gas fitters must be registered with the QBCC; other states have equivalent licensing bodies. Always ask to see a licence before work begins.

Have this information ready when you call:

• Your address and the location of the smell or visible sign
• Whether the smell is inside or outside
• Which appliances are affected or near the suspected leak
• Whether anyone has symptoms such as headaches or dizziness
• Whether you have already turned off the gas at the meter

How can you reduce the risk of gas leaks at home?

Prevention is mostly about routine attention. Gas leaks rarely appear without warning; they usually develop from corrosion, wear, or disturbance that a regular check would catch early.

Routine inspection items:

• Check visible pipework for rust, corrosion, or physical damage, particularly after storms, excavation nearby, or any renovation work
• Keep all gas appliances serviced according to the manufacturer’s schedule
• For LPG users, check cylinder connections and hose condition regularly, and store cylinders upright in a ventilated outdoor area away from ignition sources
• Check low-lying areas of your property, including subfloor spaces and drains, for any gas smell, since LPG pools in low spots rather than rising

A sensible maintenance schedule:

1. Annual appliance service by a licenced gas fitter, covering all gas heaters, hot water systems, and cooktops
2. Visual check of visible pipework after any storm, excavation, or ground movement near gas lines
3. Test CO alarms monthly and replace batteries annually; replace the unit every 5–7 years or per the manufacturer’s instructions
4. Post-renovation inspection any time work has been done near gas lines, even if the tradesperson was not a gas fitter

Simple behaviours that reduce ignition risk:

• Never smoke near LPG cylinders or outdoor gas connections
• Do not store flammable materials near gas appliances or meters
• Keep portable gas devices such as camping stoves for outdoor use only, and never operate them in enclosed spaces
• If a gas appliance smells unusual or produces a yellow flame, stop using it and arrange an inspection before turning it back on

Understanding common causes of gas leaks and the detection tools professionals use can also help you have a more informed conversation with your tradesperson when something seems off. Corrosion, joint failure, and physical damage from excavation are among the most frequent causes seen in residential properties.

What does a licenced gas fitter actually do when they attend a gas leak?

A professional does not just sniff around and tighten a fitting. The process is methodical, and understanding it helps you know what to expect and what to ask for.

The first tool a gas fitter reaches for is an electronic combustible gas detector. These instruments can detect gas concentrations far below what the human nose can reliably sense, which means a professional can confirm or rule out a leak even when the smell has dissipated. They scan along pipework, around fittings, and near appliances systematically.

Other methods and tools used:

• Pressure testing: the gas fitter isolates a section of pipework and applies a measured pressure, then monitors for any drop over time. A pressure drop confirms a leak is present somewhere in that section.
• Soapy-water verification: once an area of concern is identified electronically, soapy water confirms the exact fitting or joint that is leaking.
• Acoustic surveys: for buried lines, acoustic equipment can detect the sound of escaping gas through the ground without excavation.
• Tracer gas and excavation: for underground leaks that cannot be pinpointed acoustically, a tracer gas may be introduced and detected at the surface, or targeted excavation may be required.

Common repairs and what follows:

Repairs range from tightening or replacing a fitting to cutting out and replacing a corroded pipe section. After any repair, the fitter will conduct a post-repair pressure test to confirm the system is sound, and in most states they are required to issue a certificate of compliance for the work. Ask for this certificate before they leave.

Pro Tip: Ask your gas fitter two questions before they start: “What test will you use to confirm the leak is fixed?” and “Will I receive a compliance certificate for this work?” A licenced professional will answer both without hesitation. If they cannot, that is a red flag.

For buried line repairs, trenchless relining techniques can sometimes be applied to gas-carrying conduits, avoiding the need to dig up a driveway or garden. Ask whether this is an option for your situation.

Why early recognition matters more than most homeowners realise

We see it regularly: a homeowner notices a faint smell near the hot water system, assumes it is just a brief whiff from the pilot light, and does nothing for weeks. By the time we attend, the fitting has been weeping gas slowly the entire time. Small leaks do not stay small indefinitely. Corrosion progresses, fittings loosen further with thermal cycling, and what started as a barely detectable odour becomes a genuine hazard.

The other misunderstanding we encounter is the belief that a gas leak will always be obvious. It often is not. A leak in a subfloor space or wall cavity may only produce a faint, intermittent smell indoors, particularly if the building has good ventilation. Pets may seem lethargic, or household members may have recurring headaches that get attributed to other causes. The NSW Government’s gas safety guidance is explicit that physical symptoms of gas exposure can appear before the smell becomes strong enough to trigger alarm.

Calling a licenced gas fitter early is not an overreaction. It is the correct response to any credible sign, and it is far less disruptive than the alternative.

Reactive Plumbing & Electrical provides 24/7 licenced gas fitter support

When you need a professional response to a suspected gas leak, Reactive Plumbing & Electrical provides 24/7 emergency gas leak response and licenced gasfitting for homeowners across Sydney, Newcastle, Wollongong, Brisbane, Ipswich, and the Gold Coast.

Our licenced gas fitters handle on-property repairs, appliance servicing, emergency isolation, and post-repair safety checks, all carried out to AS/NZS 5601 and in compliance with state licensing requirements. Whether you have a confirmed leak, a recurring pilot-light fault, or a smell you cannot quite place, we can attend, diagnose, and fix it properly. For broader home safety context, our homeowner’s plumbing guide covers what to expect from professional trades across your property’s systems.

Call us now or book online to have a licenced gas fitter attend your property.

Sources

These are the authoritative Australian sources referenced throughout this article. Consult them directly for official guidance on gas safety procedures and legal requirements in your state.

• Natural gas hazards safety guide
• Gas safety requirements and consumer rights | NSW Government
• Gas leaks and safety | SA Government
• Gas safety at home | Queensland Government
• What to do if you smell gas at home: a step-by-step safety guide | RACV

FAQ

How do I confirm if I have a gas leak?

The most reliable confirmation is a rotten-egg smell combined with a hissing sound near a pipe or appliance, or bubbles forming during a soapy-water test on an accessible fitting. If you suspect a leak but cannot confirm it, evacuate and call a licenced gas fitter — do not stay inside to investigate.

How would I feel if I had a gas leak at home?

Gas exposure can cause headaches, dizziness, nausea, fatigue, and shortness of breath, often affecting multiple household members or pets at the same time. If these symptoms appear together indoors without another obvious cause, treat gas exposure as a possibility and evacuate immediately.

Can a very small gas leak make you sick?

Yes. Even a slow, low-level leak can accumulate in poorly ventilated spaces and cause persistent headaches, fatigue, or nausea over time. LPG users face additional risk because the gas pools at floor level rather than dispersing upward, meaning concentrations can build in enclosed low areas before the smell becomes obvious.

Can a small gas leak go unnoticed?

Easily. A leak in a wall cavity, subfloor space, or buried line may produce only a faint, intermittent odour indoors, particularly in well-ventilated homes. RACV’s guidance stresses that intermittent smells should never be dismissed, as they often indicate a persistent small leak rather than a one-off event. Reactive Plumbing & Electrical can attend and use electronic detection equipment to confirm or rule out a leak that your nose alone cannot pin down.

Recommended

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• What Causes Gas Leaks and The Tools for Checking Gas Leaks
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