The clearest signs of a gas leak in your house are a rotten egg smell near gas appliances or lines, a hissing sound from pipes or fittings, and dead or dying plants along buried gas mains. If you notice any of these, evacuate immediately and call a licensed gas fitter.
Sydney homes use both natural gas through the Jemena mains network and bottled LPG for BBQs, outdoor kitchens, and off-network areas. Hello Plumbing provides licensed gas fitting services across Sydney and the Northern Beaches. This guide covers how to detect a gas leak, what to do in an emergency, and when to call a licensed gas fitter.
What Does a Gas Leak Smell Like?
Natural gas and LPG are both odourless in their natural state. Gas suppliers add a chemical called ethyl mercaptan to give the gas a distinctive rotten egg smell so leaks are detectable. If you notice a faint sulphur smell near your cooktop, gas meter, or hot water system, it may indicate a minor leak at a fitting or connection. A strong, persistent smell with no identifiable source means gas is escaping in larger volumes, and you should evacuate immediately.
Not everyone can detect the smell. People with a reduced sense of smell, sinus congestion, or age-related anosmia may miss it entirely. Jemena, Sydney’s gas distribution network operator, manages over 25,000 km of gas mains across the city. According to NSW Fair Trading, everyone is legally responsible for gas safety in their homes. If you have gas appliances, consider an electronic gas detector as a backup to your nose.
6 Warning Signs of a Gas Leak in Your Home
If you are wondering how can you tell if you have a gas leak, these are the six signs to watch for:
- Rotten egg or sulphur smell. The ethyl mercaptan odorant is your first line of defence. If the smell persists with all gas appliances turned off, treat it as an active leak and evacuate.
- Hissing or blowing sound near gas lines. Pressurised gas escaping through a cracked pipe, loose fitting, or damaged connection creates an audible hiss. Check around your gas meter, bayonet fittings, and LPG regulator connections.
- Dead or dying plants near gas lines. Gas displaces oxygen in soil, killing plant roots. If outdoor plants along your gas main or indoor plants near gas outlets are wilting without explanation, a buried leak may be the cause.
- Unexplained spike in your gas bill. A hidden leak increases consumption without matching your usage habits. If your bill rises significantly with no change in routine, have your system checked.
- Yellow or orange flame on gas appliances. A healthy gas appliance burns blue. A persistent yellow or orange flame signals incomplete combustion and potential carbon monoxide production. Common with ageing cooktops and wall heaters in 1970s to 1980s homes across Dee Why, Balgowlah, and Brookvale.
- Physical symptoms across the household. Headaches, nausea, dizziness, and fatigue affecting multiple household members at the same time can indicate gas exposure. If symptoms of a gas leak in your house improve when you step outside, take it seriously.
How to Check for a Gas Leak at Home
Before calling a professional, there are several ways to check for a gas leak yourself. These methods help confirm a suspected leak and give your gas fitter useful information when they arrive:
Use the Soapy Water Test
Mix dishwashing liquid with water in a spray bottle. Apply it to exposed gas connections, hoses, and fittings, then turn the gas supply on. Bubbles forming at any point indicate gas is escaping. This works well on BBQ bottle connections, gas meter fittings, and appliance hoses. Avoid soaps containing ammonia, as they can damage brass fittings.
Check Your Gas Meter
Turn off every gas appliance in the house. Check the test dial on your gas meter. If it is still moving with everything off, gas is escaping somewhere in your system. This is a reliable way to find a gas leak that is not visible or audible.
Inspect Flame Colour on Every Appliance
Turn on each gas appliance individually and check the flame. Blue means the appliance is burning cleanly. Yellow or orange means incomplete combustion. Red means stop using the appliance immediately. Check your cooktop, gas heaters, and pilot light on your gas hot water system.
Look for Physical Signs Outside
To tell if you have a gas leak outside, check vegetation along the path of your buried gas main. Look for bubbles in puddles or standing water near the meter. Listen for hissing near the point where the gas line enters your house. These signs indicate a leak between the street and your property.
Install an Electronic Gas Leak Detector
Handheld combustible gas detectors are available from hardware stores and pick up gas at concentrations well below what your nose can detect. A separate carbon monoxide detector is also recommended, as CO is odourless. Place CO detectors near bedrooms and rooms with gas heaters. For concealed leaks inside walls or underground, professional leak detection equipment is needed.
What to Do If You Smell Gas in Your Home
If you detect a gas leak inside your house, follow these steps in order. Do not improvise.
- Evacuate everyone immediately. Get all people and pets out of the house. Move to fresh air at least 10 metres from the property. Do not stop to search for the source.
- Do not use electrical switches or devices. Don’t flick light switches on or off. Don’t plug or unplug anything. Any spark can ignite escaped gas.
- Do not light matches, cigarettes, or candles. Extinguish any open flames on your way out.
- Turn off gas at the meter or bottle if safe to do so. For mains gas, turn the valve so the handle sits at a right angle to the pipe. For LPG, close the valve on the bottle. Only do this if the meter or bottle is easily accessible without re-entering the affected area.
- Call Jemena on 131 909 or Triple Zero (000). Jemena is Sydney’s gas distribution network operator, and its emergency line is available 24/7. If you believe there is immediate danger to life, call 000 first.
- Call a licensed gas fitter for property-side repairs. Jemena will assess the network side. Under the Gas and Electricity (Consumer Safety) Act 2017, only a licensed gas fitter can repair gas installations on your property.
What NOT to Do During a Gas Leak
Knowing what to avoid is just as important as knowing what to do. These mistakes can turn a manageable leak into a dangerous situation:
Do Not Search for the Leak Yourself
Your job is to evacuate, not investigate. Lingering in a gas-filled space increases your exposure to both natural gas and potential carbon monoxide. Professional gas fitters carry electronic detection equipment designed to trace leaks safely.
Do Not Use Your Phone Inside the House
Mobile phones and landlines can produce small electrical sparks. Move at least 10 metres from the property before making any calls, including to emergency services.
Do Not Try to Repair a Gas Leak
All gas work in NSW requires a licensed gas fitter. DIY gas repairs are illegal under the Gas and Electricity (Consumer Safety) Act 2017 and carry penalties of up to 25 penalty units for individuals. They also void your home insurance.
Do Not Ignore a Faint Gas Smell
Even a slight rotten egg smell can indicate a slow leak. Gas accumulates in enclosed spaces over time, and what starts as a minor leak can reach dangerous concentrations. If you can smell gas at all, act on it.
What Your Gas Fitter Will Actually Do
In over 10 years of gas fitting work across Sydney, I have found that a structured diagnostic process catches every leak. Here is what to expect when your gas fitter arrives.
- Electronic gas detection sweep. A handheld electronic gas sniffer traces the exact location of the leak. This is far more precise than any DIY method and detects leaks in concealed pipe runs behind walls and under floors.
- Gas pressure test. The fitter pressurises the gas line and monitors the gauge over a set period. A falling reading confirms a leak somewhere in the system.
- Visual inspection of all gas appliances and fittings. Every connection point is checked, including cooktops, ovens, gas heaters, bayonet fittings, and LPG regulators. Older fittings in Northern Beaches homes across Manly, Dee Why, and Narrabeen are a common failure point.
- Repair or replacement of faulty components. Once located, the fitter repairs or replaces the damaged pipe section, fitting, or appliance connection.
- Certificate of compliance issued. According to NSW Fair Trading, a licensed gas fitter must issue a certificate of compliance confirming the work meets AS/NZS 5601 after completing any gas work in NSW. This certificate must be submitted to the relevant authority within 5 business days.
Carbon Monoxide: The Invisible Danger from Gas Leaks
Carbon monoxide is the hidden risk that most homeowners underestimate. Unlike gas leaks, which the added mercaptan odorant makes detectable, CO gives no warning at all.
Why Gas Leaks Can Produce Carbon Monoxide
When a gas appliance does not burn fuel completely, it produces carbon monoxide instead of carbon dioxide. This happens when burners are blocked, flues are cracked, or ventilation is insufficient. A leaking or faulty gas appliance may produce CO even if the gas leak itself is small.
Symptoms of Carbon Monoxide Poisoning
Early symptoms include headaches, nausea, dizziness, and fatigue. Prolonged exposure causes confusion, chest pain, loss of consciousness, and in severe cases, permanent brain injury or death. According to NSW Health, children, elderly people, pregnant women, and those with chronic illnesses are at higher risk.
What to Do If You Suspect CO Poisoning
Turn off the suspected appliance immediately. Open all doors and windows. Get everyone out of the property. Call Triple Zero (000) if anyone is dizzy, faint, or has lost consciousness. For milder symptoms, call the NSW Poisons Information Centre on 13 11 26 for advice.
Installing a Carbon Monoxide Detector
A CO detector is separate from a smoke alarm and specifically measures carbon monoxide levels. NSW Health recommends choosing alarms that meet US (UL2034) or European (EN50291) standards. Place them near bedrooms and in rooms with gas heaters or enclosed gas appliances.
Why Gas Leaks Are More Common in Older Sydney Homes
Sydney’s housing stock spans more than a century, and each era carries specific gas infrastructure risks. Here is what I commonly find by era and location.
- Ageing bayonet gas fittings from the 1970s to 1980s. Bayonet-point gas outlets were standard in homes built during this era. The rubber seals inside these fittings deteriorate with age, creating slow leaks at wall outlets. Common in Dee Why, Balgowlah, and Neutral Bay.
- Corroded copper gas pipes in pre-1990s homes. Copper gas lines develop weakened joints over time. Salt-air exposure in coastal suburbs like Manly, Collaroy, and Narrabeen accelerates corrosion and increases the risk of a gas leak in your home.
- Original gas hot water systems are past their service life. Gas hot water units typically last 10 to 12 years. Systems well past this age have deteriorating gas connections and failing pilot light assemblies. Common across the Northern Beaches.
- Outdated gas ducted heating in Federation and Inter-war homes. Ducted gas heaters in older homes on the Lower North Shore, including Mosman and Cremorne, may have ageing heat exchangers, cracked flues, and worn gas valves that allow gas to escape.
- LPG systems in off-network areas. Some parts of the Northern Beaches and Frenchs Forest sit outside the Jemena mains gas network and rely on bottled LPG. Regulator and hose failures are a common cause of leaks, especially on BBQ and outdoor kitchen connections.
How to Prevent Gas Leaks in Your Home
Most gas leaks are preventable with basic maintenance. At Hello Plumbing, we recommend the following to every homeowner with gas appliances:
Service Gas Appliances Every Two Years
Under Australian Standards, gas heaters should be serviced every two years by a licensed gas fitter. Cooktops, ovens, and gas hot water systems should follow manufacturer guidelines. Regular servicing catches deteriorating seals and connections before they fail.
Replace Ageing Bayonet Gas Fittings
If your home still has bayonet gas outlets from the 1970s to 1980s, have them inspected. A gas fitter can cap unused outlets and replace deteriorating seals. This is especially important in homes with young children or pets who might dislodge fittings.
Check LPG Connections Before Every Use
For BBQ and outdoor LPG connections, run a soapy water test after every cylinder change. Replace gas hoses showing signs of cracking, splitting, or animal damage. Replace regulators and hoses older than five years.
Keep Gas Appliance Areas Ventilated
Gas appliances need adequate airflow to burn cleanly. Blocked vents, sealed rooms, and dust-clogged fans restrict airflow and increase the risk of incomplete combustion and carbon monoxide production.
Know Where Your Gas Shutoff Valve Is
Every household member should know how to turn off the gas in an emergency. For mains gas, the valve is near the meter. For LPG, the valve is on the bottle. Practise locating and turning it before you need to do it under pressure. If you ever need an emergency gas fitter, knowing how to isolate the supply first can prevent a bad situation from getting worse.
One recent Hello Plumbing client, Murray Keiller, shared his experience after a gas hot water issue: “Good communications. Came out quickly and on time. Gave us the options for either a repair to a very elderly gas water heater or to install a new on-demand gas heater. We went for the latter. The installation was hassle-free, and they even arranged for an electrician to come out to connect the heater to the mains. Tidied up after themselves and even disposed of our ancient system. Overall, we were very impressed with the service we experienced and would not hesitate to recommend them.”
That kind of clear communication and thorough service is what you should expect from any gas work on your home.
Areas We Service
Hello Plumbing provides licensed gas fitting services across Sydney, including the Northern Beaches, North Shore, Lower North Shore, Upper North Shore, Inner West, Eastern Suburbs, Western Sydney, and the Hills District. Whether your home has 1970s bayonet fittings in Dee Why or LPG connections in Frenchs Forest, our licensed gas fitters will find and fix the problem.
Get Your Gas System Checked Today
If you suspect a gas leak in your house or your gas appliances haven’t been serviced in over two years, don’t wait for a small problem to become dangerous. Call Hello Plumbing on 1300 303 055 or book online today. Every job comes with:
- Licensed plumbers with current NSW qualifications (Licence No. 480727C)
- Same-day service and 24/7 availability for urgent inspections
- $0 call-out fee when booked online
- Fixed-price quotes with no hidden fees on all recommended repairs
- Lifetime labour warranty on all workmanship
- On-time guarantee, if we’re late, we pay you $100
- 15% pensioner discount on all services, including inspections
- In-house payment plans with no interest and no finance companies
Get your gas system checked today.
Frequently Asked Questions
What does a gas leak smell like?
Gas companies add ethyl mercaptan to naturally odourless gas, giving it a strong rotten egg or sulphur smell. Even a faint smell near gas appliances or lines warrants investigation. Not everyone can detect it, so an electronic gas detector provides a reliable backup.
Can a gas leak make you sick?
Yes. Gas exposure can cause headaches, nausea, dizziness, and fatigue. Faulty gas appliances can also produce carbon monoxide, which is odourless and potentially fatal. If multiple household members feel unwell and symptoms improve outdoors, suspect a gas leak or CO exposure.
What should I do if I smell gas in my house?
Evacuate immediately. Don’t use light switches or phones inside. Turn off gas at the meter or bottle if safe. Once outside, call Jemena on 131 909 or Triple Zero (000). After the immediate danger is handled, call a gas fitter to inspect and repair the property-side installation.
How do I test for a gas leak at home?
Apply soapy water to gas connections and watch for bubbles. Check your gas meter dial with all appliances off. Install a handheld combustible gas detector. For concealed leaks behind walls or underground, a gas fitter with electronic detection equipment is needed.
How much does gas leak detection cost in Sydney?
Professional gas leak detection in Sydney typically costs $150 to $300, depending on the property size and number of appliances. Repair costs vary based on the location and severity of the leak, from a simple fitting replacement to a section of pipe.
Is a small gas leak dangerous?
Yes. Even a small leak allows gas to accumulate in enclosed spaces over time. This creates fire, explosion, and carbon monoxide risks. Any suspected leak, no matter how faint the smell, should be assessed by a licensed gas fitter.
