A gas leak in a Sydney home or commercial premises is a genuine emergency. Natural gas is odourless in its natural state, which is why a chemical odorant (mercaptan) is added to give it that distinctive rotten-egg smell. If you can smell gas, you need to act immediately.
This guide covers the immediate steps to take if you suspect a gas leak, how licensed plumbers detect and pinpoint leaks, what the repair process involves, the warning signs that often appear before a leak becomes obvious, and the costs you should expect.
What to Do Immediately If You Suspect a Gas Leak?
Do not wait, and do not try to find the source yourself. Gas leaks can ignite from a single spark — a light switch, a phone, a doorbell, or static electricity. Take these steps in order:
1. Do not touch any electrical switches. Do not turn lights on or off. Do not plug anything in or unplug anything.
2. Extinguish all naked flames. Do not use lighters or matches. If you are cooking, stop. Do not use the oven.
3. Turn off the gas at the meter. Your gas meter is typically located on the exterior of the property. Turn the valve to the off position (perpendicular to the pipe). If you cannot safely reach it, leave it.
4. Evacuate the property. Get everyone — including pets — outside. Leave doors open as you go to ventilate the space if it is safe to do so without touching switches.
5. Call from outside. Once outside, call a licensed emergency gas plumber. Do not re-enter the property until the leak has been located, repaired, and the system has been pressure-tested and cleared.
6. Contact your gas retailer if the emergency plumber is delayed. Jemena Gas Networks (for NSW network faults) can be reached on 131 909. For supply emergencies, your gas retailer (Origin, AGL, EnergyAustralia) also has emergency lines.
Do not attempt to locate the leak yourself using a flame. This is how gas explosions occur.
Warning Signs of a Gas Leak Before It Becomes Obvious!
Not all gas leaks are immediately detectable by smell. Some small or slow leaks present with subtler signs that are often missed or attributed to other causes:
Smell: The most obvious sign. A persistent rotten egg or sulphur smell, even faint, in or around the property. Do not dismiss a faint gas smell as coming from somewhere else.
Hissing sounds: A continuous hissing or whistling sound near a gas appliance, flexible connector, or pipe — particularly when the appliance is off — can indicate gas escaping under pressure.
Dead or yellowing vegetation: If a section of garden or lawn above an underground gas line is unexpectedly dying while surrounding plants are healthy, a slow underground leak may be feeding into the soil and displacing oxygen at the roots.
Bubbling in puddles or wet soil: Gas escaping from an underground pipe into saturated soil will cause visible bubbling in nearby puddles or wet ground after rain.
Higher-than-normal gas bills: An unexplained increase in gas consumption without a change in usage habits can indicate an undetected leak on the supply side of the meter.
Appliance pilot light behaviour: Pilot lights that repeatedly go out, burn an unusual orange or red colour instead of blue, or are difficult to keep lit can indicate issues with the gas supply or combustion quality linked to a nearby leak.
Physical symptoms in occupants: Headaches, dizziness, nausea, fatigue, and difficulty breathing — particularly if symptoms improve when people leave the property — can indicate low-level gas exposure from a slow leak or incomplete combustion.
How Licensed Plumbers Detect Gas Leaks?
Locating a gas leak requires specialist equipment and a methodical approach. Here is how we, as a local plumber in Sydney, work on professional gas leak detection:
Electronic gas detection equipment: Licensed gas plumbers use calibrated gas detectors and sniffers that can detect gas concentrations far below the range a human nose can register. This equipment is moved along pipes, around appliance connections, and near potential leak points to identify gas in the atmosphere.
Pressure testing the gas line: The gas supply is isolated at the meter, and the internal pipework is pressurised with an inert gas (typically nitrogen). The plumber monitors for pressure decay over a set period. A pressure drop confirms a leak exists somewhere in the system. The rate of drop gives an indication of the leak size.
Bubble testing: Approved leak detection solution (similar to soapy water but formulated for gas use) is applied to accessible fittings, valves, and connections. Bubbling at any point confirms the leak location. This method is used alongside electronic detection for visible pipework.
Thermal imaging: For concealed gas pipes running inside walls or under floors, thermal imaging cameras can identify temperature anomalies consistent with gas escaping from a pipe, narrowing the search area before any opening-up work is required.
CCTV and borescope inspection: For embedded or enclosed pipework, borescope cameras can be used to visually inspect without full exposure.
What Does Gas Leak Repair Involve?
Once the leak is located, the repair approach depends on the pipe type, location, and severity:
- Faulty flexible hose or bayonet fitting: Replacement of the fitting. This is the most common source of gas leaks at appliance connections and is resolved quickly.
- Leaking compression or push-fit joint: Joint replacement or remaking. Accessible pipe joints that have corroded or been disturbed can be replaced with correct fittings.
- Corroded or damaged copper pipe section: Section replacement. A corroded section of copper gas pipe is cut out and replaced with new copper and correctly rated fittings.
- Underground pipe leak: Excavation to expose and repair the damaged section, or in some cases pipe relining for the gas service line.
After any repair, the gas plumber must pressure test the repaired section and the full gas system to confirm no further leaks exist before reconnecting gas supply and relighting appliances. A Certificate of Compliance is issued for the work.
What Does Gas Leak Detection and Repair Cost in Sydney?
- Emergency callout and initial detection (after-hours): $200 to $400
- Standard callout and leak detection: $150 to $250
- Flexible hose or bayonet replacement: $150 to $350
- Copper pipe section repair: $300 to $600
- Underground gas pipe repair: $600 to $2,000+, depending on depth and access
All Day Plumbing’s gas plumbers are licensed under NSW Fair Trading for gas work and available 24/7 for gas leak emergencies across Sydney. We carry gas detection equipment on every van and provide pressure testing and compliance certificates with every gas repair.
If you suspect a gas leak, do not delay. Visit our gas services Sydney or call 1300 071 280 immediately.
Frequently Asked Questions
Q: Can I stay in my house while a gas leak is being investigated?
No. Until the leak has been located and repaired, and the plumber has pressure-tested and cleared the system, you should not remain inside the property. Gas can accumulate in enclosed spaces to concentrations well above what the nose can detect, and ignition can occur from any electrical source. Evacuation is not an overreaction — it is the correct response. Once the leak has been repaired and tested, the plumber will advise when it is safe to re-enter and will relight all appliances.
Q: How do I tell the difference between a gas smell from my neighbour’s barbecue and an actual leak in my property?
An external gas smell from a neighbour’s BBQ or a temporary source will typically dissipate within a short time and be directional — stronger when facing a particular direction outdoors. An internal leak will produce a smell that is consistent or intensifying indoors, present across multiple areas of the property, and persistent even after ventilation. If the smell is inside, do not wait to investigate the source. Treat it as a leak until a licensed plumber confirms otherwise. The consequence of being wrong is too serious.
Q: What causes gas leaks in Sydney homes?
The most common causes are deteriorated or damaged flexible gas hoses behind appliances (cooktops, ovens, dryers), corroded bayonet fittings, loose or incorrectly fitted connections following DIY or unlicensed appliance installation, and aged copper pipework that has developed pinhole corrosion. Underground gas service pipes can also develop leaks over time due to ground movement, corrosion, or accidental damage from digging. Properties with older copper gas pipework that has never been inspected should arrange a gas system check as a precautionary measure.
Q: Do I need a compliance certificate after a gas repair?
Yes. In NSW, any gas fitting work must be completed by a licensed gas plumber, and a Certificate of Compliance must be issued for the work. This certificate records what was done, confirms it meets the relevant Australian Standards, and is your legal documentation that the repair is compliant. You should keep this document with your property records. If the work is not certified, your home insurer may refuse a related claim, and the repair may fail a compliance check during a property sale or building inspection.
Q: Is a faint gas smell always a leak, or can it be from normal appliance operation?
A properly functioning gas appliance should not produce a gas smell during operation. A brief faint smell when a pilot re-ignites or immediately after lighting a burner can occasionally occur, but it should dissipate within seconds. Any persistent, recurring, or intensifying gas odour — even faint — should be treated as a potential leak. There is no safe level of ongoing gas smell inside a property. Call a licensed gas plumber to inspect the system. The cost of a callout is trivial compared to the consequences of an undetected leak.