What Does a Gas Leak Smell Like? Warning Signs You Should Never Ignore

Natural gas and LPG are both colourless and odourless in their natural state. On their own, you would never know they were escaping. That is why gas suppliers add a chemical odourant before the gas reaches your property, and it is the reason most people describe a gas leak the same way.

A gas leak smells like rotten eggs. Some people describe it as sulphur, off cabbage or a sour, chemical smell. If you notice that odour at home or at work, treat it as a gas leak until a professional confirms otherwise.

What to do if you can smell gas

Act on safety first. Do not try to find the source yourself.

Do not use light switches, power points, appliances or your mobile phone inside the building. A small electrical spark is enough to ignite gas.
Do not smoke or use anything with an open flame.
Open doors and windows if you can do so safely on your way out.
Leave the building and move everyone well away.
If it is safe and you know how, turn the gas off at the meter.
Once outside, call ATCO on 13 13 52. This is the Western Australian gas network faults and emergencies line and it operates 24 hours a day.
If life or property is at immediate risk, call 000.

Never attempt to test, tighten or repair gas pipework yourself. In Western Australia this work must be carried out by a licensed gas fitter, and unqualified work is both illegal and dangerous.

Can you have a gas leak without smelling it?

Yes, and this catches people out regularly. There are several reasons a leak can go unnoticed.

Odour fade

The odourant can be absorbed by soil, rust inside older steel pipework or certain building materials. Underground gas leaks in particular often reach the surface with much of the smell filtered out.

You have become used to it

A very slow leak that builds gradually can dull your sense of smell to it, in the same way you stop noticing a scent after a while in a room. Visitors often notice it before residents do.

Reduced sense of smell

Age, illness, hay fever, medication and smoking all affect the ability to detect the odourant. Elderly residents are at higher risk for this reason.

Other warning signs of a gas leak

Because you cannot rely on smell alone, it is worth knowing the other indicators.

A hissing or whistling sound near a gas appliance, meter or pipe run.
A gas bill that has increased with no change in usage. This is one of the most common signs of a slow underground leak on a property’s gas service.
Dead or discoloured patches of grass or plants in a line above where a gas line runs, with no drainage or irrigation explanation.
Yellow or orange appliance flames instead of a crisp blue flame, along with sooty marks around the appliance.
Pilot lights that keep blowing out.
Physical symptoms such as headaches, dizziness, nausea, fatigue or breathing difficulty that improve when you leave the building. If anyone is unwell, get medical help immediately.

Bubbles appearing in wet ground or in puddles above a gas line can also indicate escaping gas underground.

How professionals locate gas leaks

Once the network provider has made the site safe, the next question is exactly where the leak is. On a long underground gas service running beneath paving, a driveway or landscaping, that answer is not obvious.

Specialist leak detection uses methods designed to pinpoint the location without digging first. Tracer gas detection involves introducing a safe, inert gas mixture into the depressurised line and using highly sensitive surface probes to detect where it escapes. Electronic gas detectors and acoustic equipment are used alongside it to confirm the position.

Subtronic Leak Detection is a Western Australian owned business with extensive experience across plumbing, gas and leak detection. Our role is to locate the leak accurately and advise on the next steps. We do not carry out gas fitting or repair work. Your licensed gas fitter then repairs the specific section identified, rather than excavating a long stretch of pipe to find it.

For homeowners, strata managers, property managers and businesses across Perth, Mandurah and Rockingham, that accuracy usually means less excavation, less reinstatement work and a faster return to normal.