Start here
If you suspect gas, leave the area and call the gas distributor from a safe location before checking drains. Once gas is ruled out, a smell at one little-used fixture may be a dry trap; recurring odours or several affected drains need a wider plumbing check.
First, rule out a suspected gas leak
Do not assume a rotten-egg smell is coming from the drain. If you suspect gas, leave the area and do not use switches, flames or your phone nearby. From a safe location, call your gas distributor; Jemena’s gas emergency line is 131 909. Call 000 if there is an immediate danger. Only investigate drain odours once a gas concern has been addressed.
Where is the smell coming from?
| What to consider | Useful next step |
|---|---|
| One rarely used fixture | Check whether the trap has water and whether visible debris needs cleaning. |
| Several fixtures or recurring odours | Arrange assessment of drainage, traps and ventilation. |
| Wastewater backs up | Stop using affected fixtures and seek prompt plumbing help. |
For the work involved, see our blocked-drain service and cost guide.
Start with One Drain or Several
A drain smell can come from a dry trap, material around a stopper, a slow line, a damaged connection or a venting problem. Check whether the smell is limited to one fixture and whether the water still drains normally.
Several smelly or gurgling fixtures can point to a shared drainage issue. Wastewater backup needs urgent attention.
A Dry Trap
The water held in a trap blocks drain gases from entering the room. In a little-used fixture, that water can reduce over time.
Run water briefly in a guest basin, shower, laundry tub or floor waste and check whether the odour improves. If it returns quickly, the trap, connection or venting may need inspection.
Buildup Around Accessible Parts
Hair, soap, food and grime can collect around a removable stopper, strainer or overflow opening. Clean only parts designed for normal user access with warm soapy water.
Do not pour boiling water or corrosive cleaner into unknown pipework. Do not mix cleaning products.
Slow or Shared Drainage
Odour with slow drainage, gurgling or a changing toilet water level can indicate restricted flow or venting. Note which fixtures interact. For example, a toilet that gurgles when another drain runs points beyond surface buildup at one waste.
For an apartment or strata property, find out whether neighbouring lots or common areas are also affected before the inspection is arranged.
What an Inspection May Include
The plumber may check the fixture, trap, branch line, venting and accessible sewer. A camera can help where the line is accessible and the symptoms point to a recurring or structural drain problem.
High-pressure water jetting may suit some grease, scale or debris blockages, but the method and pressure must suit the pipe condition. Pipe relining is only considered where inspection confirms suitable pipe damage.
Habits That Reduce Drain Buildup
- Keep strainers clear of hair and food
- Put grease and oil in the bin rather than the sink
- Flush only toilet paper and human waste
- Run water in little-used fixtures periodically
- Keep accessible outdoor grates clear of leaves
- Base any maintenance interval on the actual line history and inspection findings
What to Send with an Enquiry
Describe the affected drains, the type of smell, whether water is slow or backing up, when the problem began and whether rain or another fixture changes it.
See blocked-drain services for recurring problems. Use the 24/7 phone contact if sewage is escaping.
Call 0404 939 121 for an urgent drainage problem, or send the symptoms and property details online.
About the author
Panther Plumbing Group
Family-owned plumbing repairs, maintenance and installations across Sydney. We assess the job, explain the options and discuss the scope and cost before work proceeds.
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