When it's more than a smell
If sewage is coming up through a floor waste, a shower or the grate outside, stop using water in the house: no flushing, showers or washing machine. Keep children and pets away from it, wash your hands well after any contact, and call a drain specialist.
How your drains keep smells out
Under every basin, shower, bath and floor waste is a trap: a bend in the pipe that holds a little water. That water is the seal between your rooms and the sewer. When it dries out, or gets sucked out as other water rushes past, sewer air comes straight through.
Drains also need air to flow. That's the job of the vent pipes poking out of the roof. If one is blocked, draining water can pull the seal out of nearby traps, and you'll often hear gurgling as it happens.
Where it smells, and what that often means
| Often means | Try first | |
|---|---|---|
| A floor waste or shower nobody uses | The trap has dried out | Pour a bucket of water into it |
| Bathroom basin | Soap and hair in the trap, or grime in the overflow hole | Clean the plug and overflow, then run hot tap water |
| Kitchen sink | Fat and food coating the pipe | Scrape plates into the bin and flush with hot tap water |
| Around the toilet | A worn seal where the pan meets the floor or the pipe | Look for damp at the base, then call a plumber |
| Outside, near a grate in the ground | The overflow relief gully is dry or the drain is part blocked | Top up the gully and watch whether water rises |
| All through the house, or with gurgling | A cracked or blocked sewer line, or a vent problem | Call a drain specialist |
Simple fixes worth trying
Refill the traps
Run water into every floor waste, spare shower and guest basin. If a room sits unused for weeks, make it a habit.
Clean what you can reach
Lift out the plug and the shower grate and pull out the hair and slime with a gloved hand. A surprising amount of smell lives right there.
Flush with hot tap water
Hot water from the tap helps shift soap and fat. Skip the boiling kettle: it can damage plastic pipes and joints.
Check the gully outside
The overflow relief gully is the grate in the ground near the house that lets a blocked sewer overflow outside instead of inside. Keep its grate clear, keep garden beds and paving from covering it, and top it up with water if it's dry.
Never mix products
Don't pour bleach on top of a drain cleaner, or two drain products together. Some mixes give off toxic fumes. One product, by the label, and air the room.
When the problem is in the sewer line
If the smell is outside, or several fixtures smell and gurgle at once, the fault is often in the pipe that carries everything from the house to the water company's sewer. Cracks, tree roots and partial blockages all let sewer air out. A drain specialist will usually put a camera down the line, a CCTV drain inspection, to see what's going on before quoting.
Who pays for the fix depends on where the fault sits and which water company you're with, and each company puts the line in a different place. Water Corporation in WA, for example, lists the overflow relief gully, the property sewer and the inspection shaft among the parts the owner looks after. Our guide to who owns the sewer pipe quotes each company we've checked.
If the plumber finds the blockage in the water company's pipe, ask them to report it to the company before they leave. Sydney Water, South East Water and City of Gold Coast all tie their refunds to the plumber reporting the blockage, and Gold Coast needs it reported on the day it's found.
What you can handle, and what you can't
You can
- Refill dry traps with water.
- Clean plugs, overflow holes and shower grates.
- Keep the gully grate clear and uncovered.
- Keep fat, wipes and food scraps out of the drains.
- In Queensland, the QBCC's DIY guide includes "cleaning or maintaining a ground-level grate for a trap on a sanitary drain".
Leave to a licensed plumber
- Anything behind a wall or under the floor.
- A worn toilet pan seal or connector.
- Opening the sewer inspection opening and clearing the line.
- Camera inspections and broken pipe repairs.
- Vent pipe problems on the roof.
What we would do
Refill the traps and clean the grates first: a bucket of water sorts out a lot of smells. If the smell is back within days, or it's strongest outside near the gully, stop covering it with sprays and get the line looked at. A camera inspection shows where the fault is before anyone lifts a paver, and a drain specialist can tell you whether it's your pipe or the water company's.