What a blockage looks like
Sydney Water asks you not to ignore these:
- sinks, the bath or the toilet are slow to empty;
- the toilet won’t flush properly, or it has overflowed;
- you hear gurgling from the toilet or a floor drain;
- the drain or gully by your outside tap has overflowed with wastewater.
If an overflow or backed-up wastewater happens only while you are using water on your property, and particularly if only some of your fixtures are affected, Sydney Water says you must get a licensed plumber’s assessment as soon as possible.
Reading the clues
Who pays to clear a blockage depends on where Sydney Water’s pipes connect to the property. Sydney Water gives two sets of clues for working out which side of that line a blockage is on.
| Probably in your private pipes if | Probably in Sydney Water’s pipes if |
|---|---|
| your neighbours aren’t having a blockage | your neighbours have the same problem |
| your drainage isn’t shared with other properties | the overflow is visible beyond your boundary, such as from a maintenance hole on public land |
| there’s no flooding in your local area | there’s widespread flooding in your local area |
| it only overflows when you use water on your property | it overflows continuously while you aren’t using water |
13 20 90Not sure which side it is on? Sydney Water’s line is open 24 hours a day, and it says it will ask some simple questions to help find where the blockage is.
Its report a fault page says to treat it as an emergency if there are overflows on your property even when you aren’t using water.
Where roots meet the line
Sydney Water owns the junction. The property owner is responsible for their connection to Sydney Water’s system, which it calls the point of connection.
That matters for roots. Sydney Water’s repair rules put two jobs on the property owner: clearing tree roots that get into the junction at the point of connection, and fixing damage to that junction from roots or digging.
If clearing roots damages the junction, Sydney Water may repair or replace it, and may do so at no cost; the owner still pays for digging around it so it is fully exposed. If the blockage happened because Sydney Water’s junction failed, its crew has to confirm that first. If it accepts responsibility, it pays to repair the junction and restore the site; it calls this a takeover.
Sydney Water won’t reimburse excavation costs unless one of its authorised representatives approved the dig first.
When the plumber finds it in Sydney Water’s pipe
You can claim reasonable out-of-pocket expenses if you paid a licensed plumber who found a blockage in Sydney Water’s wastewater pipes, as long as the plumber reported it to Sydney Water to investigate. Sydney Water lists what a claim needs:
- a job number, which the plumber gets by ringing Sydney Water, included in the claim;
- all invoices and supporting documents;
- a timesheet or excavation details if the invoice doesn’t describe the work in detail.
Sydney Water says a claim may take up to 8 weeks to process. If overflow from its pipes damaged your property, it says it will arrange a clean-up and repairs to stop the overflow, and give you a Customer Advocate to manage your complaint and support you through the insurance process.
One more case: if your own wastewater pipe has collapsed under a public footpath or road, Sydney Water may fix it at no charge for residential customers, once a licensed plumber confirms there is no way to fix it other than digging up the road or footpath.
Why roots find the pipes
Roots looking for nutrients find their way into small cracks in wastewater pipes. Once inside they keep growing, fill the pipe and slow the flow, until it blocks. On its overflows page, Sydney Water calls roots the most common cause of blockages, and says blockages normally contain a combination of roots, flushed items and fats.
Its advice before planting: know where your pipes are. You can get a sewerage service diagram online through Sydney Water Tap in, and Sydney Water advises against planting trees within 6 metres of wastewater pipes. A local nursery can tell you which trees and roots to expect, and where trees already cause trouble, a plumber can put the pipes on a regular maintenance plan.
| Common name | Botanical name |
|---|---|
| Bottlebrush | Callistemon sp. |
| Gum trees (large) | Eucalyptus sp. |
| Figs (Moreton Bay Fig, Weeping Fig, Rubber Tree) | Ficus sp. |
| Jacaranda | Jacaranda mimosifolia |
| Liquidambar | Liquidambar styraciflua |
| Lilly Pilly | Syzygium sp. |
| Crepe Myrtle | Lagerstroemia sp. |
| Paperbarks | Melaleuca |
| Camphor Laurel | Cinnamomum camphora |
| Bamboo | Bambusa sp. |
| Willows | Salix sp. |
| Apricot, Cherry, Peach, Plum | Prunus sp. |
The list, as Sydney Water gives it, is on its wastewater blockages page under “Avoid planting these trees”.
The gully by the outside tap
The overflow relief gully is a riser on the house drain whose top must sit a set height above the ground (below). Wastewater coming out of the gully near your outside tap is on Sydney Water’s list of blockage signs.
NSW sets how high it sits. Building Commission NSW’s advisory note of June 2026 quotes the plumbing standard: the top of the gully riser must be at least 150 mm below the lowest fixture connected to the drain, and at least 75 mm above the finished ground, unless it is in a path or paving, where it is finished so water can’t pond and get in. The regulator says gullies installed without those clearances can lead to significant property damage in a sewer surcharge or blockage, and asks plumbers to allow for future landscaping and paths that could change the heights.
Staying clear of it
Wastewater contains harmful microorganisms, such as bacteria, viruses and protozoa, that can cause illnesses like gastroenteritis through direct contact with it or with surfaces it has touched. Sydney Water asks people to keep children and pets away from overflows.
For a smell from a floor waste, Sydney Water suggests pouring in a small bucket of water with disinfectant, which tops up the water sitting in the seals and traps. If the smell comes from a problem in your own pipe, you’ll need a plumber.