Wastewater blockages

What you can do to prevent them

We spend $27 million every year clearing up to 20,000 blockages from our wastewater system. Household waste flushed down toilets or poured into sinks blocks drains and clogs pipes. It's often the reason wastewater backs up and overflows into homes, yards and local waterways.

Signs of a wastewater blockage

Wastewater blockages have a variety of causes. These include tree roots, unflushable items being disposed of in the toilet, oils and fats poured into sinks, and even stormwater overloading our wastewater network during heavy rain. If the signs are ignored, wastewater blockages can create greater problems for you, the community and the environment. If the blocked pipes are on your property, you could be looking at a costly plumbing bill.

You may have a blockage in your pipes if:

  • your sinks, bath or toilet empty slowly
  • your toilet is not flushing properly or has overflowed
  • your toilet or floor drain is making gurgling noises
  • wastewater has overflowed from the drain (or gully) near your outside tap.

If you see a wastewater overflow
Whether it's on your property or in a public place, please call our faults line 13 20 90 24/7 to report it. For your own safety, stay clear of wastewater overflows.

Toilets and wastewater blockages

Blockages from unflushable items cause overflows that are a health and environmental nightmare. Only flush the 3 Ps: pee, poo and toilet paper. Put everything else in the bin.

  • Non-flushable wet wipes contribute to 75% of blockages. Before you flush any type of wet wipe, check it has the 'flushable' icon and ensure it has the Australian standard AS/NZS 5328:2022.
  • Paper towels are designed for superior absorbency and durability. They don't break down like toilet paper, and shouldn't be flushed.
  • Hair doesn't dissolve in water. It floats, and snags easily on other unflushables.
  • Tissues don't break down easily in water. When they're flushed, they easily build up.
  • Cotton buds are made of materials that don't dissolve in water.

Are you a toilet blocker?
Whether it's flushed toys, tissues or non-flushable wet wipes, you're not alone. Find out more from our latest campaign: Toilet Blockers Anonymous.

Fats, oil, grease and wastewater blockages

Never pour fats, oils or grease down the drain. They cool and harden when they hit the water in wastewater pipes. They also combine with unflushable toilet waste to create hard-to-remove fatbergs.

  • Make sure your sinks have a sink strainer fitted to trap food waste. You can add food waste to compost or put it in the garbage bin.
  • Place oily products like food scraps, excess cooking oil, unused milk and other leftovers in sealed containers and put them in the garbage bin.

Trees and wastewater blockages

Tree roots can enter small cracks in wastewater pipes to seek out nutrients. Once there, they continue to grow, taking up space and slowing drainage. This can cause a blockage.

Before you plant trees on your property, know where your pipes are. You can get a sewerage service diagram online at Sydney Water Tap in®. Avoid planting trees within 6 metres of wastewater pipes. Some trees are more likely to cause problems to wastewater pipes. Your local nursery can advise on trees and their root systems.

If existing trees are a problem, ask a plumber to set up a regular maintenance plan for you.

Trees to avoid planting

Botanical name Common name
Acer sp. Maple (mostly large)
Araucaria sp. Norfolk Island Pine
Bambusa sp. Bamboo
Brachychiton acerifolius Illawarra Flame Tree
Callistemon sp. Bottlebrush
Casuarina sp. Casuarinas or She-Oaks (especially River Oak and Swamp Oak)
Celtis sp. Nettle-tree and Hackberry
Chamaecyparis/Cupressus sp. Cedar and Cypress
Cinnamomum camphora Camphor Laurel
 Erythrina sp. Coral tree (large)
 Eucalyptus sp. Gum trees (large)
 Ficus sp. Figs (Moreton Bay Fig, Weeping Fig, Rubber Tree)
 Fraxinus sp. Ashes (large)
 Jacaranda mimosifolia Jacaranda
 Lagerstroemia sp. Crepe Myrtle
 Liquidambar styraciflua Liquidambar
 Lophostemon confertus Brush Box
 Magnolia sp. Magnolias (large)
 Melaleuca Paperbarks
 Metrosideros excelsus New Zealand Christmas Tree
 Morus sp. Mulberry (especially Black Mulberry)
 Murraya paniculate Orange Jasmine
 Nerium oleander Oleander
 Persea americana Avocado
 Phoenix canariensis Canary Island Date Palm
 Pinus sp. Pine
 Platanus sp. Plane trees
 Populus sp. Poplars
 Prunus sp. Apricot, Cherry, Peach, Plum
 Quercus sp. Oaks
 Salix sp. Willows
 Sapium sebiferum Chinese Tallow Tree
Schefflera actinophylla Umbrella Tree
 Schinus molle Pepper Tree
 Syzygium sp. Lilly Pilly
 Ulmus sp. Elms (large)
 Wisteria sp. Wisterias


If the blockage is in our pipes

Sydney Water is responsible for wastewater pipes from our network up to where they connect to your property. The blockage is probably in our pipes if:

  • the overflow is visible beyond your property boundary, such as from a maintenance hole located on public land
  • your neighbours are experiencing the same problem
  • there's widespread flooding in your local area
  • you're experiencing a continuous overflow and you're not currently using water on your property.

Call us on 13 20 90 24/7 to report the issue. We'll send a crew to investigate.

If overflow from our pipes damages your property

We'll arrange a clean-up and carry out any repairs required to stop the overflow. You'll be assigned a Customer Advocate who will case-manage your complaint and support you through the insurance process. They'll also advise what they can do if you're not insured.

You can claim for reasonable out-of-pocket expenses if you're a customer and you've paid a licensed plumber who found a blockage in our wastewater pipes that they reported to us to investigate. To claim, use our wastewater blockage claim form. We'll send confirmation once we receive your claim. It may take up to 8 weeks to process. Before you fill out the claim form, please make sure that:

  • the plumber calls us on 13 20 90 to get a job number – this number needs to be included on the form
  • you have all invoices and supporting documentation ready to attach
  • you provide a timesheet or excavation details if the invoice doesn't give a detailed account of the work completed.

If the blockage is in your private pipes

Property owners are responsible for the private wastewater pipes on their property up to where they connect to our pipes. You'll need to contact a licensed plumber to clear the blockage.

The blockage is probably in your private pipes if:

  • your neighbours aren't experiencing a blockage
  • your drainage isn't shared with other properties
  • there's no flooding in your local area
  • you only experience an overflow when using water on your property.

Not sure if the blockage is in your private pipes or our network?
Call us on 13 20 90 24/7. We'll ask you some simple questions to help identify where the blockage is.

If private wastewater pipes collapse on public land

As a free service to residential customers, we may repair private collapsed wastewater pipes under a public footpath or roadway. A licensed plumber must confirm that the fault can't be repaired without excavating the roadway or footpath. Find out more from our Collapsed Private Services in Public Land Program: Guide for customers. Also, see section 8.6 of the Customer Contract.