Avoid wastewater overflows

What you need to know to stay safe

Though we do our best to stop wastewater overflows before they happen, we can’t always prevent them. Please stay clear of the area and keep yourself safe. Until the wastewater blockage is cleared and the area cleaned up, any overflow poses a risk to the community and the environment. So, if you see a wastewater overflow, please report it.


When you see a sign like this, you know to avoid the area.

Do what our warning signs say

Stay clear of wastewater overflows by obeying our warning signs. It's the most important thing you can do to stay safe.

  • Stay away from areas that are obviously affected by wastewater overflow.
  • Don’t swim or go fishing in an affected waterway.
  • Don’t drink the water from an affected waterway.
  • Pay special attention to children and pets.
  • Keep away from machinery, hosing and other equipment we’re using to clean up.
  • Keep away from overflowing access chambers or maintenance holes.

Understand why overflows happen 

Wastewater, or sewage, comes from our sinks, showers and toilets. It is transported through our sewerage pipes for treatment. Wastewater overflows happen when something is in the pipe to cause wastewater blockages. There are 3 common causes:

  • tree roots that find their way into the pipes
  • foreign matter like wet wipes, facial tissues and hygiene products flushed in toilets (anything other than pee, poo and paper), and fats, oils and grease poured into sinks 
  • stormwater that overloads the wastewater network during heavy rain.

The blockage prevents the flow of wastewater, which backs up and can overflow out of a maintenance hole. This can occur anywhere there are wastewater pipes: in bushland, in waterways, in a park, on the street or in your own backyard.

Heavy rain is a common reason for sewage overflows.

One Sydney resident reported a $16,000 plumbing bill to repair the sewer pipes at their home. The blockage was caused by flushing wet wipes.


Stay outside barricades, well away from overflows, vehicles and heavy equipment.

Be aware of the risks

It’s important to avoid areas impacted by a sewage overflow and to keep children and pets away from them. Here's why:

  • Sewage contains harmful microorganisms such as bacteria, viruses and protozoa. These can cause illnesses like gastroenteritis if you have direct contact with sewage or surfaces contaminated by sewage. 
  • There may be additional danger from heavy equipment and moving vehicles while we do essential repairs.

Sewage that overflows to the environment can also harm sensitive species of flora and fauna. 


We'll let you know when it's safe

You can be sure the area is safe when we remove our signs and barricades.

We use NATA-accredited labs to sample and test waterways. We test throughout the clean-up, and we continue cleaning until the lab results prove that the site has been effectively cleaned. This can take longer in bushland or natural areas. Our clean-up efforts are regulated by the NSW Environmental Protection Authority (EPA) and NSW Health.

Once we’ve physically cleaned the site, and contaminated surfaces are dry and exposed to sunlight, dangerous levels of microorganisms will be gone. The area will be safe to enjoy again.

When our warning signs are gone, you'll know it's safe.


Our process to manage wastewater overflows

The process we follow to manage wastewater overflow incidents is agreed by regulators:

1  The sewage overflow is reported to Sydney Water.

2  A technician goes to the site to verify sewage overflow and assess the impact on both community safety and the environment.

3  We install containment immediately to stop the overflow from travelling further. We also put up signs and barricades to keep the community informed and safe.

4  The choke crew clears the blockage in the pipe using a high-pressure water jetter.

5  The clean-up crew removes all sewage solids and liquids. It then cleans up the impacted area.

6  Signs and barricades won't be removed until we've completed important checks. The clean-up leader walks the site to verify the clean-up is complete. Then an environmental specialist takes water samples for laboratory assessment – their lab sample confirms the site is back to its pre-overflow condition. 

7  The wastewater overflow is resolved and the site is back to normal.