Wastewater testing

The ACT’s Wastewater Surveillance Program

Fragments of the virus that causes COVID-19 can enter wastewater (sewage) through:

  • an infected person’s faeces
  • when washed off hands and bodies via sinks and showers
  • on used tissues.

Over time, the virus breaks down and small pieces of the virus (called ‘viral fragments’) can enter wastewater through bowls, sinks and drains, and then travel through the sewer network.

While viral fragments may indicate that people within a community currently have COVID-19, people can still shed the virus for several weeks, well beyond their infectious period.

The ACT Wastewater Surveillance Program tests untreated sewage for fragments of SARS-CoV-2 (the virus that causes COVID-19) at six locations across the ACT, covering the whole ACT population.

This program is conducted in collaboration with ICON Water, the NSW Sewage Surveillance Program, and the Australian National University.

Sewage is collected and tested twice a week.

Wastewater (sewage) testing

Sewage testing can give a snapshot of the possible presence of the virus in a local area.

Testing sewage can help provide early warning of possible undetected infections in the community.

Most states and territories in Australia are conducting COVID-19 testing of sewage.

ACT Health uses the information from the Wastewater Surveillance Program, alongside COVID-19 testing results from ACT residents, to help support our COVID-19 response.

Testing raw sewage for virus fragments is a specialised test and cannot be carried out by many laboratories.

Samples collected in the ACT are transported to Sydney to be analysed by NSW Health.

NSW Health works closely with national partners to ensure testing is of the highest standard.

Why might COVID-19 virus be detected in sewage?

There are a number of reasons why the virus that causes COVID-19 might be detected in sewage in the ACT.

ACT residents continue to return to the ACT from overseas. The majority of these residents undertake hotel quarantine in other states/territories.

Some will develop COVID-19 while in hotel quarantine.

Once they have recovered from COVID-19 and are no longer infectious, they are released from isolation and return to the ACT.

These people may continue to shed virus fragments into the sewage  system.

COVID-19 cases may occur in the ACT during periods of hotel quarantine of Australians who are returning home from overseas.

This may lead to detection of the virus in sewage from the wastewater collection site near the quarantine hotel.

In addition, a very small number of returning ACT residents and other international travellers may be given an exemption from hotel quarantine and instead quarantine at home in the ACT.

There have only been a very small number of positive cases in home quarantine over the past several months.

Finally, a positive detection of the virus that causes COVID-19 in sewage may indicate that there is an undetected active case of COVID-19 in the community.

Response to positive COVID-19 testing in wastewater

Any time there is a positive wastewater test for the COVID-19 virus, ACT Health will look at other information, such as where the positive detections have occurred, whether there are current cases in the ACT or whether there are known recovered cases in the area(s), and the concentration - or strength - of the positive sample.

ACT Health will then provide advice on whether increased public health measures are necessary.

ACT Health may encourage increased COVID-19 testing in areas where virus fragments have been detected in wastewater.

This is particularly important if there have not been any known COVID-19 cases in the area recently.

Read more about COVID-19 symptoms and how to get tested on the Symptoms and Getting Tested page.

Everyone in the ACT should continue to practise COVID-safe behaviours such as physical distancing and good hand hygiene.

Safety of ACT drinking water

Drinking water in the ACT is treated before being delivered to your tap and is safe to drink.

The treatment is designed to inactivate (kill) or remove even the toughest microorganisms, including viruses, bacteria, and protozoa.

SARS-CoV-2, the virus that causes COVID-19, is not a difficult virus to inactivate.

No additional or modified treatment is required beyond the current drinking water treatment.

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Acknowledgement of Country

We acknowledge the Traditional Custodians of the ACT, the Ngunnawal people. We acknowledge and respect their continuing culture and the contribution they make to the life of this city and this region.

Last Updated: July 15 2021