NT Health has started analysing wastewater for early signs of coronavirus, confirming today it is testing samples from 10 wastewater catchments across the Territory for the virus.

The government said testing had already confirmed traces of COVID-19 at a catchment area near the Howard Springs quarantine facility, which health experts said was to be expected.

It was unclear how long the government has been testing the wastewater and why they only announced it via a press release this morning.

Health authorities said the testing will complement existing pathology-based COVID-19 testing for individuals.

It will be initially done for a three-month period across the Darwin and Palmerston region, and include the Howard Springs Quarantine Facility, after which the system will be reviewed.

Acting Chief Health Officer Dr Charles Pain explained in October 2020 that “wastewater testing basically flags to us that there may be a positive in the area or in that catchment area”.

“It doesn’t mean that there is a positive, and it doesn’t mean that they’re active in other words that they’re infectious,” he said at the time.

“It just means that we should then look more closely, do our local inquires, do contact tracing, and do some wider testing and on occasion, for example in southwestern city that it has actually shown up some positives.”

He cited that last year in Western Sydney, there was a positive wastewater case, and then subsequent testing was negative, indicating that there “can be false positives.”

“It’s really just a flag that we should be looking more closely,” he said.

Recent wastewater test results in the NT have detected fragments of coronavirus in the sample taken from the Stow Road pump station that serves as a catchment to the Howard Springs Quarantine Facility.

“It is reassuring to see the detection of COVID-19 in our wastewater from the Howard Springs Quarantine Facility, as this indicates that our system is accurately detecting fragments where we expect them,” Dr Pain said.

Health authorities said there has been no other detections of COVID-19 in wastewater sampling from the other sites.

They said if there’s a detection of Covid-19 fragments in the sewerage network, geographical locations will be flagged which will then warrant an increase in clinical testing to individuals.

“As we continue to sample wastewater, we expect that we may see positive detections in other sites, even if there are no cases in the community, as it is well known that people shed fragments of the virus for months after clinically recovering from COVID-19,” Dr Pain said.

Wastewater samples are being collected from suburban areas and sites that target high volume tourism and event locations such as Mindil Beach and the CBD. Population numbers in each catchment are below 50,000, NT Health data states.

The ten sampling catchments sites in the NT include:

• Ludmilla Sewage Treatment Plant inlet
• Stuart Highway
• Darwin CBD
• Mindil Beach
• Leanyer/Sanderson Sewage Treatment Plant #1 – inlet from Western Area
• Leanyer/Sanderson Sewage Treatment Plant #2 – inlet from Northern Suburbs
• Rocklands Drive Tiwi, isolated to RDH campus
• Palmerston Sewage Treatment Plant inlet
• Bridle/Catalina Road intersection
• Stow Road pump station (Isolated to the Howard Springs Quarantine Facility)