The amount of Covid-19 detected in the country's wastewater has been increasing at least 10-fold each week for the past couple of weeks.
File photo. Photo: 123RF
Scientists have been sampling wastewater since 2020; with positive detections of Covid-19 providing an early warning that someone in the community was infected.
The virus was now being picked up in nearly every community.
Institute of Environmental Science and Research (ESR) science leader Dr Brent Gilpin told Morning Report only a month ago almost 75 percent of wastewater testing sites had no virus detectable.
"Two weeks ago it was 50 percent. Now I think we only had two sites and they didn't have a detection last week, but I'm almost certain that this week we'll get a 100 percent across the country."
He says the levels detected in Auckland, Northland and the Bay of Plenty are the highest in the country.
"We look at the viral RNA or the genome and what we have is genome copies, which up until recently have been sort of several 100 per litre of sewage.
"But we're now ... getting up to half a million of these genome copies per litre. Previously if we had 1000 copies we delayed would really get quite excited. Now the levels are really creeping up across the country and rapidly."
Dr Gilpin says the high levels present mean wastewater testing can now be used to study particular variants of the virus.
ESR science leader Dr Brent Gilpin says wastewater testing will become even more important to detect different variants in the community