Health authorities have encouraged anyone with coronavirus symptoms to get tested promptly after a Wellington wastewater sample tested weak positive for the virus.
This also applied to people who had recently visited Wellington.
Late on Friday, ESR reported a weak positive result from a Wellington wastewater sample. "A follow-up sample yesterday returned a second weak positive result," the Ministry of Health said at today's Covid update.
"Based on our experience, it is most likely that the two weak positive results are due to recently recovered cases continuing to shed the virus."
In recent weeks, three recovered cases who live in the Wellington region have left the Auckland quarantine facility at the Jet Park hotel.
A further historical case left a Wellington managed isolation facility the same day the second wastewater sample was taken.
"Additionally, it is possible that one or more recently recovered cases from elsewhere could have flown into Wellington," the ministry added in a media release.
ESR said if just one recovered person was shedding the virus, it could be detected in wastewater.
There was one new case of Covid in managed isolation to report today and no new cases in the community.
The seven-day rolling average of new cases detected at the border is none.
New Zealand's total number of confirmed cases since the pandemic began is 2290.
Quarantine-free travel between New Zealand and the Australian state of Victoria remains open following news of a community case announced in Melbourne last Tuesday, May 11.
People who'd been to any locations of interest in Melbourne recently should not travel to New Zealand for 14 days after being at the location of interest.
A dozen locations were outlined on a state government website. Those locations included some train stations and supermarkets.
The Ministry of Health said the public health risk to New Zealand from the community case in Melbourne announced on Tuesday was low.
Anyone already in New Zealand who had been at a location of interest in Melbourne during the time specified has been urged to call Healthline for advice on isolating and testing.
The ministry's contact tracing team has been contacting by email about 4500 passengers who recently travelled from Victoria to New Zealand to remind them of the above measures.
Two people in New Zealand earlier contacted Healthline and identified themselves as casual contacts. One returned a negative test and public health staff deemed the other person didn't need to be tested.
PM shuts down 'level 2.5' speculation
Prime Minister Jacinda Ardern on Friday shut down the idea that New Zealand will return to life under Covid-19 alert level 2.5 when borders open.
That came after director-general of health Dr Ashley Bloomfield floated a future vision that opening up the country's borders to vaccinated tourists could require Kiwis to return to alert level 2.5.
Speaking on Newstalk ZB show Mornings with Kerre McIvor on Friday, Ardern said it would more likely be a "1.5 environment".
"I spoke to [Bloomfield] and he said he was referencing more a 1.5 environment, with things like QR code scanning, those kind of things we need to be aware of on a day-to-day in that transition period," Ardern said.
Ardern's comments came in response to a caller who was worried the country was now being restricted to gatherings of 10 again.
Ardern was quick to say that was not the case, saying it was a discussion about creating extra "buffers" when we do open the borders, which could be at the end of this year depending on vaccination rates.
She said there was no suggestion that for three to five years New Zealand would be in a constant level of a 2.5 environment.
"A lot of it is going to come down to how many people we have vaccinated. The more people we have vaccinated, the more freedom we can have."
She said in the same way the country had immunisations for measles, there were still outbreaks from time to time and it was necessary to contain those.
Ardern also said she would be getting her first Covid-19 vaccination "soon" before she heads to Australia to lead a trade and promotional delegation.