Traces of Covid-19 have been found in Wellington's wastewater, the Ministry of Health said in a statement Sunday.
The first weak positive was detected in a sample taken in Wellington on Friday and a second time in a follow-up sample on Saturday.
The ministry said the results are likely attributable to recently recovered cases.
"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. A further historical case left a Wellington managed isolation facility the same day the second sample was taken.
"Additionally, it is possible that one or more recently recovered cases from elsewhere could have flown into Wellington."
Nevertheless, the ministry said anyone with symptoms, especially if they are in the Wellington region, should get tested promptly.
One new MIQ case
One new MIQ case of Covid-19 has been reported today by the ministry. It said there are no new community cases.
The case arrived on May 10 from the United States and is currently in a managed isolation facility in Auckland.
The total number of active cases in NZ is 19.