There are three new cases of Covid-19 in managed isolation and none in the community, the Health Ministry says.
Two travellers arrived this week from the UK and India and were detected during their first test. A third person contracted Covid in isolation was a contact of an earlier case who had arrived from India.
There are now 23 active Covid cases in New Zealand.
Meanwhile, wastewater testing in Rotorua returned a negative result. The testing was ordered after it yesterday emerged weak positive results had been detected in wastewater in Wellington, Christchurch, Rotorua and Queenstown.
Queenstown and Wellington have now also returned negative results, while results from Christchurch are pending.
The ministry said there was no risk from the wastwater.
"The Ministry's current assessment remains that the weak positive results are likely from recent positive cases in managed isolation or due to recently recovered cases who are not infectious but continue to shed the virus after returning home or while travelling."
The ministry said it remained really important to New Zealand's response that anyone displaying symptoms consistent with Covid-19 to stay at home and promptly call Healthline about getting a test.
Any cases of Covid-19 need to be detected quickly in order to stop the virus spreading in our communities, said the ministry.
As well as using the Covid tracer app, people were asked to maintain hygiene measures including wearing a face covering on public transport, washing hands and coughing and sneezing into your elbow.