There have been two positive detections of Covid-19 in wastewater in New Plymouth.
Ministry of Health says based on previous incidences, it is most likely the two positive wastewater results are due to recently recovered cases continuing to shed the virus.
A second positive result was returned this evening.
The ministry said it is investigating whether any recovered cases who live in the New Plymouth area have recently left a managed isolation facility.
"Additionally, it is also possible that other recently recovered cases from elsewhere in the country could have travelled to New Plymouth."
ESR consider a single recovered person shedding the virus may be detected in wastewater.
The ministry said while the mariners aboard the Playa Zahara and Viking Bay vessels recently docked at Port Taranaki in New Plymouth, they did not appear to be a factor in the wastewater detections.
"Additional testing is being carried out for a small number of port workers and nurses, who have been in possible contact with the mariners. The nurses have previously been tested for Covid-19 and returned negative test results."
The ministry is encouraging anyone with symptoms, especially if they are in the New Plymouth area, to get tested. Additional testing capacity is being set up in New Plymouth.
"We are closely monitoring this situation and additional public health advice will be provided if, and when, required."