A 70-year-old man who travelled from Indonesia to Darwin on his own yacht has tested positive for COVID-19.

Authorities say the man is the only new case of the virus reported in the Northern Territory in the past 24 hours.

He arrived in the Territory on July 13 and is in quarantine under the care of the NT Centre for National Resilience with mild symptoms.

The case came as coronavirus fragments were also detected in wastewater samples in Darwin although authorities say there’s no risk to the wider community.

A continued surveillance program detected the fragments at the Ludmilla Treatment Plant which is the catchment for wastewater from more than 10 Darwin suburbs.

The Centre for Disease Control has confirmed there are people who have recently been at the Howard Springs quarantine facility who live in this area and are likely shedding the virus fragments following their recovery.

“These people are not infectious and there is no risk to the community,” NT Health said.

Further testing of wastewater across Darwin and in the Ludmilla catchment will be conducted to monitor the situation.

The Northern Territory is currently dealing with four other active local COVID-19 infections and another four cases in returned travellers.

It has border restrictions and quarantine requirements in place for NSW, Victoria, Queensland and South Australia.

-AAP