Acting Chief Minister Nicole Manison told media on Monday that although the number was high, it was not surprising.

"Fourteen of these cases are from households in the four streets in Katherine East zone where we have been out there doing testing," she said.

"The blitz is working. We are finding the cases that we thought were there, and we can expect more cases."

Of the 14 cases, eight are under 12, five are in their 20s, 30s and 40s and one woman is in her 70s.

They will all be transported to Howard Springs today.

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Two other people have tested positive from the cluster while in Howard Springs - a male teenager and a man in his 70s.

The NT cluster is now at 87 cases.

The other new case was someone who arrived in Darwin on a repatriation flight from Singapore.

Ms Manison said a Binjari resident who visited Timber Creek had also returned a "provisional positive" result to a COVID test.

"That still needs to be confirmed. He is now in isolation while we look at that test again," she said.

"So there is no direction for Timber Creek right now. But this may change."

Wastewater results from across Katherine have now come back positive, with Ms Manison saying this meant COVID has spread across the area.

"We are now seeing positive wastewater results across the Katherine Township, not just in Katherine East," she said.

"This indicates that there has been further spread over the last few days, which is why it is so important that Katherine residents go and get tested if they have symptoms.

"Even if they have had a negative test before, given that we know COVID Is in the community, you can still catch it."

She said there was also a chance that COVID had also made it into surrounding communities.

"And I do want to flag that there is a very strong chance that there will be communities that have active cases. So it is likely that we are going to have to escalate our responses to some of these communities to a lockout in the next day or two," Ms Manison said.

Chief Health Officer Hugh Heggie has implemented a new direction which means anyone who has been in Katherine, Binjari or Rockhole since November 29 has to get tested for COVID-19.

"This effectively means all of Katherine is now an exposure site [as is] Binjari and Rockhole. So if you have you ever been in Katherine any point in the past two weeks in those areas, and you are now outside of Katherine, please go get a test in the next three days," Ms Manison said.

"This is going to be the best way that we can get a full picture on exactly where the spread is so that we can slow down our wider spread."

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