Those who arrived since November 5 have been sent a message with NSW Health advice and are being called to be alerted to a number of venues of concern in Auckland.

NSW Health said in a statement that no passengers arriving in Sydney from New Zealand on Friday evening reported having attended the venues of concern and none had symptoms.

"Airlines will ascertain if passengers have attended these venues before they leave New Zealand and if they have, they will be not allowed to travel."

All arrivals from New Zealand will be asked to monitor for even the mildest of symptoms and get tested and isolate if they appear unwell, NSW Health said.

It said the risk posed by quarantine-free travel remained low.

NSW's sixth consecutive day without locally transmitted cases came as Victoria reached a fortnight without any.

One case - a returned traveller in hotel quarantine - was diagnosed from 18,941 tests reported to 8pm on Thursday.

NSW Health's Dr Jeremy McAnulty thanked the community for the increase in testing numbers, but urged people in the Rouse Hill, Bowral and Moss Vale areas to get tested after traces of the virus were found in sewage.

"Anyone in these areas is urged to get tested immediately if they have any symptoms at all that could signal COVID-19," he said on Friday.

While detection in sewage samples could reflect the presence of older cases in those areas, NSW Health fears there could be other active cases in the local community.

Australian Associated Press