A Hunter man in his 60s and another in his 40s are the latest Hunter residents to be diagnosed with COVID-19.
The man in his 60s is part of the known family cluster in Port Stephens, and he remains in isolation.
"We are currently working to identify all close contacts of this case, who are being placed in isolation," a Hunter New England Health spokesperson said.
The Port Stephens family cluster, which now includes seven cases, is linked to the Thai Rock Wetherill Park cluster.
The second confirmed case is a man in his 40s who is a returned overseas traveller.
The man is a resident of the Hunter New England region, however, has remained in hotel quarantine in Sydney since his return.
It comes as NSW Health confirmed there had been 18 new cases diagnosed in the state between 8pm on July 28 and 8pm on July 29.
NSW Health has recently begun to test sewage for traces of COVID-19 across the state, and sampling has begun at a number of metropolitan and regional locations across NSW.
Initial samples collected at the Perisher sewage treatment plant on Wednesday, July 22, returned a positive result for the presence of COVID-19.
Further sampling and analysis is required to assess the significance of this initial positive result.
NSW Health said the positive sewage result can be due to "shedding" of the virus by someone who may have previously had the illness. The virus can shed through their system for up to four weeks later.
While no cases of COVID-19 have been identified in Perisher or Thredbo to date, NSW Health said it was important that anyone who was in the area get tested if they have even the mildest of symptoms.