There were six cases of COVID-19 in the Hawkesbury on Monday morning, as greater Sydney entered its sixth week of lockdown.
At this stage, the lockdown is due to be lifted at 12:01am on Saturday, August 28.
However, NSW Premier Gladys Berejiklian said on Monday that vaccination rates would factor into the NSW decision on whether its lockdown will extend beyond August.
Testing hit a record 117,000 on Sunday, and Ms Berejiklian said it showed people were staying vigilant.
There were two COVID-19 fragment detections in South Windsor sewage last week, on Friday and Saturday, where there were no known cases.
"South Windsor sewage treatment plant serves about 19,000 people in Windsor Downs, Bligh Park, Clarendon and South Windsor," NSW Health stated.
"Everyone in these suburbs is asked to be particularly vigilant for the onset of symptoms that could signal COVID-19, and if they appear, to immediately be tested and isolate until a negative result is received."
The six cases of COVID-19 recorded in the Hawkesbury are from known sources of transmission. This figure has remained stable for the past week.
Cases numbers in the Penrith local government area (LGA) have been rising, with 29 cases in that area on Monday morning.
There were three cases in the Blue Mountains LGA, and 21 in The Hills Shire.
In the Blacktown LGA - which is currently under tighter restrictions than Hawkesbury - there were 206 cases with 69 of these from an unknown source of transmission.
There have been 15 COVID-19 related deaths during the current outbreak of Delta, which began in the eastern suburbs and has been moving south-west and west. On Monday, there were 232 COVID-19 cases admitted to hospital in NSW.
Last Wednesday (July 28), Puma Energy Marsden Park was listed as a COVID-19 "casual contact" venue for anyone who attended on Monday, July 19, from 11am to 11:05am.