Anyone who was at the clinic between October 3 and October 10 should get tested,isolate for 14 days from the date they attended the clinic,continue monitoring for symptoms and,if any symptoms develop,get re-tested,Dr Chant said.

Sewage testing has detected traces of the SARS-CoV-2 virus at the water treatment plant in Quakers Hill on October 13.

"The plant serves Sydney’s west and north-west where there have been recent cases,so that may be the explanation,but for the utmost caution we are asking people in that area to come forward and get tested if they have any symptoms,"Dr Chant said.

From Friday,outdoor venues would be allowed to seat patrons 2-square metres apart if they have a QR code. Also,the number of people permitted to attend outdoor concerts has risen from 20 to 500.

Ms Berejiklian foreshadowed further easing of restrictions next week if Dr Chant was happy with the number of cases recorded over the weekend.

Dr Chant also gave updated advice on venues where patrons and staff are believed to have been close or casual contacts of cases.

• Bargo Hotel,Great Southern Road,Bargo,on September 26 between 7pm and 9pm. Patrons or staff who were there for an hour or more during this time are considered close contacts and must get tested,regardless of symptoms. Patrons or staff who were there for less than one hour during this time are considered casual contacts and must be tested should they have any symptoms;

• Spotlight Plaza,147 Queens Street,Campbelltown,including the Spotlight store and Gloria Jean’s on September 26 between 11am and 1pm. Patrons or staff who were there for less than one hour during this time are considered casual contacts and must be tested should they have any symptoms;

• Narellan Town Centre, September 26 between 3pm and 5pm. Patrons or staff who were there for less than one hour during this time are considered casual contacts and must be tested should they have any symptoms.