Despite ACT deputy chief health officer Vanessa Johnston's plea to the community on Saturday, testing numbers dropped again in the 24 hours to Sunday morning.

There were 228 tests in the past 24 hours and 267 the day prior.

The virus fragments may not indicate an active case of coronavirus in Canberra. Dr Johnston said it could represent a person who had recovered from COVID-19, was no longer infectious but was continuing to shed the virus.

This shedding can happen for several weeks after the person is no longer infectious. Dr Johnston said the sewage traces could be linked to someone who had returned from interstate after completing hotel quarantine.

"It is incredibly important to get tested for COVID-19 if you are experiencing even the mildest of symptoms, even just a scratchy throat or runny nose, and to self-isolate until you receive a negative result," Dr Johnston said.

"We want to make sure that if there is an undetected active case in the ACT that we can detect it quickly in order to keep our community safe.

"If you do not have any symptoms, there is no need to get tested."

Common symptoms of COVID-19 include fever, sore throat, cough, shortness of breath, and loss of smell or taste, while less commons symptoms include runny or blocked nose, muscle pain, joint pain, diarrhea, nausea, vomiting and loss of appetite.

Canberra's sewage is tested weekly for the virus. The positive detection occurred on January 27 only in the Belconnen testing location.

This testing site covers wastewater from Aranda, Belconnen, Bruce, Charnwood, Cook, Dunlop, Evatt, Florey, Flynn, Fraser, Giralang, Hall, Hawker, Higgins, Holt, Kaleen, Latham, Lawson, Macgregor, Macquarie, McKellar, Melba, Page, Scullin, Spence, Strathnairn and Weetangera.

All other locations in the ACT had negative sample results on 27 January.

ACT Health renewed calls for anyone with the mildest symptoms to get a COVID-19 test last week, since numbers dropped to between 200 and 300 per day.

Chief health officer Kerryn Coleman has previously said around 700 tests should be conducted daily to get a clear picture of whether the virus is within the community.

ACT Health is continuing to investigate and further wastewater testing will be conducted next week as part of the ongoing wastewater surveillance program in the ACT.

The ACT once again reported no new cases of coronavirus. There have been 118 cases in Canberra throughout the pandemic.