The catchment, which includes Shepparton, Shepparton North and parts of Orrvale and Kialla, first tested positive for traces of COVID-19 on August 10 and 11.
Repeat detections of wastewater samples have since been discovered on August 13 and 16.
GV Health chief executive Matt Sharp urged the community to remain alert to COVID-19 symptoms.
"Anyone from the Greater Shepparton area who is unwell with any symptoms of COVID-19, no matter how mild such as fever, chills, cough, sore throat, runny nose, loss of sense of smell should get tested immediately any stay at home," he said.
"Do not go about your normal day to day activities such as work or going out in the community. Please do the right thing and do not place your family members, friends, colleagues and the broader community at risk."
GV Health COVID-19 vaccine program executive lead Alicia Cunningham said COVID-19 tests across GV Health's hubs had doubled since the news first broke of the potential threat of COVID-19 in the community.
"Prior to the wastewater detection, GV Health was conducting approximately 100 COVID-19 tests per day," she said.
"Since then, we've been testing around 200 people per day. This is very encouraging as it shows that our community is doing the right thing to get tested if they have COVID-19 symptoms, no matter how mild."
In the past month in regional Victoria, positive readings for COVID-19 wastewater fragments have been detected in Bacchus Marsh, Benalla, Bendigo, Black Rock, Healesville, Koorlong, Lakes Entrance, Somers and Wangaratta.
No known cases in Benalla, Healesville, Lakes Entrance or Wangaratta have been found.
On Tuesday, Chief Health Officer Brett Sutton said positive wastewater wasn't "definitive of being a case there," but urged anyone symptomatic in areas where samples had been detected to come forward for testing.
"If you live or work in these areas, you don't have to reside there, if you are moving into those areas, especially as an essential worker, please get tested," he said.
Victoria recorded 24 new locally acquired cases of COVID-19 yesterday, with all but six cases in isolation throughout their entire infectious period.
Three cases remained under investigation by health authorities with continued concern over a string of mystery cases in the St Kilda area.
More to come.
