Advertisement COVID-19 has been detected in Victorian wastewater at least 13 times in the past month despite there not having been a single case of coronavirus in the community for 63 days â but experts say the testing program is working well. Wastewater testing is used all over the world to check for the presence of coronavirus and other diseases. Credit:AP Wastewater testing is a powerful but inexact early warning system, potentially signalling the start of a new infectious cluster before people even know they are unwell and is sensitive enough to pick up one sick person in a catchment of 100,000 people.