Firstly, the most important thing to do is follow your state health department’s advice.
Fragments of the virus that causes COVID-19 were found in the Allambie Heights sewage network in Sydney, via samples taken on April 22 and April 26. Fragments were also detected in the Marrickville sewage network (via a sample taken May 3).
According to NSW Health, people in those areas should monitor for symptoms and “if you have even the mildest of symptoms (even if it appears to be a cold), get tested and self-isolate immediately.”
Viral fragments were also recently detected in Melbourne sewage.
But when it comes to wastewater monitoring for COVID-19, there’s a lot of probability involved. It doesn’t necessarily mean someone in your suburb definitely has COVID.