Recently, more than 40,000 people living in around a dozen suburbs in Sydney were asked to get tested for Covid-19 after traces of the novel coronavirus were found in sewage water in the areas despite no new local cases.
How sewage water can alert authorities on Covid-19 hotspots, virus strains
![How sewage water can alert authorities on Covid-19 hotspots, virus strains](https://www.precisionhealth.in/wp-content/uploads/2022/09/news9.jpg)