My hometown is one of 100 communities that is taking part in an experiment of estimating the local Covid-19 situation by measuring the level of the virus in the local sewer system. Seems like it might have promise. The article is behind a paywall, but you get 5 free clicks a month and if you click on an article you can keep returning to it.
The same is happening in Australia, where they are using the system set up for estimating illegal drug use by sewer monitoring.
(But in Australia, it’s already too late, because it’s all over.)
Or so they think. In communities where there are no confirmed cases they’re still finding it in the sewage.