https://wastewater-observatory.jrc.ec.europa.eu/#/content/th...
Also, Wastewater analysis and drugs — a European multi-city study:
https://www.euda.europa.eu/publications/pods/waste-water-ana...
Yep. Not just drugs are monitored this way, but also the spread of infectious diseases. That can lead to sometimes pretty weird findings - for example, polio virus is supposed to be extinct, but every so often it shows up in sewage monitoring of major German cities [1]. The cause most likely are people (tourists and immigrants) from Africa and Asia that got an attenuated virus-based vaccination in their home country shortly before they came here.
Covid is, at least in Bavaria, also part of the regular monitoring schedule [2], Austria monitors for Covid, RSV and influenza [3].
[1] https://www.aerzteblatt.de/news/erreger-der-kinderlaehmung-i...