> What the hell happened in the last 20 years?

This is a well known target for data collection, going back well beyond 20 years. It has been proposed before that municipal sewage systems be monitored for byproducts of explosive and chemical weapons manufacturing, as well as surveying illicit substance use. Ambassadors have long been careful about where they take their dumps, and porta-shitters occasionally pop up on embassy grounds during periods of high tension - despite having a functional sewage line.