I think it's really interesting that wastewater is a source of so much sheer information. I never knew before Covid that you could do public health surveillance against wastewater contents. I wonder how local you can make it — like does the data collection and analysis have to be "per city" or can it be "per neighborhood".
It's been used in Australia for decades, for public health monitoring (various pathogens) and estimating drug use etc.
It can be refined to "upstream of collection point" - what that means depends upon the wastewater sewerage map of the region in question, often estate developments will all pipe to a common outflow from that estate that then joins a larger wastepipe.
How that plays out in any specific city will depend on the utility map.
There's an urban legend that if POTUS is travelling overseas, he craps in a portable toilet, so that enemy spies can't analyze his shit. But last time I looked there was only one website saying that this is the case.
Nowadays I've read that Putin does this too, but I'm guessing that's an urban legend as well.
