Septic trucks usually stop at a few different houses before they’re full, so the waste from several families ends up all mixed together. You’d have to mandate the collection and analysis of a single home at a time for what you said to be true. It would totally change the logistics of the industry.

Most people only pump their tanks every few years, so you’d be looking at a much longer history rather than what’s happening right now like you would with sewer water analysis. I just don’t see how data that old would be relevant.

Interesting considering many rural / red areas of the country are also more likely to be on a septic system and therefore can’t have their sewage monitored.