In our area, southern colorado, the worst seems to be a fine, with the possibility that they could "shut you down" in some form or fashion ... my guess is a "cease and desist" from the city/county/health authority's lawyer.
We planned for this by putting in a septic system in a DIY install ... permitted, inspected, and then never really used for poo/greywater. Those head off to separate
humanure and greywater systems. But, the septic system is there, both in case someone complains and in case we have to fall back to it one day. We saved about half of the cost, as we did the labor ourselves ... only had to buy parts/materials, and pay someone to mini-excavate. We also will save on future pumping costs, as there shouldn't ever be anything to pump.
We have 40 acres around us, but I'll bet there are ways to do humanure/greywater in stealth mode, and accomplish the same thing in a more "nosy neighbor" environment.
Of
course, if we ever get such a "no poo" order from the authorities, selling it on ebay might cover the fine ...