Thank you! I did think that what I put in barn for personal use is not at all the same as when it is a venue. So many rules and regs to look into...! The mix of property use is going to tangle things.I know you mentioned the # of bathrooms vs septic system but I think what you are talking about would probably fall under commercial use which here in Washington has a whole different set of rules ( my desk is next to the wastewater engineers so I here alot of there conversations). Something your friend might want to explore
I was hoping I would also be allowed to use portable septic tanks for the smattering of potties I put around camp, go around with my little camp truck to collect those, dump into my own septic tank, clean, air out, put back into potty house. Not terribly concerned about sawdust going down, too. I would likely be on 3 year pump out schedule.
I might need larger tanks to start with, given my eventual plan. Adding on later would be a bit worse on settled land. I did that here, my septic supports 4 bedrooms but I have 2.
So far, she seems to be set on compost toilets only, does not want septic system (I think she doesn't want to maintain it, and, do everything as cheap as possible). I am more on the line of paying for modern conveniences. I just don't want to be digging a hole a couple times of week in a potty compost pile. I have better things to do with my time... She also found out that she underestimated the new potty pile she made, as she is there almost full time now, and that makes a difference as to .... volume.
I can't get excited about multiple poop hills, no matter how far from main camp or how hidden.