Well and septic, rural agricultural — I can relate! John, I also notify them in a pre-approval message, pre-arrival message, printed house manual, and a sign in the bathroom. I have custom saved messages for Newbies vs Experienced guests to emphasize certain points.
My listing description has this info as well as House Rules. This can be rather lengthy to read, but my aim is to manage expectations. My location is a 15-minute drive from the nearest city (50k pop) which is a college town, so not very remote.
I just had my septic system replaced (it was very old) and the contractor said there were a lot of condoms, definitely from guests! Sorry to be gross, but urban and suburban guests need to be explicitly cautioned at every opportunity how to treat waste and water in areas where basic municipal services do not exist. I have a Guest Guide in a notebook on the table when they arrive, describing everything thing from wildlife to water conservation. Whether they read it is not something I can not police. But I am on-site so I check in with them daily and inspect while they are out, which I tell them will happen.
I also give distances to the nearest gas station, grocery, etc. Fortunately, WiFi is reliable on most networks here and guests can easily navigate with Wayz, Maps, etc.
Best,
Patti