I replied to John near the top of the thread but wanted to post here too. My location is in the northeast U.S., a 15-minute drive from the nearest city (50k pop) which is a college town in a growing tourist destination, so not terribly remote. It's a guest suite in my home, with a well and septic in a rural agricultural setting. Fortunately, WiFi is reliable on most networks here and guests can easily navigate with Wayz, Google Maps, etc. I've been hosting here since 2012.
I alert guests to the well and septic 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. I also give driving times to the nearest gas station, grocery, etc.
This can be rather lengthy for them to read, but my aim is to manage expectations. 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. They also need to be cautioned about deer and other wildlife on the roads after dark. Most of my guests are enthusiastic and cooperative, and many agree with water conservation methods. I provide filtered water for guests in attractive bottles because the well water has a high iron content.
I just had my septic system replaced (it was very old). Sorry to be gross, but the contractor said there were condoms clogging the baffle — definitely from guests! So now my bathroom sign lists condoms at the top of a list of the things that should never be flushed, like tampons, cotton swabs, cleansing cloths, coffee ground, etc. I think you have to spell it out. The sign is on the wall as you face the toilet, so the men will see it!
I also have a Guest Guide in a notebook which I leave open on the table before they arrive. The first page describes all of this plus wildlife and keeping cool without AC. Whether they read it is something I can't police but I am on-site so I greet most guests, call it to their attention, and check in with them daily. They do not have a kitchen sink so I wash their dishes. I collect the dishes when they are out, which they know is going to happen during their stay, giving me an opportunity to make sure nothing is damaged and the door is locked.
Hope this is useful. Best,
Patti