Quote from @Hanish Sampath kumar:
I am currently under contract on a 1-bedroom septic, 3 full bath, (has 3 full bedrooms with loft space) cabin near Gatlinburg. Priced at 740 K. plus needs 30-40 K to set it up and running as a STR. Talking to some local contractors they told me there were 700 plus cabins in that area last year ran out of water and had to spend extra on water to refill their wells. Also cautions me on renting this cabin as a 3-bedroom 3 bath as I may not have the water capacity and may overload the septic leaching field. I have asked my home inspector to check the water flow speed in the well and he has not noticed any septic defects (this has been only used second home not on a rental so don't know the true capacity for both systems). I calculated the ROI based on 3 bedrooms in that area if I cannot rent it as a 3 bedroom this deal will not make sense for me. Anyone in the area who have experienced similar problems please shed some insights on this specific situation.
So based on your post, it sounds like there's no red flags with this particular well, just somebody saying that other wells have had problems in the area. Is that correct?
As Luke said, wells come with their own set of risks, nobody's going to tell you a particular well will never have a problem. That said, the overwhelming majority of properties in the Smokies are on private wells, and a vast majority of those are not having water production issues. If you are concerned, have a well professional come test the production level of that well.
Even if you do have to have water delivered, it's stressful but hardly the end of the world... there's services locally that will do a same-day water delivery, it costs a few hundred bucks. I've done it twice, over 5 years with 7 cabins on wells. Just the cost of doing business.
Re: septic, there are lots of properties in the Smokies that have more functional bedrooms than the septic capacity says. I own two and I've never thought twice about it. You probably don't want 20 people using that septic system every night, but you probably don't want that many people anyway for plenty of other reasons. If you're concerned about it, I'd recommend calling a septic company or three and asking them if they see very many issues with this sort of thing.