Originally Posted by
Bluebulldog
Odd scenario.
Typically a septic can't be installed without a qualifying building, as you need to show occupancy, and calculations for waste water, set backs etc.
A well usually won't be drilled unless there is a record of same, as there are specific requirements under the Source Water Protection Act.
OP, if it's a decent deal, I'd go for it. The age of the building, and the subsequent work, would indicate that even if the structure was done without permit, it likely is grandfathered, as evidenced by the septic, and most recently the well.
Does the township have an interactive mapping site that shows the structure? If so, that's a very good indication that it is.