The Options are:
1. Make sure that you require that the well be tested. This testing should include a water quality sample and also a short pumping test on the well. In addition, the homeowner should provide you with a detail of the well log. This log should have been prepared by the driller with the well was put in.
2. Also document the static water level and dynamic water level in the well.
3. On the septic issue, get the system inspected and if possibly conduct a hydraulic load analysis.

There is no way of "ensuring" that the well will not dry out. Also the septic system, I believe, is supposed to be a certain distance away from the well to prevent cross contamination in the event that the septic system goes bad or overflows due to the owner not having it serviced in a timely fashion. I am not sure what the requirements are, but your inspector will know.

Terrence Charest, e-Pro