I do know there is a water purification system in the house, so apparently water contamination to some degree was an issue with the former owners.
I would take the time to visit a few of the neighbors and see what kind of water problems exist in the neighborhood. Neighbors usually know about one another's water and septic problems. They will have known the prior Owners and this will give you a heads up regarding what remedial measures might be taken. And you'll be seen as taking more of an interest in the property than most average Agents.
You may have to trade some gossip to get what you want; but remember these people may be needing you at some point in the future and this can be a very nice way of introducing yourself . . . . it's the easiest prospecting you'll ever do. Under these circumstances, you're not a threat and your inquiry will be welcomed.
At this moment, you can be perceived as having control over who their future neighbors will be . . . . take advantage of it.
I think what you earlier said had been described as a
"Bored Well" is also known as a
"Driven Point" . . . . at least it is in this area, and hardware stores still sell the hardened points (with an attached porous body) that people actually drive into the ground until they strike a vein of water.
And I have NOT been able to find a way to sanitize a Driven Point with Chlorine Bleach.