Anybody who also uses a water softener would have had at least rudimentary tests performed on their water to determine what the softener has to deal with, and county code doubtless requires health testing when a well is dug unless, maybe, it’s a very old one grandfathered in.
Anyhow, it’s theoretically possible the company f-ed up the aquifers and then went dancing la la la, but that sounds like an extremely foolish move on their part with Uncle Sam breathing down their necks all the time right or wrong.
"Theoretically", yes.
But, almost certainly, NO!
First, we're talking Pennsylvania -- almost the entire stte is underlaid by coalbeds of one depth or another. Which means that most wells are naturally subject to intrusion by coalbed methane and need to be vented.
Second, the Marcellus Shale strata being fracked is a mile-and-a-half (or more) beneath the aquifers tapped for well water and any coalbeds -- and separated from them by several other impermeable strata.
Speaking from the middle of the Barnett Shale, where horizontal drilling and fracking was first employed in the early nineties, the Dimock complainers (and the EPA) are full of it.
Let's start with any well water tests made before the drilling began. I'd wager there was evidence of methane.