This is a surface water treatment plant and it gets the water from the Monongahela river. Treating surface water, particularly from a river, is complicated and energy intensive. If they were actually getting it from a well, or a spring, they could just pump it out, add some chlorine to it, and send it on its way. That’s why you can get water from a well and not treat it.

In that area I would be suspicious of ground water sources just because contamination by the fossil fuel industry seems to be so common. But that does not appear to be an issue with this water company