The problem with well water is all the pesticides that farmers use on their crops. In our area, cotton farmers also spray defoliants on their crops every year. Hundreds of tons of Roundup are sold to farmers every year. Mercury from rain water also seeps into ground water. You should see the horrible crud left in the bottom of our distiller. Yeech ! Distilled water at the store is sold in the same jugs used for milk.
We love our distilled water - we use it in our coffee, tea, and we refill bottled water bottles with it.