I know better than to do this because you are always right, but I'll do it anyways...
If I give you a pressure washer under 5,000 psi and ask you to blast through 2 miles of rock, how long do you figure that will take you? FOREVER! And we only do that for 30 days, then get a good bit of the water back which is probably disposed of or reused. Huck is right when he says the majority of issues are caused by poor operating procedures on the surface, not from the actual fracking. The notion that water injected 2 miles below the surface, under layer upon layer of solid rock, will return to ruin your water well is pure nonsense IMO. If you beg to differ, I invite you to retest the 100+ water wells we have tested in Wetzel County, WV in the past two decades that surround the frack jobs we've done at much shallower depths than any Marcellus or Utica well. All those wells surround frack jobs that are 3K feet down and not once in the history of our drilling program have we ruined a water well from contaminants that can be linked to frack water seepage. All the instances of well water contamination were the direct result of improper operating procedures on the surface.
In regards to fracking fluids, we frack with 99.5% water and sand. We use a little bit of acid on the front end to "clean the pipes" so to speak. There is also some detergent and a clay stabilizer in there. So .5% of our solution is "chemical" in nature. Unless you consider the other 99.5% chemical sense water is a "chemical". But the notion that people are fracking entirely or mostly on caustic chemicals is a misnomer. It happens, but the vast majority of the industry is doing is the proper way and those who are not, are not properly representing the industry.
I'm not saying it is impossible for fracking to impact the water tables via seepage from those depths, but it is highly unlikely and virtually defies physics. If and when it does return to surface via natural migration through the dozens of rock formations between here and there, or some other remote possibility like "kimberlite pipes" (which are very rare and only found in areas known for volcanic activity whether it be past or present) we will all be long, long gone.