I'd be very careful of believing every claim that something has been 'proven'. What we are doing here hasn't been proven by medical standards and much of what our bodies actually do has been 'proven' to be impossible too.
The evidence that the minerals in water can't be absorbed is compelling. However I've also seen evidence to the contrary and as I've said earlier the evidence of billions of years of animals living on mineral water AND rainwater both really speaks for itself. So long as I can keep the chlorine and fluoride and any other civilised pollutants you can think of I'll be happy. Just like our food it's what we do to it or add to it that's the problem- the food AND the water as it comes from the ground is how we should be consuming it.