According to Dr. John Sorenson, a leading authority on mineral metabolism.
Research on heart disease and cancer shows a healthy water is hard and moderately high in TDS (total dissolved solids). Why do people purchase these de-mineralized or water softening systems? Usually their thinking goes something like this. "I know I should drink water, but it's so polluted with chlorine, chemicals and toxic metals, that it's not safe. So I'll get rid of these harmful things and all will be OK."
Not really. Creating a "healthy water" means removing the harmful agents but keeping the beneficial minerals. "Minerals in drinking water are more easily and better absorbed than minerals from food," according to Dr. John Sorenson, a leading authority on mineral metabolism.
Purifiying devices remove everything from the water, harmful bacteria and beneficial minerals. This stripped water cannot sustain life even in a fish bowl. All fish require minerals to prosper, and if allowed to live in these types of water will perish. If this type of water is ingested for long periods of time, it can leach out valuable body minerals such as potassium, magnesium, sodium and calcium. Mineralized water is needed for all cellular functions and if there are no minerals in your drinking water your body will rob the minerals from somewhere in your body to satisfy its needs. One can take mineral supplements to replace them however, it is not easy to replace the minerals in our bodies in the same form that we lost them. References: (5) , (7) , (22) , (44) , (46) , (50)