The science is in. Minerals in water play a large role in health and a lack of minerals in water cannot be compensated for by diet.
Water for drinking should always contain some alkaline minerals. At least 50 mg/L but ideally 150 mg/L or higher. You may have heard that minerals in water aren’t nutritionally available and thus cannot contribute toward health. That theory has been disproven. In fact, the World Health Organization has even issued a warning against drinking demineralized water.
After analyzing hundreds of scientific studies concerning demineralized water, the World Health Organization released a report stating that such water "has a definite adverse influence on the animal and human organism."
What is alarming is that consuming demineralized water for even just a few months can create serious side effects. "The effects of most chemicals commonly found in drinking water manifest themselves after long exposure." However, "only a few months of exposure may be sufficient 'consumption time effects' from water that is low in magnesium and/or calcium."
Illustrative of such short-term exposures are cases in the Czech and Slovak populations who began using reverse osmosis-based systems for final treatment of drinking water at their home taps in 2000-2002. Within several weeks or months various health complaints suggestive of acute magnesium (and possibly calcium) deficiency were reported. Among these complaints were cardiovascular disorders, tiredness, weakness or muscular cramps." Again, serious side effects within just several weeks or months.
It gets worse. When demineralized water is consumed, it also leaches minerals from the body. This means that the minerals being consumed in food, vitamins, and supplements are being urinated away. Fewer minerals consumed plus more minerals being excreted equals serious side effects and big health problems. In a scientific study performed to see if minerals consumed in food can make up for the lack of minerals in water, scientists concluded that "reduced mineral intake from water was not compensated by their diets...low-mineral water was responsible for an increased elimination of minerals from the body."
"It has been adequately demonstrated that consuming water of low mineral content has a negative effect on homeostasis mechanisms, compromising the mineral and water metabolism in the body." Consumption of reverse osmosis water "leads to the dilution of the electrolytes dissolved in the body water. Inadequate body water redistribution between compartments may compromise the function of vital organs. Side effects at the very beginning of this condition include tiredness, weakness and headache; more severe symptoms are muscular cramps and impaired heart rate."
Beware of water filters that remove all the minerals and add minerals back in. On this trend, the World Health Organization states that "possibly none of the commonly used ways of re-mineralization could be considered optimum, since the water does not contain all of its beneficial components. In the case of borderline deficiency of a given element, even the relatively low intake of the element with drinking water may play a relevant protective role."
It's practically impossible to recreate natural water with all of its minerals and trace elements after it has been demineralized. Why drink this type of water at all when healthful alternatives are available?