[matthewbauer]

Why is the mineral issue bunk?

According to this WHO report[1], it seems like a real concern:

"Low-mineral water markedly: 1.) increased diuresis (almost by 20%, on average), body water volume, and serum sodium concentrations, 2.) decreased serum potassium concentration, and 3.) increased the elimination of sodium, potassium, chloride, calcium and magnesium ions from the body. It was thought that low-mineral water acts on osmoreceptors of the gastrointestinal tract, causing an increased flow of sodium ions into the intestinal lumen and slight reduction in osmotic pressure in the portal venous system with subsequent enhanced release of sodium into the blood as an adaptation response. This osmotic change in the blood plasma results in the redistribution of body water; that is, there is an increase in the total extracellular fluid volume and the transfer of water from erythrocytes and interstitial fluid into the plasma and between intracellular and interstitial fluids."

It might not be enough to outweigh the benefits of highly filtered water, but just because you have enough minerals from food doesn't mean that minerals in water aren't having an effect.

[1]: http://www.who.int/water_sanitation_health/dwq/nutrientschap...

[Laforet]

This particular report cites a number of rather fringe sources as well as many non-English journal artiles that cannot be easily verified. Overall I find the author's conclusions hard to believe.

>It was thought that low-mineral water acts on osmoreceptors of the gastrointestinal tract

This is not how osmolarity sensing works.