RO water is stripped of it minerals. Water in general is a strong solvent. [FONT=Verdana, Arial, Helvetica, sans-serif]RO water without any substance is as unnatural as a pocket of vacuum within a normal atmosphere. A pocket of vacuum will suck any and everything around it until the pressure becomes equal to the surrounding.
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Likewise, RO water will leach out any and every substance that it can dissolve from the substances that it comes into contact with, until it's content reaches equilibrium with it's surrounding or the water is saturated with the substances so that it can no longer dissolve any more substances.
Knowing this, where do you think the RO water gets the minerals from to reach equilibrium once you ingest it? All of my customers that have RO systems due to their poor water quality all use ionizers to add back the essential minerals to their water before ingesting or using it for watering their plants. RO water will also become acidic over time as it's exposed to the air it will absorb CO2.
Feel free to argue with this if you want, but you can't deny the chemistry.