In addition to the RO, most also have carbon filters, so the water is pretty tasteless. Minerals and chemicals are almost completely gone, so if you use this for all your drinking water needs, you should supplement minerals in your diet. My wife and I buy milk in gallon jugs, and wash them out, and use them for water. It's the passage of water thru limestone that dissolves this over time into the water. Acid rain helps water dissolve this limestone even more.
Limestone is composed of calcium carbonate and magnesium carbonate.
Dolomite is crushed limestone that is made into pills for mineral supplements. However, These minerals cause problems with washing dishes, clothes, and bodies. It takes a lot more soap to get things clean. So, hard water is bad according to Madison Avenue. Removing calcium and magnesium from the water makes it soft, which uses less soap, and feels better on hair and skin.