In addition, water is water, dissolved oxygen in no way changes water’s molecular structure. Dissolved oxygen is usually introduced into water through motion, i.e. precipitation, stream/river dynamics/agitation, poring water from one container to another. Water at higher elevations, may or may not (please site your source of this information) contain lower dissolved oxygen concentrations. However, since water absorption in the intestine, is by osmosis of the water molecule, what might be dissolved in the water is not necessarily transported across the intestinal mucosa, as each of these molecules would be absorbed/transported or not based upon their individual concentration in relationship to intercellular, interstitial and intervascular concentrations. The intestine is primary anaerobic (without oxygen), therefore I suspect oxygen concentrations in the area of the intestine where water is absorbed to be minimal at best. I think (do not know this for sure, but it is consistent with what chemistry and physiology I know) that any dissolved oxygen in consumed water would likely dissipate in the presence of stomach acids.

Pete