>>48287476it's because of the accessibility of the oxygen. oxygen in water is bonded to the hydrogen and if you 'breathed in' water, there's only two things that'd be permeating into your blood; water, and the free-floating oxygen dissolved in it. the latter is what fish live off of, but it's not nearly enough for air-breathing creatures to, and you'd otherwise just be getting more water into your blood - your body can't 'extract' or strip the oxygen from the hydrogen.
