Obviously, the temperature of water does not affect its chemical composition. At least not in the ranges we are likely to drink it in. Yet it is clearly far more pleasant and refreshing to drink cool water than it is to drink tepid or warm water.
Is there actually any difference to the organism or is this just a matter of perception? Is cool water somehow more efficient at rehydrating a cell? In any case, surely by the time water reaches individual cells it will have warmed up to body temperature.
So, what, if any, is the difference between drinking cool and warm water in terms of its effect on the human (or other animal) body?
Extra bonus for explaining why the taste of water changes when it is cold.