hmm good question, since we all do take herbs naturally as well.
My vote? I go with heated for this main reason, the ionised water 8)
oxygenated water is so beneficial, and warmer waters are better for your kidneys
and liver anyhow as well.
I never drink cold drinks, I drink room temperature water,
or heated /ionised water as for use in a tea.
Cold drinks are hard on kidneys and liver and stress them