Watch....I, too, am in favor of using the Sauna during a Water Fast. Have you noticed how your Body tends to perspire naturally when overloaded with Toxins? Coffee does it for me every time.
I've used a public steam Sauna during the first days of a WF with good results. However, I would think the longer you go on water, the less you should go to the Sauna. But I haven't gotten there yet.
Work in progress.....WY