a bathtub whirlpool is perfectly fine. You put new fresh water in every time you use it. A hot tub is quesitonable. We have one in our yard, and haven't used it this year at all. If its your own and you keep good control of the chemicals, its not really a problem, but public hot tubs are a bad, bad idea -- for anyone. Google "hot tub lung" and you'll never go in one again.