showering on Yom Tov

Question

Are there any problems with showering on Yom Tov...with hot water... How about in a large hotel (or dorm) where the water tank and volume used is so large that it is almost inconceivable that your measly shower will cause anything to happen, or, even if it would, there would certainly be a non-jew simutaneously using the hot water....... Just curious (3 day yom tovs, while great for soul, are rough on the body)