The bath water is natural artesian water, that comes from the Great Artesian Basin. The mud we pour into the baths is more of a milky clay, and the minerals it contains are thousands of years old.
You soak in the bath for 30mins, and then hop out to pat the mud pack on your body, which takes 5-7mins to settle or dry.
Then you get back in the bath, and soak off the mud pack for another 15mins.