I wonder itf it is the temperature reduction that you are getting, not the water per se, that is helping. There's been a lot of documentation that lowering one's temperature helps with symptoms. That's why there are those neck ice packs. And there was a really promising device, where you grip your hand on it for awhile and your temperature is reduced, that was potentially being marketed to people with MS. If I remember correctly, it was a Stanford professor whose wife had MS who developed it. A lot of athletes use it because it enhances their performance too (and it is not a banned substance. yet.).