I use the hot water from my shower, and that comes from a well 250 feet underground. It just seemed too much of a hassle to use distilled water and heat it to a comfortable temperature and all. I've sometimes wondered if that was dangerous, but I just don't want the hassle. I've been using a neti pot and saline water from a squeeze bottle a couple times a day to help with a sinus infection, and it seems to be working nicely. I had been using it only a couple times a week.