Welcome from west Texas. The pillows work pretty well - where you are, those with some kind of plastic container like tupperware will probably get you by. Plastic ware because it seals so well. As here'sjohny indicated, one of the main things about using distilled water is to keep mineral build-up out of your hydrating system. Since you're not doing long term storage, and water pillows will eventually be thrown out, distilled water isn't really necessary. Use the cleanest water you can get and call it good. If you're feeling purist, distilling your own, like shelby said, would be pretty easy.