I always buy distilled, because the water has been boiled. The water
usually has an expiration date.
Don’t buy a regular bottle of regular drinking water
or spring water. This water contains more contaminants than you think—not enough to make you sick if you drink it, but you don’t want to add them to the other germs you are working to get out of your sinuses.
Buy some table salt without iodine. Iodine is an irritant to some people.