AQUASALT is 100% produced using the Evaporated Food Grade Salt Process in the two newest and most technologically advanced salt plants in the U.S.A. This process produces the highest purity salt possible. Our salt is so pure it is used in the pharmaceutical industry and is certified as USP Grade. AQUASALT is the purest salt available for swimming pool and spa chlorine generators. The evaporated process is familiar to most people as table salt or food grade salt.