DEIONIZED DISTILLED WATER Deionized Distilled Water is produced by deionizing Distilled Water. This water is used as a reagent in a liquid chromatography test that requires a low ionic or organic impurity level. Because of the importance of this high purity, water that meets the requirements for Purified Water may not be acceptable. High-Purity Water could be a reasonable alternative to this water. It is the user’s responsibility to verify the suitability of the alternative water used.