Water suitable for use in making up reagents or for use in sensitive analytical procedures. There are several grades of reagent grade water as defined by various professional organizations such as ASTM, CAP, NCCLS, and ACS:1.Type I: Used for procedures requiring maximum accuracy and precision, such as atomic spectrometry, flame photometry, enzymology, blood gas, pH and specific ion determinations; reference buffer solutions; and reconstitution of lyophilized materials used as standards. ASTM to produce Type I water specifies distillation pretreatment of feedwater.2.Type II: Recommended for most analytical or general laboratory testing such as hematological, seralogical, and microbiological procedures as well as chemical methods not specifically stated or proven to require Type I quality. ASTM specifies preparation of Type II by distillation and recommends it whenever freedom from organic impurities is important.3.Type III: Satisfactory for some general laboratory tests; for most qualitative analyses such as urinalysis, parasitology, and histological procedures; for rinsing of analytical samples; preparation of stock solutions; and for washing or rinsing of glassware (final glassware rinsing should be performed with the water type specified for the procedure performed). Distillation, mixed-bed deionization, and reverse osmosis (with high quality feedwater) can be used to generate Type III.