ASTM Water


© American Society for Testing and Materials



This specification covers requirements for water suitable for use in methods of chemical analysis and physical testing.

Four grades are specified:


Specifications by Water Type(I, II & III only)



Microbiological contamination: when bacterial levels need to be controlled.

Reagent grade water is further classified as: Type A Type B Type C Maximum heterotropic 10/1000 mL 10/100mL 100/10 mL bacteria count.  Endotoxin, EU <0.03 0.25.


The method of preparation of the various Grade(s) of Reagent Water determines the limits of impurities and shall be as follows:

Type I Grade of Reagent Water shall be prepared by distillation or other equal process, followed by polishing with a mixed bed of ion exchange materials and 0.2u membrane filter.  Feed Water to the final polishing step must have a maximum conductivity of 20 uS/cm at 25o C


Note: Because distillation is a process commonly relied upon to produce high purity Water, the levels specified for Type II Reagent Water were selected to represent the minimum quality of Water that a distillation process should produce.