This International Standard specifies the requirements and corresponding test methods for three grades of water for laboratory use for the analysis of inorganic chemicals. It is not applicable to water for organic trace analysis, to water for the analysis of surface active agents, or to water for biological or medical analysis. NOTE - For some purposes (for example for certain analytical methods or for tests in which the water is required to be sterile or pyrogen-free or of specified surface tension), additional specific tests and further purification or other treatment may be necessary.