This report documents the development and implementation of a flexible Individual Water Sample Quality Assurance (IWSQA) Program. The management of the data obtained from the chemical characterization of a water sample is described. These data are used to calculate the IWSQA ratios used to evaluate the data for possible errors and indications of which chemical constituents should be reanalyzed before reporting. The theory, definitions, tables for calculation, and guidelines for interpretation of the ratios are given. 13 refs., 3 figs., 10 tabs.