Determination of the minimum reduction required for each contaminant

Organization of water contaminants (second column) in the ANSI/AAMI/ISO standard (fourth column) into five groups (A-E, first column) based upon similarities in the methods required for their removal. Once the expected maximum feed water concentration of each contaminant has been estimated by direct measurement in combination with information from the water supplier, the values are entered in the third column of the table (feed water concentration [mg/L]). The necessary minimum level of reduction for each contaminant is then calculated by dividing the feed water concentration by the ANSI/AAMI/ISO standard concentration, and this value is entered into the fifth column (reduction ratio). The maximum reduction ratio for each group is found and entered in the sixth column (maximum group reduction ratio). These values are used to select appropriate water treatment processes.