Purification processes required to reduce contaminant levels by different amounts

Purification processes based upon required reduction ratios. Appropriate purification processes are selected using the maximum reduction ratio for each contaminant group. For the example given in this table, Group A requires reverse osmosis (reduction ratio of 9.5 for fluoride); Group B requires no treatment (reduction ratio of 0.5 for mercury); Group C requires reverse osmosis or deionization (reduction ratio of 4.0 for aluminum); Group D requires softening, with or without reverse osmosis, or deionization (reduction ratio of 31 for calcium); and Group E requires carbon filtration (reduction ratio of 21 for total chlorine). This list can then be used to select a final purification cascade.