An extensive study of commercially available home water treatment units has been conducted over a 3-year period to examine organics reduction and microbiological factors. The Phase 3/Final report provides a summary of Phase 1 and 2 results as well as detailed reporting of Phase 3. Phase 3 included the testing of 10 selected activated carbon units against a ground water spiked with carbon tetrachloride, trichloroethylene, tetrachloroethylene and 1,1,1-trichloroethane and of the same units against a surface water spiked with the above and with p-dichlorobenzene, hexachlorobenzene and chlordane; field studies (Miami, Fla.; Pico Rivera, Calif.; Atlanta, Ga.; and Detroit, Mi.) on four units; home tests on three units; bacterial leaching studies; spent carbon studies; and studies of limited value on four other units (reverse osmosis, ozonator, ultraviolet). Test data on two distillers had to be discarded because of technical problems.