The purpose of this project was to examine the water quality of the pre-chosen 362 drinking water systems and 38 simple tap-water systems of the 22 municipal counties or cities. There were 48 analytes for drinking water systems.The regulated analytes included 13 metals (arsenic, lead, selenium, chromium, cadmium, barium, antimony, nickel, mercury, silver, indium, molybdenum and aluminum), 2 health affecting substance (cyanide, fluoride), 4 disinfection byproducts (total trihalomethanes (TTHMs), bromate, chlorite and haloacetic acids (HAA5) ), 15 volatile organics (trichoroethylene, carbon tetrachloride, 1,1,1-trichloroethane, 1,2-dichloroethane, vinyl chloride, benzene, 1,4-dichlorobenzene, 1,1-dichloroethene, dichloromethane, 1,2-dichlorobenzene, xylenes, cis- and trans- 1,2-dichloroethene, tetrachloroethene and toluene), 13 pesticides (endosulfan, lindane, butachlor, 2,4-D, paraquat, methomyl, carbofuran, Isoprocarb, methamidophos, diazinon, parathion, EPN, and monocrotophos) and 1 persistent volatile organic compound (dioxins), which accounted for a total of 48 analytes. 　　The total test counts of the regulated analytes for tap-water systems were 6741, and the total test counts of the regulated analytes for simple tapwater systems were 675 respectively. Water examined for all tested locations met the required drinking water criteria, which had a passing rate of 99.2% and 99.9%. All analytes tested met the required drinking water criteria, which had a passing rate all of 100.0%. 　　The results indicated the content of Total Trihalomethanes (TTHMs) exceeded the drinking water quality regulations include TTW-U01-1 which is one the distribution network of Cheng Kung water treatment plant in Penghu County, TTW-W04 (Sheng Li water treatment plant) in Lienchiang County; the content aluminum of exceeded the drinking water quality regulation include TTW-W04 (Sheng Li water treatment plant) in Lienchiang County, TTW-W05 (Chuis Hui Wo water treatment plant) in Lienchiang County. Focusing on concentration which exceed and approach the drinking water regulation in 2016, the results show that the aluminum concentration of TTW-W04 (Sheng Li water treatment plant) still exceed the drinking water regulation. The rest of the test location had improved since 2017

Drinking Water Quality Standards, Total Trihalomethanes, Aluminum