Abstract: A water filtration system includes a raw water line, a purified water line, and a plurality of water filtration units. The filtration units are connected in parallel between the raw water line and the purified water line. Each of the filtration units has a water filter disposed between and separating a raw water side of the unit connected to the raw water line and a purified water side of the unit connected to the purified water line. The raw water side of each unit has a drain opening. The system furthers includes a plurality of raw water valves each disposed between the raw water line and the raw water side of one of the plurality of units, a plurality of purified water valves each disposed between the purified water line and the purified water side of one of the plurality of units, and a plurality of drain valves each disposed to control flow through the drain opening of one of the plurality of units.