A water treatment apparatus includes a tank, a driving unit, a filtered-water pipe, a filtering unit and at least one scraping unit. The tank includes a wall, an inlet pipe extending through an upper portion, and an outlet pipe extending from a lower portion. The driving unit is located on an external side of the tank. The filtered-water pipe extends throughout the tank and is connected to the driving unit. The filtering unit includes flat filtering bags located around the filtered-water pipe. The flat filtering bags can be spun together with the filtered-water pipe. The scraping unit includes scrapper assemblies each located between and in contact with two adjacent ones of the flat filtering bags.