A water filtering device includes a casing having a first space defined therein and an inner part is received in the first space. The casing includes an inlet at top thereof and an outlet at a lower end thereof. The inner part includes a cover and an inner tube is located therein. A second space is defined between the inner tube and the inner periphery of the inner part. Filtering particles are received in the second space. The inner part includes apertures defined through a lower end thereof and communicating with the first and second spaces. Water enters into the first space form the inlet and enters into the second space via the apertures and is filtered by the filtering particles. The filtered water flows over the open top of the inner tube and enters into the inner tube and flows out from the outlet of the casing.