A stirring device is adapted to be used for a water storage system. The stirring device includes a tube unit and a stirring unit. The tube unit includes a rigid tube member, and a flexible tube member adapted for interconnecting the rigid tube member and an inlet of the water storage system. The stirring unit includes a center rod extending rotatably into the rigid tube member along an longitudinal direction of the rigid tube member, a support subunit positioning the center rod within the rigid tube member, a driver fan subunit mounted to the center rod and adapted to be driven by water for actuating rotation of the center rod, and a stirring member mounted co-rotatably to the center rod and adapted for stirring sediments in the water.