PURPOSE: To enhance the ability to clean the city water below the water receiving tanks of buildings, apartment houses, etc., by constituting the water cleaning treatment device which passes the water through plural active carbon packed tanks connected in series after the ozone treatment of the water.

CONSTITUTION: Pipings are so connected that the water supplied from the lower part of an ozone treating tank 1 flows out of the upper part of the ozone treating tank 1 and is supplied to the lower part of an ozone treating tank 2. The active carbon tank is constituted by dividing the tank to two parts. The 1st active carbon tank 3 and the 2nd active carbon tank 4 are thus disposed. The water supplied from the lower part of the ozone treating tank 2 flows out of the upper part of the ozone treating tank 2 and is supplied from the lower part of the 1st active carbon tank 3. The water passes the inside of the active carbon packed tank of the active carbon tank 3, is filtered by a screen 8 and is supplied to the lower part of the 2nd active carbon tank 4; thereafter, the water passes the active carbon packed tank, then, the screen 9 and is supplied to and stored in a storage tank 6.