The utility model relates to a water quality monitoring technical field, and disclose a water quality monitoring water storage tank, the power distribution box comprises a box body, the top fixed mounting of box has a case lid, and the top right side fixed mounting of case lid has an outlet duct, and the bottom fixed mounting of case lid has a hydraulic stem, and the access door has been offered in the left side of box, and the left side fixed mounting of access door has a handle, the box comprises with the cabin that impounds operating chamber, and the fixed slot has all been seted up to operating chamber's left and right sides inner wall. This water quality monitoring water storage tank, through setting up the fixed slot, whether hydraulic stem and hydraulic board can contact the water in the retaining cabin if adjusting cleaning brush, when loading the water that needs the monitoring in the cabin that impounds, just be transferred to the motor operating chamber's top, just can makecleaning brush contactless to water, to not influence of quality of water, after the water detection of retaining in the cabin is intact, open the access door, adjust the hydraulic stem and spread out, make cleaning brush transfer to under -deck wall and the bottom of impounding, open the motor, just can clean the retaining cabin.