Abstract: A catch flow restrictor plate to control surcharging of water in a sewer system. The restrictor plate is to be placed in a catch basin and consists of a tray, which comprises an upper edge, downwardly sloping walls descending from the upper edge, the walls merging into a central portion. The central portion has a plurality of concentric calibration lines formed therein enabling to form an opening of a selected size by removing part of the central portion along a selected calibration line. A plurality of vertical fins are provided that radially extend from the central portion to the upper edge. The upper edge is arranged to hold the tray within a frame of the catch basin.