A drain box assembly for a convertible splash pad/ice rink structure comprises a housing having an open top and a closed bottom, sidewalls connecting the top and bottom of the housing in fluid sealing relation to form within the housing a vertically directed water flow channel that connects a water ingress port and a water egress port in fluid communication one with the other. Connectors operatively secure the housing at the water egress port to a drain pipe. A plurality of coolant pipe segments each have an axis of symmetry extending between a first open end and a second open end. The coolant pipe segments are mounted on the housing to extend through the vertically directed water flow channel adjacent the open top, in substantially transverse relation to the vertical water flow channel. The first and second open ends of each coolant pipe segment extend beyond the one or more upright walls.