A manifold for connection to a medical/surgical waste collection unit, the waste collection unit having a receiver for receiving the manifold, a valve unit integral with the waste collection unit for regulating fluid flow from the manifold to a canister (36, 38), the valve unit being a valve disc formed with a cylindrical boss positioned to be engaged by a manifold opening and functioning as a drive member to rotate the valve disc to an open state, said manifold comprising: a housing (158, 164) comprising a shell of cylindrical shape and a cap with a cylindrical tube-shaped skirt, the housing (158, 164) dimensioned to fit in and rotate in the waste collection unit receiver and having: a void space, a circular base that forms a proximal end of said housing shell; an axis that extends distally from said base around which the housing rotates when in the waste collection unit receiver; and an outlet opening in the base through which fluid can flow from the void space into the canister of the waste collection unit; and at least one fitting attached to the housing (158, 164) so as to extend from the cap, the fitting dimensioned to receive a suction line, wherein the at least one fitting opens into the void space of the housing (148, 164), wherein the outlet opening of the manifold housing (158, 164) is adapted to function as a keyhole for receiving the valve disc boss of the valve unit of the waste collection unit, and said manifold outlet opening is located off center to the axis of the manifold housing (158, 164) so as to rotate with the housing and selectively open/close the valve unit of the waste collection unit when the manifold is rotated in the waste collection unit receiver with the valve disc boss received in the manifold outlet opening; and two tabs (222, 224) extend outwardly from a proximal end base of the manifold housing cap skirt, said tabs (222, 224) being diametrically opposed and subtending different arcs so that said tabs, when in registration with complementary slots (118, 120) formed in a lock ring attached to the waste collection unit receiver, align said manifold outlet opening with the valve disc boss. a housing (158, 164) comprising a shell of cylindrical shape and a cap with a cylindrical tube-shaped skirt, the housing (158, 164) dimensioned to fit in and rotate in the waste collection unit receiver and having: a void space, a circular base that forms a proximal end of said housing shell; an axis that extends distally from said base around which the housing rotates when in the waste collection unit receiver; and an outlet opening in the base through which fluid can flow from the void space into the canister of the waste collection unit; and at least one fitting attached to the housing (158, 164) so as to extend from the cap, the fitting dimensioned to receive a suction line, wherein the at least one fitting opens into the void space of the housing (148, 164), wherein the outlet opening of the manifold housing (158, 164) is adapted to function as a keyhole for receiving the valve disc boss of the valve unit of the waste collection unit, and said manifold outlet opening is located off center to the axis of the manifold housing (158, 164) so as to rotate with the housing and selectively open/close the valve unit of the waste collection unit when the manifold is rotated in the waste collection unit receiver with the valve disc boss received in the manifold outlet opening; and two tabs (222, 224) extend outwardly from a proximal end base of the manifold housing cap skirt, said tabs (222, 224) being diametrically opposed and subtending different arcs so that said tabs, when in registration with complementary slots (118, 120) formed in a lock ring attached to the waste collection unit receiver, align said manifold outlet opening with the valve disc boss.