A check valve (10) for controlling a flow of fluid by fluid pressure, comprising a housing (11) and a resilient flexible valve element (12) inside the housing (11), wherein the valve element (12) is formed as a hollow and longitudinally tapered body (16) with an open wide end (18) and a closed narrow end (19), and wherein the wide end (18) of the valve element (12), in a default configuration, engages an inner surface of the housing (11) to close the check valve (10) and is deformable by a predetermined fluid pressure from the inlet (13) to open the check valve (10). The tapered body (16) comprises a radially outwardly projecting flange (17) at the wide end (18), which flange comprises a curved outer surface portion (20) having a degree of curvature of 85 to 95 degrees, wherein the housing (11) is formed with a protrusion (29) having a curved surface (30) for engaging the curved outer surface portion (20) of the flange (17).