Abstract: A drainage fitting (10) is described. The drainage fitting (10) comprises a housing (12) adapted to be inserted into a drainage outlet, the housing defining a housing inlet (14) and a housing outlet (16) and a one way valve (18) adapted to be received within the housing (12). The one way valve (18) has a body defining a valve inlet (22), a valve outlet (24) and a valve passageway (26), the passageway (26) providing fluid communication between the housing inlet (14) and the housing outlet (16). The drainage fitting (10) further comprises a fitting insert (28) adapted to be located in the housing inlet (14), the fitting insert (28) defining an insert portion (30) adapted to extend through the valve inlet (22) and into the valve passageway (26).