Abstract: A drainage device (1) for a waste water outlet (12) includes an outer tubular member (102) adapted to fit within the waste water outlet (12). An inner tubular member (103) is located within the outer tubular member (102). The interior of the inner tubular member (103) provides a first outlet and a second outlet is defined by the external wall of the inner tubular member (103) and the internal wall of the outer tubular member (102). A valve member (108, 109) is movably mounted with respect to the inner and outer tubular members (102, 103) for movement between a first position in which the second outlet is obturated and the first outlet is open to permit a liquid to flow therethrough, and a second position in which the second outlet is open to permit liquid to enter the second outlet.