Casula consists of undulating, gently rolling land, with elevations across the suburb being mostly between 30 and 70 metres above sea level. The Georges River forms the eastern boundary of the Casula, and its western bank is paralleled by a relatively steep escarpment.. Casula is a suburb of Sydney, in the state of New South Wales, Australia. Casula is 35 kilometres south-west of the Sydney central business district, in the local government area of the City of Liverpool. Casula (is the first suburb immediately south of Liverpool on the Hume Highway and the Main Southern Railway between Sydney and Melbourne