Lonsdale is an industrial suburb south of Adelaide, South Australia, within the City of Onkaparinga.
Lonsdale was farmed from shortly after European settlement until the 1950s, when the South Australian Housing Trust acquired much of the land for industrial use. Mobil's Port Stanvac Refinery and Chrysler's engine foundry were followed by many other manufacturing and service industries. Subsequent suburban development of surrounding areas has driven demand for a wide range of service-oriented businesses in the area.
Port Stanvac Refinery and the Mitsubishi (formerly Chrysler) engine plant closed in 2004, with both sites remaining unused as of 2007. The South Australian Government announced plans to build a seawater desalination plant at the site in 2007, to provide fresh water for Adelaide. The Adelaide Desalination Plant opened in 2013.