Sadleir is an established residential area. Sadleir is bounded by Mannix Park in the north, Sadleir Avenue in the east, Cabramatta Creek in the south and Heckenberg Avenue in the west. Sadleir is named after Richard Sadleir, the first Mayor of Liverpool.

Development of the area dates primarily from the 1960s, as part of the Green Valley public housing area. The population has declined slightly since the early 1990s, a result of little change in dwelling stock and a decline in average household size.

Major features of the area include Eureka Creek Reserve and one school.