Scott McFarlaneEarth’s Manager of Ark Angel Pty. Ltd. [email protected]19th of October, 2011 ABSTRACT The important role that onsite sewage systems play in the development of townships and the current poor state of designing and managing onsite sewerage systems for townships is highlighted for review. In this paper’s review of this problem, a desktop study using 3 balance models is used to characterise and design sustainable onsite sewage systems for 11 Victorian and 8 other Australian townships. This information in turn is used to determine minimum subdivision lot sizes in a spatial and deep infiltration balance model. It is concluded that if designed and managed properly, onsite sewage schemes are still physically and economically feasible (e.g. 3-4 times cheaper per allotment than current Victorian practice) for the planned development of townships at the highest practical low risk environmental and public health integration standards, e.g. equivalent to that obtained by municipal wastewater reuse schemes.