Wastewater, also known as sewage, refers to used water that has been discharged into the drains of households and businesses. Wastewater contains microbiological and chemical hazards that have the potential to cause harm to people and the environment if not adequately managed.

The Department for Health and Wellbeing (DHW) administers the South Australian Public Health Act 2011 and the South Australian Public Health (Wastewater) Regulations 2013 to prevent and manage public health risks associated with human wastewater through the development and administration of policies, prescribed codes and approvals for wastewater collection, treatment, reuse, and disposal. Refer to wastewater legislation for further details. 

In South Australia, wastewater is managed by either a reticulated wastewater system or an on-site wastewater system.