At least three different ways to use recycled water are applied around the world: groundwater and aquifer replenishment, surface water augmentation and direct potable reuse. Barriers to the installation of new recycling schemes tend not to be technical but arise from other parameters including the ‘yuck factor’; peoples emotional response to the prospect of drinking recycled sewage even though it is highly treated, clarified and safe. Both indirect (eg surface water augmentation) and direct potable reuse have advantages to utilities which include reduced overall energy requirements, construction and operational costs. Despite this, utilities find it difficult to assess the relative costs and benefits of various water reuse options. This research developed a Water Supply Evaluation tool (WaterSET) which is build on a MatLab platform but does not require a license to operate through its user-friendly Excel spreadsheet interface. It uses a comparison model which incorporates analysis of economic and scheme lifecycle costs, as well as environmental and social impacts. WaterSET generates a multi-criteria decision analysis that enables utilities to select the best recycling and reuse option for their own situation and customer base.

In an earlier project stormwater was collected from an urban environment, treated through electrolysis, injected into and retrieved from an aquifer, and reused for greywater irrigation. This research used the previously established hardware and software for ten months to gather data about operational efficacy, reliability and costs. E. coli, a common indicator of faecal contamination, was barely removed by electrolysis, and other pathogens were not examined, which prevents assessment of water quality or its compliance with the AGWR. 20878 kL stormwater were treated and added to the aquifer, and 5886 kL retrieved for irrigation. Total operational costs were $29344 and the cost of processed water ranged from $0.13 to $0.28 per kL. The purpose-designed software and computerised telemetry was reliable and suitable for upgrading with security features. It was concluded that the system has potential for further development as an alternative to using mains potable water to irrigate open public spaces.

Recycling wastewater by using reverse osmosis (RO) and ultrafiltration appears to be associated with the formation of some groups of micropollutants but there is not much information about these processes. This research selected iodinated disinfection by-products (DBPs) and N-nitrosamines (NDMA), and benzotriazoles and benzothiazoles, which are compounds in dishwasher detergents, for further investigation. It was concluded that minimising the formation of dichloramine (a precursor molecule to NDMA formation) by reducing pH and maximising activated sludge ammonia production, reduced the formation of N-nitrosamines in RO-treated wastewater. Iodinated DBPs and benzotriazoles were detected in RO treated wastewater in this study but at lower concentrations than those thought to pose a risk to human health.