Water scarcity and deteriorating water infrastructure are of growing concern in the United States. The conventional methods of treating and transporting potable water and wastewater are being challenged as new technology creates opportunities for water reuse. Instead of simply replacing the current infrastructure for centralized treatment systems, alternatives such as dual distribution and decentralized treatment systems are being investigated as more sustainable alternatives.
Implementing dual distribution systems leads to benefits such as reducing the amount of water treated to potable standards and reducing freshwater withdrawals. A dual distribution system allows the non-potable demands to be shifted from the potable water supply to a lower quality water source such as greywater, rainwater, or reclaimed wastewater. Removing demands such as fire flow, irrigation, laundry, and toilet flushing from the potable demand reduces the demand and allows potable water to be treated to higher water quality standards in a more efficient and cost effective way. A dual distribution system allows water to be treated to the levels necessary for the end use instead of treating all water to drinking water standards.
Before water reuse can be widely implemented, the infrastructure requirements for dual distribution need to be understood. Once the infrastructure requirements are known, they can be evaluated using economic and life-cycle analyses to determine the overall feasibility of the systems.
The infrastructure requirements are determined through the use of EPANET 2, a hydraulic model developed by the United States Environmental Protection Agency. Scenarios utilizing systems such as using untreated greywater for subsurface irrigation require the least amount of infrastructure. As the complexity of the system increases so does the required infrastructure. In this study, the infrastructure requirements are determined for the following scenarios: greywater and rainwater for non-potable use in single-family residences, rainwater for non-potable use in an apartment building, and reclaimed wastewater use in a community.