Study in Progress
On-site Reuse of Graywater and Stormwater: An Assessment of Risks, Costs, and BenefitsWater Science and Technology Board
Statement of Task
An ad hoc committee will conduct a study and prepare a report that will analyze the risks, costs, and benefits of on-site water reuse of stormwater and graywater and approaches needed for its safe use. The study will address:
1) Quantity and suitability. How much on-site stormwater capture and graywater reuse occurs in the United States and for what applications? How would significant increases in stormwater and graywater reuse affect water demand and downstream water availability? What is the suitability--in terms of water quality and quantity--of captured stormwater and graywater for various purposes? What are the legal and regulatory constraints on the use of captured stormwater and graywater? What research should be pursued to understand these issues adequately?
2) Treatment and storage. What are typical levels and methods of treatment and storage for on-site stormwater capture and graywater reuse for various applications? What types of treatment are available at a household level to address contaminants and pathogens, and how do these treatment methods compare in terms of cost and energy use? What research opportunities should be pursued to produce improved technologies and delivery?
3) Assessing risks. What are the human health and environmental risks of using on-site captured stormwater and graywater for various purposes? What existing state and regulatory frameworks address on-site stormwater and graywater reuse, and how effective are they in assuring the safety and reliability of these practices?
4) Assessing costs and benefits. What are the costs and benefits of on-site stormwater and graywater use (including nonmonetized costs and benefits, such as effects on water and energy conservation and on wastewater infrastructure)? How do the economic costs and benefits generally compare with other supply alternatives? Can cost improvements be achieved through research?
As part of its review, and to help benchmark U.S. standing worldwide, the committee will consider international experiences in onsite stormwater and greywater management, as it deems relevant.