By Maggie Haslam
Not all wastewater is the same. Yet in many cities, rain, greywater, and blackwater receive equal billing when it comes to treatment: all flow directly into municipal sewer systems. That’s why a team of University of Maryland students, faculty, and professional mentors designed WaterShed, their first place-winning entry in the U.S. Department of Energy Solar Decathlon 2011.
Though the primary objective of the Solar Decathlon is to challenge teams to build and operate solar-powered homes, WaterShed’s team saw the contest as an opportunity to take sustainable design a step further. With the nearby Chesapeake Bay, on the U.S.’s eastern seaboard serving as inspiration, the team made water conservation and reuse a priority, creating a sustainable home that is functionally and aesthetically in harmony with its environment while protecting and producing resources.
One of the team’s primary goals was to incorporate constructed wetlands into the design as a way to recycle rain and greywater. WaterShed’s design, successfully used for years in commercial installations, offers a compact version fit for a residential scale. WaterShed’s constructed wetlands allow the homeowner to harvest and reuse both rain and greywater for landscape irrigation and to support its on-site edible gardens.
It blends in seamlessly with the home’s architecture and landscape. There are other benefits, too. Recycling greywater minimizes impact on sewer systems, saving money, energy, and above all, water. Irrigating with water processed by constructed wetlands can reduce water usage by 30 to 50 percent a year.
WaterShed’s constructed wetlands resemble the natural marshes found in the Chesapeake Bay. They are effective water filtraters in all kinds of weather, including temperatures below freezing. The water harvested on site comes from two primary sources: storm water, which funnels directly from the home’s inward sloping roofs; and greywater from the bathroom shower and sink, which sit directly above the wetland beds. Water enters the wetlands, where native plants work with microorganisms to strip it of soap, pollutants, excess nutrients, and other pathogens. Once filtered, the water can be used for irrigation, stored for future use, or returned to the water table.
All of WaterShed’s irrigation water is recycled greywater from the home’s wetlands. Combined with compost made on site, it feeds over 15 types of fruit, vegetables, and herbs in the garden, as well as the surrounding landscape. This provides the homeowner low-cost and relatively low-maintenance access to fresh, organic food while controlling their impact on the environment.
This article originally appeared in Handshake: Food & PPPs, IFC’s quarterly journal on public-private partnerships. Handshake explores innovative and successful approaches by governments that are tapping the private sector to improve basic public services. Copyright © IFC, a member of the World Bank Group.