Professional Practice

Improving Water Efficiency: Residential Water Recycling

Water collected on-site and stored in a 42,000 gallon cistern buried under the driveway. The water is used throughout the summer to replenish the pond to the left, as well as the fountains and irrigation for the plants. ASLA 2016 Professional Residential Design Honor Award. Water Calculation and Poetic Interpretation, Monterey Cypress, California / Arterra Landscape Architects

Recycled water is treated wastewater that can be used for landscapes. There are multiple grades of recycled wastewater. Greywater is domestic wastewater from kitchen sinks, dishwashers, and washing machines, and may include household cleaning products and food particles. Blackwater refers to water used in toilets that contains human excrement. In total, 50 to 80 percent of water used in homes is recyclable. Greywater, and even blackwater, can be diverted and treated through a filter system and then further used to irrigate residential, commercial, and agricultural landscapes.

Decentralized greywater systems, which are installed at or near the point where wastewater is generated, can supply up to 50 percent of landscape irrigation needs. Currently, however, reused water accounts for less than 1 percent of water used in the U.S., according to the National Academy of Sciences, due in part to concerns over safety of using reclaimed water for domestic purposes.

Depending on the extent of treatment, recycled water can be cleaner and safer to use than tap water. In an effort to maximize the use of recycled water, the city and county of San Francisco’s Recycled Water Ordinance requires property owners located within a designated area to install recycled water systems in new construction, modification, and remodeling projects. Each state has a set of specific regulations on the use of recycled water use, and some states require permits. Using recycled water can significantly reduce residential water waste, and therefore energy use and greenhouse gas emissions.

Source: Household Waste Water Recycling Systems, Green Living; “Water Reuse: Potential for Expanding the Nation’s Water Supply Through Reuse of Municipal Waterwaste,” National Academy of Science, 2012

Organizations

Australian Water Association

Greywater Action

National Onsite Wastewater Recycling Association

Water Reuse Association

Research

“The Water-Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape,” Laura Allen, Storey Publishing, 2015

“The New Create an Oasis with Greywater 6th Ed: Integrated Design for Water Conservation, Reuse, Rainwater Harvesting, and Sustainable Landscaping,” Art Ludwig, Oasis Design, 2015

Vegetated greywater treatment walls: Design modifications for intermittent media filters, Lindsey E. Svete, Norwegian University of Life Sciences, Department of Mathematical Sciences and Technology

“Water Reuse: Potential for Expanding the Nation’s Water Supply Through Reuse of Municipal Waterwaste,” National Academy of Science, 2012

Resources

Grey Water Policy Center

Israel Bets on Recycled Water To Meet Its Growing Thirst, NPR

From Drain to Drink: Innovations in Wastewater Reuse, Greenbiz

From Wastewater to Drinking Water, Earth Institute, Columbia University

Government Resources

Water Recycling, San Antonio Water System

Greywater and Wastewater, Australian Government

Groundwater Replenishing System, Orange County Water District, California

Water Recycling at Napa Sanitation District

Recycled Water Program, City of San Diego, California

Recycled Water Use in the Landscape, Government of Canada

Waste Water Systems, Department of Planning and Development, City of Berkeley, California

Water Recycling and Reuse: The Environmental Benefits, U.S. Environmental Protection Agency

Guidelines for Alternative Water Sources: Indoor and Outdoor Non-Potable Uses, Los Angeles County Department of Public Health

Projects

Silo House
Cornell University  

DBX Ranch, Pitkin County, Colorado
Design Workshop, Inc.

Water Calculation and Poetic Interpretation, Monterey Cypress, California
Arterra Landscape Architects

Urban Spring, San Francisco
Bionic San Francisco

Catalina Foothills, Tucson, Arizona
Design Workshop, Inc.