Thursday, March 22, 2018
Rainwater Harvesting: Recycling a Precious Resource

Rainwater Harvesting: Recycling a Precious Resource

by Pam Smith, North Carolina Sea Grant Program            

History is replete with accounts of ancient civilizations collecting and storing water for household and agricultural uses. The Romans engineered elaborate aqueduct systems to harness and convey rainwater to cisterns beneath the empire’s population centers. And the North American Anasazi channeled rainwater from mesa tops into stone-lined reservoirs.

Rain Cisterns

Rain Cisterns

Mike Halminski harvests rainwater for outdoor uses at his Outer Banks home. Photo Credit: Mike Halminski
These history lessons were not lost on nature photographer Mike Halminski. When he designed and built his Outer Banks, North Carolina, home decades ago, Halminski installed two 1,300-gallon cisterns for his household and darkroom needs.

Like Halminski, many backyard gardeners, developers and coastal community leaders are embracing harvesting rainwater from rooftops as an old idea whose time has come — again. Rain barrels and cisterns are becoming common sights in neighborhoods and at commercial, government and educational complexes.

“More and more, individuals and communities are thinking about sustainable water use,” says Gloria Putnam, North Carolina Sea Grant coastal resources and communities specialist. In October 2011, she co-organized a workshop that drew about 70 people to Onslow County to learn about rainwater harvesting and reuse strategies for communities.

“Harvesting rainwater is a water resource-saving measure — a way to cut demand for treating, transporting and using high quality drinking water for irrigation, vehicle washing and even street cleaning,” she adds.

During peak summer months, some estimates show more than 40 percent of water consumption goes to outdoor uses.

Tryon Palace Gardens

Tryon Palace Gardens

Kathy DeBusk and Mitch Woodward inspect Tryon Palace’s formal gardens that are irrigated by harvested rainwater. Photo Credit: Pam Smith
However, during a one-inch rain event, experts say it’s possible to harvest three-fifths of a gallon of reusable water from every square foot of roof. So it makes environmental and economic sense to collect, store and recycle rainwater from rooftops for an array of non-potable uses.

A 50- or 60-gallon rain barrel could capture rainwater year-round to satisfy part of a homeowner’s small-scale landscaping needs. Large capacity cisterns — suitable for greater outdoor uses — are available, but may require professional “how-to” guidance.

However, the extra effort to capture more “free” water pays double dividends: Rainwater harvesting helps protect water supplies and water quality.

In addition, cisterns can collect, store and filter stormwater on site. Contaminants carried in fast-moving stormwater are thereby prevented from reaching nearby streams, rivers and coastal waterways.

“There is room for innovation by folks looking to adopt site-specific, low impact development practices,” Putnam says.

Kathy DeBusk, a doctoral candidate in North Carolina State University’s Department of Biological and Agricultural Engineering, is working to design and install automated systems to manage stormwater and provide irrigation in public spaces. DeBusk is tracking progress of a sophisticated rainwater harvesting system she designed and installed for the visitors’ center at the entrance to Tryon Palace, in New Bern, NC, that includes five 650-gallon cisterns.

The harvested rainwater is used to irrigate gardens at the rear of the building. Overflow runs into an adjacent rain garden with moisture-loving, native plants.

Sophisticated electronics measure rainfall, check the National Weather Service rain forecast, and determine how much water will flow to the gardens.

“It’s an important part of a holistic waste-not, want-not approach that adds up to saving potable water and energy, recharging groundwater, and preventing stormwater runoff," Putnam concludes.

Those interested in learning more about rain barrels and other stormwater management resources can contact their state Sea Grant program as well as university or cooperative extension experts. For the full version of this story, please visit:

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