Rainwater Collection Could Save Urban Consumers $90 Million a Year

There’s a cheap, abundant resource that could help consumers save money and fight climate change: rainwater.

by Zachary Rybarczyk

Residents in eight cities around the U.S. could collectively trim up to $90 million a year off their water bills with simple rainwater collection techniques, according to a new report.

Urban rooftop rainwater collection, often overlooked or discouraged by complicated regulations in major cities and neighborhoods, could help individuals and families save money while improving water quality, says the Natural Resources Defense Council in a new report.

“Even under conservative assumptions, the study demonstrates that each city modeled can capture hundreds of millions to billions of gallons of rainwater each year, equivalent to the total annual water use of tens to hundreds of thousands of residents.”

And the yearly savings could be far greater for Americans than $90 million. The eight cities profiled in the NRDC analysis are only a snapshot of the different regions around the country.

Over 44 billion gallons of freshwater are used by public water suppliers on a daily basis in the United States, with consumers representing one of the highest individual daily usage rates in the world (between 100 and 165 gallons). As climate change and population growth drain some regional water supplies, urban dwellers may be vulnerable to water shortages or price spikes.

Much of the heavily treated, energy-intensive and perfectly drinkable water is wasted on tasks that could be used for non-potable supplies. For example, more than 11 percent of residential and 25 percent of commercial drinking water is spent on flushing toilets — over 2 trillion gallons a year.

NRDC has found that non-potable residential and commercial rooftop rainwater collection, which has been utilized in some regions of the US for some time to supplement residential outdoor activities, could be expanded to supply large cities with between 21 to 75 percent of their yearly water use.

The report lists four major benefits of capturing urban rainfall:

  • Inexpensive, on-site supply of water that can be used for outdoor non-potable uses with little, if any, treatment, or for a variety of additional uses including potable supply with appropriately higher levels of treatment
  • Reduced (or no) energy and economic costs associated with treating and delivering potable water to end users because capture systems often use low-volume, non-pressurized, gravity fed systems or require only the use of a low power pump for supply
  • Reduced strain on existing water supply sources
  • Reduced runoff that would otherwise contribute to storm water flows, a leading cause of surface water pollution and urban flooding

Lightly or non-treated, non-potable water, collected in rainwater basins, has the potential to replace nearly 80 percent of daily residential water usage (clothes washing, toilet flushing, and outdoor uses) that does not require drinking water.

Rooftop containment also has the potential improve water quality around metropolitan areas by preventing excess storm water (often filled with sewage, toxins, and chemicals that coat our sidewalks and streets) from washing into rivers, streams, and beaches. In fact, the EPA views urban runoff as “one of the greatest threats to water quality in the country,” and one of the leading causes of surface water pollution.

Unfortunately, rainwater collection is often hampered by overlapping and contradictory local regulations for non-potable indoor water use, which makes rainwater containment “overly complicated.” By addressing some of the simple rules than govern water use, rainwater collection could be a major factor in our ability to mitigate and adapt to climate change.