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Rainwater Collection Systems: A Money Saver for Commercial Buildings

The water crisis that is upon us now is as severe as and even more dangerous than the oil shortage currently plaguing our nation. Our cities are doing battle in court over rights and amounts of water drawn from shared sources such as lakes and rivers. Rain water harvesting is an ancient and viable solution to part of this problem since much of the water in use by the populace is not, in fact, drinking water but water used for lawns and bathrooms. The answer is literally falling from the sky, simply waiting to be utilized.

Cities Going Dry

Wahaso’s analysis of research done by the National Resources Defense Council and the Ceres group yielded a list of top ten cities in danger of going dry. Some of these were obvious, such as Houston, San Antonio, and Las Vegas, but others were far more surprising. Orlando, Florida and Atlanta, Georgia also made the cut due to the trifles of legal battles, as neighboring states and cities fight over use of the same water supply. Florida’s Aquifer is diminishing and a cap on the amount of water that the city of Orlando can pull for use would make sense. However, the Orlando’s population is growing so fast that a limit would cause severe water shortages for the city. Meanwhile Atlanta is fighting for the rights to draw water from Lake Lanier, a process which was made illegal in federal court as a result of the arguments from neighboring states.

Go Green, Save Green

Wahaso’s harvesting systems make it possible for commercial businesses to capture and use rainwater which can greatly reduce the amount of municpal water used. These systems can supply water for non-potable uses such as flushing toilets, which accounts for up to 65% of the total water usage in a commercial building. Average toilets use about 6.5 gallons per flush, with newer, more economic models using about 3.5 gallons per flush. Imagine the amount of savings available through these rainwater collection systems given the number of toilets each commercial building houses. It would leave more water for the city and more money the bottom line.

Steps Toward the Future

The importance of rain water collection is an idea that is spreading. For example, the Public Building Commission of Chicago created the Water Reuse Handbook, outlining the highly advanced system developed by Wahaso for the Harold Washington Social Security Building, which provides 800,000 gallons to the premises every year. Green building programs such as LEED are providing fantastic incentives by awarding points toward certification for water recycling . Cities looking toward a sustainable future need to consider incorporating more water reuse in order to conserve water and save money.

Add Water Harvesting to Your LEED Project to Achieve Gold & Platinum Levels

Many of our projects at Water Harvesting Solutions involve clients who are pursuing Leadership in Energy and Environmental Design (LEED) certification. This program, developed by the U.S. Green Building Council, provides an independent, third party evaluation of a building to determine if it meets optimum performance in five areas:

  • Sustainable site development
  • Water savings
  • Energy efficiency
  • Material selection
  • Environmental quality

Each performance area is assigned a set number of points which are accrued through meeting various criteria. These points are added up to determine if the building has achieved LEED certification. To certify a new building as “green” requires 40-49 points. More points are required to achieve the higher certification levels of Silver (50-59 points), Gold (60-79 points) and Platinum (80 points or more). Those higher certification levels almost certainly must include achievements in categories related to water conservation.

The water efficiency goals of the LEED program encourage smart water use both inside and outside of the building and can provide up to 12 possible points toward certification. In the area of Water Savings points can be accumulated in the following categories: 1) water efficient landscaping, 2) innovative wastewater technology and 3) water use reduction.

Harvested water can be a key component to obtaining LEED water savings points. For example, using captured rainwater or greywater for irrigation can provide points for the “water efficient landscaping” category. A 50% reduction of potable water for landscaping is worth two LEED points and a 100% reduction is worth four points. Water harvesting can also be used to gain two points in the “innovative wastewater technology” category. Reusing rainwater and greywater not only helps to reduce potable water consumption, but it also reduces the amount of water sent into the municipal storm system. Finally, up to four points can be awarded for overall water use reduction (irrigation is not included since it has a dedicated category.) A baseline for water usage is calculated for the building and the amount of points received corresponds to the amount of water saved:


  • 30% reduction from baseline = two points
  • 35% reduction from baseline = three points
  • 40% reduction from baseline = four points

Additionally, water harvesting can earn points in the area of Sustainable Site Development. Harvesting stormwater for reuse can earn one point for minimizing run-off and one point for reducing the amount of contaminants that enter the storm system.

Our most efficient systems often capture multiple sources of on-site water for multiple uses. So a single system might capture rainwater, greywater and condensate to flush toilets and irrigate landscaping, saving as much as 90% of the total municipal water an office building would otherwise use. These systems can earn points from all four categories and help boost a project into the Gold or Platinum point levels.
The benefits of LEED certification are both environmental and financial. Not only does reducing water consumption help to conserve a vital resource, but it also reduces costs for municipal water use and stormwater management. LEED certification is also shown to increase a property’s resale value, making the investment in a water harvesting system a winning proposition.

Kim Seay

Marketing Manager

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