Commercial Rainwater Harvesting

Typical Uses for Rainwater in Commercial Buildings


Often, commercial landscaping has an irrigation system, but it isn't used because of the cost of water. What if water was free? How much would a lush landscaping improve sales? Raise property values?

In many areas, stormwater management requirements can be fulfilled using rainwater harvesting. Yes it costs more than the cheapest methods. But what is the payback on a retention pond?​

Cooling Tower Makeup

In Georgia, cooling towers us about 7 gallons per square foot of conditioned space every year. What if that water was free? If your building is 9 stories or smaller, it can be. An additional benefit in some areas: the water is mineral-free, which can reduce water consumption.

Here again, rainwater harvesting as stormwater management is the only method with any sort of financial return. Designed right, the additional cost for rainwater harvesting will pay for itself many times over before the warranty expires. Add to that the extra resale value, and we see financial returns of 25% annually, year after year.

Vehicle Wash

Same as residential, washing vehicles with rainwater is BETTER than with city water. Spot free wash! In most cases, the adjacent garage provides more than enough water.

Toilet Flushing

Rainwater harvesting for toilet flushing meets LEED criteria for water efficiency, without the concerns of ultra low-flow and waterless fixtures. Treatment increases, both to keep the flush valves from sticking and because we are used to sparkling clear odor-free water in our toilets. Plumbing piping requirements go up.

Potable Rainwater in Commercial Buildings

It's possible. The challenges here are more regulatory than technical. When a building owner chooses to use water other than municipal, it becomes a Public Water System, subject to Georgia EPD regulations. If this sounds intimidating it shouldn't; state parks and other rural developments fall under the same requirement. Reporting can be affordable and automated.

Other Alternative Water Sources

Ground Water

Ground water is some of the highest quality water available, and if available in sufficient quantity is a valuable resource.

Read about how this building is using groundwater, instead of paying $0.02/gallon to pump it into the overloaded sewer


When cooling an office, condensate from the air handlers will equal about 25% of the water needed for cooling tower makeup. And it's cool water, so even better for the towers. No treatment required!

Gray Water

In the industry, this means water that has been used on-site once already, but is cleaner than "black water." Common sources are showers, handwash sinks, laundry, and vehicle wash area runoff. Treatment methods vary, depending on the expected pollutants. NSF 350 is a new standard, designed to provide third-party certification for gray water treatment. There are 2 levels: residential and commercial.