Severe drought in the southeastern United States caused

the U.S. Environmental Protection Agency (EPA) to

address the need for water conservation and develop a

water management plan for their Science and Ecosystem 

Support Division (SESD). The water management plan 

aimed to reduce SESD’s potable water usage (more than

2.4 million gallons in fiscal year 2008) through an air

handler condensate recovery project. 

The EPA SESD encompasses 12 acres in Athens, Georgia.

A single laboratory building was constructed in 1996

consisting of 66,200 square feet configured for a mix use

of laboratory and office activities.

In May 2008, SESD completed an air handler condensate 

recovery system. The system routes condensate from

rooftop air handler units to the facility’s cooling tower,

reducing potable water usage and improving cooling tower 

water chemistry. 

Project Summary

The EPA Science and Ecosystem Support Division’s heating 

and cooling air handler units are located on the roof of the 

facility. During cooling, air passes through the chilled cooling 

coils in the three air handler units prior to entering the facility. Summer in Athens is hot and humid, causing condensate 

to form rapidly as air passes over the cooled coils. This 

condensate then drips into a collection pan below the unit. 

Air Handler Condensate 

Recovery at the

Environmental Protection 

Agency’s Science and 

Ecosystem Support Division 

Best Management Practice Case Study #14: 

Alternate Water Sources

EPA Science and Ecosystem Support Division: PIX 16721

Initial piping and the condensate collector next to one air 

handler unit

EPA Science and Ecosystem Support Division: PIX 16722

The collection manifold from each of the three units as the 

condensate is joined together

FEDERAL ENERGY MANAGEMENT PROGRAM

FEMP acknowledges the following EPA employees for supporting this 

program and case study: Betty Kinney, Dexter Johnson, Bucky Green,

and Karen Murray; and Holly Cannon of Eastern Research Group.

FEMP facilitates the Federal Government’s 

implementation of sound, cost-effective

energy management and investment practices 

to enhance the nation’s energy security and 

environmental stewardship.
At the same time, the cooling tower at SESD requires a 

generous amount of make-up water to replace water lost 

to evaporation. In its original design, the system allowed 

condensate to collect on the roof and drain with the other 

rooftop storm water, effectively wasting the nearly distilledquality condensate. 

EPA decided to let waste meet need. Pumping equipment and 

piping was installed from the air handler units to the nearby 

cooling tower. The piping directs water from the bottom of 

each air handler unit into a collection basin located next to 

each unit. When the collection basin fills to a specified level, 

pumping equipment moves recovered condensate from each 

unit over a brick dividing wall to join recovered condensate 

from the other two units. The recovered water then flows 

directly into the cooling tower located adjacent to the building, reducing the amount of potable water needed for cooling 

tower processes.

Since the project came online in May 2008, water condensate 

recovery rates during hot and humid conditions averaged 

approximately 120,000 gallons per month.

Cost and Savings Summary

EPA spent $24,500 on the air handler condensate recovery 

project. This cost included installation of a flow meter to 

measure total gallons recovered and directed to the cooling 

tower. From May through December 2008, the project saved 

EPA more than 540,000 gallons of water resulting in a 16 percent total reduction in SESD’s overall water use. This water 

savings is valued at $3,500 at a rate of $6.52 per thousand 

gallons of water. The system also improved cooling tower 

water chemistry and is expected to reduce overall chemical 

treatment costs due to the nearly-pure recovered water. EPA 

estimates a simple payback of less than six years based on 

savings recorded in the first year of operation. 

Additionally, SESD significantly reduced water consumption 

from fiscal years 2007 to 2008. In 2007, the water consumption baseline measured 3.4 million gallons. In 2008, that 

number measured 2.4 million gallons, marking a 25 percent 

reduction in water consumption.

Due to the success of the air handler condensate recovery 

project, EPA intends to implement the project at all facilities 

that fall under the same climate conditions. An additional 

EPA facility in Athens, Georgia, and facilities in Edison, 

New Jersey; Kansas City, Kansas; Houston, Texas; and Fort 

Meade, Maryland have already implemented similar projects. 

These combined projects save approximately 3.3 million gallons of water each year. 

Furthermore, EPA has identified similar opportunities at 

seven additional EPA facilities, where they expect to save 10 

million gallons of water annually. In fiscal year 2008, EPA 

reporting laboratories used approximately 157 million gallons 

of water. By implementing condensate recovery projects, EPA 

could reduce potable water consumption by nine percent.

Cooling Tower

AHU AHU AHU

Schematic of the air handler condensate recovery system

EPA Science and Ecosystem Support Division: PIX 16723

The cooling tower discharge point

Front page photo, top: Environmental Protection Agency Science and Ecosystem 

Support Division: PIX 16725

For additional information

please contact:

EERE Information Center

1-877-EERE-INF (1-877-337-3463)

www.eere.energy.gov/informationcenter

Printed with a renewable-source ink on paper

containing at least 50% wastepaper, including

10% post consumer waste.

Prepared by Pacific Northwest National Laboratory 

(PNNL) and produced by the National Renewable 

Energy Laboratory (NREL), both national laboratories 

of the U.S. Department of Energy Office of Energy 

Efficiency and Renewable Energy. NREL is operated 

by the Alliance for Sustainable Energy, LLC.

DOE/GO-102010-2930 • February 2010

SESD recovered approximately 540,000 gallons 

of water from May through December 2008, 

representing 16 percent of the facility’s total water use 

due to the air handler condensate recovery system.