Atmospheric Water Generation Technology
Evaluating the feasibility of technologies that produce potable water from the air
^J Technical BRIEF
www.epa.gov/research
INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
Producing Water from Air
Atmospheric water generators (AWGs) produce
potable water from surrounding air. This provides the
potential to expand water availability during shortages,
contamination events, and other issues that can
interrupt drinking water services. Natural disasters,
such as hurricanes, and public water infrastructure
failures, such as pipe corrosion resulting in
contamination issues, have increased the interest in
AWG technology as both emergency and long-term
supply solutions.
These generators range from home-based units that
can produce 1 to 20 liters of water per day to
commercial-scale units capable of 1,000 to over 10,000
liters per day. Water production rates are highly
dependent upon the air temperature and the amount
of water vapor (i.e., humidity) in the air. The most
commonly used AWG systems employ condenser and
cooling coil technology to pull moisture from the air in
the same way a household dehumidifier does.
Although significant quantities of energy can be
required to operate these condenser and fan systems,
recent technological advancements have substantially
improved the energy-water ratio—increasing the
feasibility of using these systems to help augment the
Nation's drinking water resources.
Cooperative Research Partnership
In September 2017, EPA's Office of Research and
Development announced a new Cooperative Research
and Development Agreement (CRADA) to further
advance the science of AWG and assess its potential as
a water production and supply solution. Specifically,
EPA signed a CRADA with Watergen to evaluate their
GEN-350 system. Watergen is a corporation developing
cutting-edge AWG technology. The GEN-350 can
generate nearly 600 liters of water per day in optimal
temperature and humidity conditions. A test unit was
evaluated at one of EPA's lab facilities for collaborative
research purposes.
EPA evaluated the microbial quality of untreated
condensate from a commercial atmospheric water
generator during a three-month study.
Research and Evaluation
Although high quality water is anticipated, volatile
organic compounds in the air can dissolve in the
condensate, providing a food source for microbial
growth in plumbing and stored water. An initial review
of water quality data provided by Watergen confirmed
both the generally high quality of produced water (e.g.,
no elemental analyses above current EPA drinking
water standards), and an elevated level of overall
microbial numbers, as defined by heterotrophic plate
counts (HPC). The HPC method provides an overall
estimate of colony forming heterotrophic bacteria in
water. Indicators of fecal contamination, such as fecal
coliforms and Escherichia coli, were not detected.
The goal of the research study under the CRADA was to
evaluate the microbial quality of untreated condensate
and produced treated water from a Watergen GEN-350
unit during three months of continuous operation. In
the absence of disinfection substances/system there
can be microorganisms as determined by HPC. These
microorganisms may not represent a direct human
health risk, but positive HPC results suggest favorable
conditions for microbial growth. The primary
microorganisms of human health concern are
opportunistic pathogens that can grow in drinking
water infrastructure, such as Legionella spp. and
Mycobacterium spp.
U.S. Eiivironmental Protection Agency | Office of Research and Development
EPA/600/F-19/129 November 2019

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Results and Conclusions
Neither Legionella nor Mycobacteria were detected in
weekly samples. However, EPA testing confirmed high
HPC results in both treated and untreated waters. All
test results indicated that the water produced by
Watergen's GEN-350 is microbiologically safe for
human consumption.
Watergen has acknowledged the need for further
disinfection to reduce the risk of microbial growth.
They offer a disinfection process unit as part of an
overall solution for the GEN-350 treatment train. The
unit is intended for long-term water preservation.
Contacts
Technical Contacts
•	Jay Garland, garland.jay@epa.gov
•	Michael Jahne, iahne.michael(5>epa.gov
Communications Contact
•	Michelle Latham. Iatham.michelle@epa.gov
Disclaimer: This document is for informational
purposes only. Any mention of or reference to
commercial products, processes, or services by trade
name, trademark, manufacturer, or otherwise does
not imply an endorsement by the U.S. Government or
the U.S. Environmental Protection Agency and shall
not be used for advertising or product endorsement
purposes. EPA does not endorse any commercial
products, services, or enterprises.
Additional Information
•	AWG Evaluation Report:
cfpub.epa.gov/si/si public record Report.cfm?d
irE n trvld=343997& L ab=NE RL
•	Watergen Information: watergen.com
•	EPA's Water Research: epa.aov/water-research
Evaluation of Atmospheric
Water Generation Technology:
Microbial Water Quality
U.S. Environmental Protection Agency Office ofResearch and Development

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