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Charles Haas works with American Water on WateReuse Research Grant

March 20, 2013

Civil, Architectural, and Environmental Engineering Department Head Dr. Charles Haas will be working with American Water on a recent research grant funded by the WateReuse Research Foundation to develop risk management strategies for Legionella in reclaimed water systems. The project is titled: Development of a Risk Management Strategy for Legionella in Recycled Water Systems.

Reclaimed water is former wastewater that is treated to remove solids and most impurities and is commonly used as recycled water for irrigation or to recharge groundwater aquifers.  Reclaimed water can also be used for cooling towers, water features, pools, spas, and as a non-potable supply water, all of which might provide venues to harbor Legionella, and subsequently serve as means by which people may become exposed.  Legionella is a pathogen that can cause significant respiratory problems and other complications when it is inhaled as a water aerosol.  Legionella pneumophila is the predominant species responsible for both Legionnaire’s disease and Pontiac fever.

Researchers intend to come to a more comprehensive understanding of the occurrence of Legionella within reclaimed water systems.  The public health importance of Legionella in both drinking and recycled water needs to be determined.  Dr. Haas will work with American Water’s Dr. Mark LeChevallier (Director of Innovation and Environmental Stewardship at American Water), Dr. Zia Bukhari and Dr. Patrick Jjemba, both also at American Water.  The Drexel focus will be on comparing the risks from reclaimed water used in various contexts to the risk when potable (city) water is used in those contexts.  Dr. Haas will be assisted by a doctoral candidate in environmental engineering, Kerry Hamilton.  American Water will be amassing useful data for this comparative risk assessment.  The end result will lead to a determination about what circumstances provide minimal additional risk relative to potable water use from Legionella. 

Professor Haas noted “I am gratified that yet another application for quantitative microbial risk assessment, which I have been developing for 30 years, is receiving attention and finding adoption in engineering better public health protection and sustainability.”

The intended outcomes of this research are to ensure that risk is minimized, public confidence remains for using recycled water for appropriate applications, and management recommendations are developed for users of recycled water. 

About the WateReuse Research Foundation
The WateReuse Research Foundation is an educational, non-profit public benefit corporation that serves as a centralized organization for the water and wastewater community to advance the science of water reuse, recycling, reclamation and desalination. The Foundation sponsors applied research which addresses the full range of scientific, technical, policy, and social science issues related to water reuse and desalination. For more information, visit

About American Water
Founded in 1886, American Water is the largest publicly traded U.S. water and wastewater utility company.  With headquarters in Voorhees, N.J., the company employs approximately 6,700 dedicated professionals who provide drinking water, wastewater and other related services to an estimated 14 million people in more than 30 states and parts of Canada. More information can be found at

Sarah Colins
Research Development Coordinator
Civil, Architectural, and Environmental Engineering