Waterborne Pathogens

Viral, Bacterial, and Parasitic Pathogens


A goal of drinking water and wastewater treatment is to reduce the numbers of viable organisms to acceptable levels, and to remove or inactivate all pathogens capable of causing human disease. Despite the remarkable success of water treatment and sanitation programs in improving public health, sporadic cases and point-source outbreaks of waterborne diseases continue to occur. Waterborne pathogens include the microorganisms Giardia, Cryptosporidium and Legionella.


Legionella is currently the leading cause of US waterborne disease outbreaks but is still believed to be under-reported. Legionella is different from typical waterborne pathogens in that the route of exposure is inhalation rather than ingestion.

The National Academies of Sciences, Engineering, and Medicine's expert panel on managing Legionella in water systems has just begun an 18-month effort to evaluate the state of the science of Legionella risk management from drinking water supply source to use, for example, showerheads, water fountains, hot tubs, or cooling towers. The panel was organized through a joint effort by the Veterans Administration, the US Centers for Disease Control and Prevention, and the US Environmental Protection Agency.

U.S. Centers for Disease Control recently distributed a new Legionella guide

Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings. This guide features a checklist to help building owners and managers identify where Legionella could grow and spread in a building and ways to reduce the risk of contamination. Information on how events outside of buildings can lead to Legionella growth, such as construction, water main breaks and changes to municipal water quality is also included.

AWWA recommends that utilities familiarize themselves with the guide and share it with relevant customers.

AWWA Manuals of Practice

You may also search decades of articles on this or other topics published in the Journal AWWA and Opflow.


2020 Water Quality Technology Conference, November 15-19, Schaumburg, Illinois (Northwest Chicago suburbs)

eLearning and Training


AWWA Policy Statements

AWWA's policy statements are brief statements on protecting and improving water supply, water quality, management, and the interests of the public and the environment. They are written by consensus, subject to review and comment by AWWA committees, councils, and members. Because they represent AWWA's position on these matters, they are approved by the AWWA Executive Committee of the board of directors.

Technical Committee Engagement

AWWA members are recognized globally for their industry expertise and their generosity in sharing that expertise for a better world through better water. AWWA members participate in committee activities, developing conference programs, writing technical manuals, developing standards, creating educational content and contributing to AWWA publications. Committee members primarily interact through conference calls, emails, and face to face meetings at conferences and events. More information on volunteering for an AWWA committee.

The following committees are active in addressing issues about waterborne pathogens


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