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.

Many healthcare facilities are subject to the Centers for Medicare and Medicaid Services guidance that requires the facility to have water management plans. These plans draw on guidance from the Centers for Disease Prevention and Control and ASHRAE (ASHRAE 188)


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 Academy of Sciences convened an expert committee to review the state of the science related to the management of Legionella in water systems, formulate recommendations to improve management of Legionella contamination of water systems, and consequently better control Legionnaires’ disease in the United States.  The report was completed in August 2019 and is entitled Management of Legionella in Water Systems. In conjunction with this report, NAS also released interactive science-based guidance for facility managers

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.

Naegleria fowleri

Water utilities may see an increase in questions about Naegleria fowleri (nā-ˈglir-ē-ah fau̇(-ə)l er-ē) in the coming days, following the discovery of the commonly called "brain-eating amoeba" in potable water samples from a Texas water system.

The Texas Department of Environmental Quality, water supplier and affected community have responded through a series of actions, beginning late last Friday with a do-not-use order for eight communities and subsequent resolving to an active free chlorine treatment and flushing program for one community where preliminary positive samples were observed.

It is important to remember you cannot get infected from drinking water contaminated with Naegleria fowleri. Naegleria fowleri infects people when water containing the amoeba enters the body through the nose.

Learn more about CDC recommendations for protecting yourself from Naegleria fowleri.-contaminated water.

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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