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Microbial (Pathogen)/Recreational Water Quality Criteria

EPA develops criteria to protect people from microbial organisms (sometimes referred to as pathogens) such as bacteria and viruses in water bodies (e.g., lakes, rivers, beaches).  Pathogens can make our waters unsafe for humans. Swimming and other recreational activities in water contaminated with pathogens can make people ill. People can also become exposed by drinking untreated water from contaminated water bodies.

EPA recommends criteria for limiting microbial organisms in water bodies to protect human health. State and tribal governments can use the criteria as guidance when setting their own water quality standards to protect human health.

On this page:

Recreational Water Quality Criteria


Draft Human Health Recreational Ambient Water Quality Criteria and/or Swimming Advisories for Microcystins and Cylindrospermopsin

EPA has issued draft recreational water quality criteria and/or swimming advisories for the cyanotoxins microcystin and cylindrospermopsin. EPA has identified draft recommended concentrations of the cyanotoxins to protect human health while swimming or participating in other recreational activities in and on the water. Once final, states can consider adopting these criteria into their water quality standards and using them for Clean Water Act purposes. Alternatively, states can use these same values as the basis of swimming advisories for public notification purposes at beaches. The draft criteria and/or swimming advisories are based on peer-reviewed, published science and methods. EPA is also providing information on the latest science on human health effects from exposure to cyanotoxins, discussion of other governmental guidelines for recreational waters, and information on incidents involving exposure of pets and other animals to cyanotoxins. On December 19, EPA announced the availability of the draft document and opened a 60-day public review and comment period to solicit scientific views, data, and other information. In response to stakeholder requests, the comment period will be extended for an additional 31 days, from February 17, 2017 to March 20, 2017.


Development of Recreational Water Quality Criteria for Coliphage

2016 Coliphage Experts Workshop

EPA held a Coliphage Experts Workshop in March 2016 as part of EPA’s ongoing efforts to build the scientific basis for developing coliphage-based water quality criteria.  EPA convened a group of twelve internationally recognized experts on the state of the science of coliphage and their usefulness as a viral indicator for the protection of public health in recreational waters. Experts represented a spectrum of perspectives from academia, federal agencies (EPA, CDC, FDA), and the wastewater industry. Agenda discussion topics included: the need for a viral indicator; coliphage as a predictor of gastrointestinal illnesses; how coliphage may be useful as an indicator of wastewater treatment performance; male-specific vs somatic coliphage; a systematic literature review of viral densities; and future research. The Coliphage Experts Workshop Proceedings document details the topics and overall findings from the Workshop. Additionally, the document provides the experts’ written responses to charge questions provided prior to the Workshop. The Proceedings document was recently peer-reviewed.

Review of Coliphages as Possible Indicators of Fecal Contamination for Ambient Water Quality

This is a literature review of the scientific information that EPA will evaluate to develop coliphage-based ambient water quality criteria for the protection of swimmers.  It generally indicates that coliphages are equally good indicators of fecal contamination as EPA’s currently recommended criteria for E. coli and enterococci. In addition, coliphages are better indicators of viruses in treated wastewater than bacteria. While EPA conducts its evaluation of coliphages as possible viral indicators for water quality, we continue to recommend that states adopt our 2012 recreational water quality criteria into their water quality standards. 


Drinking Water Regulatory Support Documents for Microbials

Criteria documents and guidance for drinking water contaminants provide information so preliminary decisions can be made as to whether the contaminant is a significant health threat via drinking water exposure and whether sufficient data exists to perform quantitative risk assessments.

Criteria documents and guidance for surface waters on this page provide information to help states adopt water quality standards that protect the health of people who recreate in water.


Water Quality Standards and Implementation


Drinking Water Health Documents

Health Advisories serve as informal technical guidance to assist federal, state, and local officials responsible for protecting public health when emergency spills or contamination situations occur. They are not to be construed as legally enforceable federal standards. The Health Advisories are subject to change as new information becomes available.

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