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Ground Water and Drinking Water

Technologies for Legionella Control in Premise Plumbing Systems

The document below, Technologies for Legionella Control in Premise Plumbing Systems: Scientific Literature Review, provides information on the use and effectiveness of Legionella control strategies in premise plumbing systems.

This non-regulatory document provides technical information on Legionella control in premise plumbing in buildings. It can help states and facility owners/operators make better informed decisions on Legionella control. The document does not recommend any particular technology nor the installation of treatment. It does not address concerns related to Legionella risk associated with cooling towers.

Questions and Answers

What Legionella control measures does the document cover?

The document covers risk management approaches to address microbial (e.g., Legionella), physical and chemical risks in various parts of the premise plumbing system, such as water management programs, hazard analysis and critical control point and water safety plans. It presents information technical information on the following treatment technologies:

  • Chlorine
  • Monochloramine
  • Chlorine dioxide
  • Copper-silver ionization
  • Ultraviolet light
  • Ozone

For each technology, a summary of the reviewed studies is presented regarding its effectiveness against Legionella, potential water quality impacts that may result from using the technology, and operational considerations. The document also discusses other control technologies that are used for emergency remediation such as superheat-and-flush, hyperchlorination and point of use filtration.

Is EPA recommending a particular Legionella control technology?

EPA is not recommending any particular technology nor requiring the installation of treatment in premise plumbing systems to control for Legionella.

How does EPA protect my drinking water from Legionella in drinking water?

  • EPA regulates Legionella under the Surface Water Treatment Rule.  This rule applies to regulated public water systems. In addition, the Revised Total Coliform Rule and the Ground Water Rule have treatment technique requirements that address risks from bacterial contamination. These rules may also provide some control of Legionella
  • EPA is reviewing existing microbial regulations as part of the Six-Year Review process to evaluate the need to further improve protection against Legionella in regulated public water utilities. 
  • EPA does not regulate premise plumbing systems unless treatment is added to these systems.
  • Facility owners/operators who are considering adding treatment to their premise plumbing system are advised to consult with their drinking water primacy agency for any specific regulatory requirements that may apply before they add any treatment.

If there is an existing regulation, then why does there need to be additional advice from EPA about the use and effectiveness of control technologies in premise plumbing systems?

  • Premise plumbing systems are not typically part of the regulated water supply unless the facility owner/operator adds a secondary treatment system, and then is defined as a public water system. Premise plumbing systems in large facilities may have conditions that allow Legionella growth which could result in increased risks of disease.
  • Many facility managers have decided to take measures to control or mitigate Legionella in their buildings. Therefore, states have sought information to help these facility managers make science-based decisions about different ways to control Legionella in premise plumbing systems.
  • The document also provides information that will help individuals who decide to install treatment in their buildings understand potential water quality issues and other unintended consequences that could result due to failures in proper operation and maintenance of treatment systems.

Where can I find more information on developing Legionella-related risk management approaches?

Please see Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings.

Public Meeting and Webinar Information

On November 9, 2015, EPA held a public meeting and webinar to seek public input on the draft document.  

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