Mineral Oxychloride: A Continuous Disinfection Method for Legionella Control in Healthcare Water Systems

Abstract

Tony Tanner*

Legionella colonization in healthcare and long-term care facility water systems continues to pose a significant public health risk. Traditional disinfection approaches, including thermal eradication and chemical oxidation, often fail to achieve stable, measurable microbial control. This study evaluates a mineral oxychloride-based method for continuous microbial reduction and biofilm suppression within hospital and extended care facility water systems. Data were collected by Legionella Specialties from over 105 facilities across the United States.

In accordance with the U.S. Environmental Protection Agency’s description of environmental testing, which includes analyzing the internal plumbing systems of buildings for the presence of Legionella pneumophila (the bacteria causing Legionnaires’ disease) and related water quality parameters such as pH (a measure of water acidity), temperature, and disinfectant residual (the remaining amount of disinfectant in the water) to assess treatment effectiveness and overall water quality (U.S. Environmental Protection Agency [EPA], 2016, p. 22), baseline analyses in this study included measuring water conductivity (which reflects the amount of dissolved salts), pH, oxidation-reduction potential (ORP, an indicator of a solution’s ability to break down contaminants using oxygen), free and total chlorine (levels of chlorine available for disinfection), adenosine triphosphate (ATP, a molecule found in all living cells used here as a marker for the presence of microorganisms), and temperature. Among 1,213 initial baseline sample points, approximately 40% exhibited ATP readings greater than 5 relative light units (RLUs, a scale indicating how much ATP—and therefore microbial activity—is present), with some exceeding 1,578 RLUs, indicating high microbial activity. Following application of the mineral oxychloride method and standard flushing protocols over a six-month period, fewer than 1% of post-treatment samples exceeded an ATP reading of 5 RLUs.

These results demonstrate that mineral oxychloride treatment effectively stabilizes key water quality parameters, creating a measurable, sustained oxidative environment. The approach aligns with EPA guidance, emphasizing ongoing monitoring of disinfectant residual levels, temperature, and water chemistry as indicators of treatment performance, thereby supporting proactive Legionella risk management and compliance with current healthcare water safety standards.

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