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Old 08-01-2022, 07:39 PM   #32
XCR-700
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Quote:
Originally Posted by SailinAway View Post
Legionnaire's bacteria can grow in water heaters if the water isn't hot enough. This article explains how energy conservation efforts by the government---recommendations to lower water heater temperatures to 110 degrees---led to an increase in Legionnaire's disease: https://www.phcppros.com/articles/82...-water-systems

Quote from a report cited in that article: "A minimum storage temperature of 131 F is essential to prevent the spread of Legionnaires’ disease (131 F is the temperature at which Legionella begins to die). To assure a safety factor, the minimum storage temperature should be 135 F."

CDC: "Legionella grows best within a certain temperature range (77°F-113°F). To keep water outside the range for Legionella growth, it is important to keep cold water cold and keep hot water hot."

Empirical study: "L. pneumophila still persisted up to 58 °C [136F], with evidence that it was growing under the conditions of this study. Further, exposure to 51°C [124] water in a low-use tap appeared to optimally select for L. pneumophila (e.g., 125 times greater numbers than in high-use taps)."

So I was mistaken in my statement that 110 degrees is safe. Numerous websites cite that figure as safe, including some government energy conservation sites, without giving evidence.
So how does this work for tankless heaters? Can there be no growth if there is no tank?

Interesting this information is not more widely communicated. Begs the question why,,,
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