Legionella

Definition

A waterborne bacterium that thrives in warm, stagnant, biofilm-rich systems and can cause serious respiratory disease in people.

Legionella prospers in warm water between 77 and 113 degrees Fahrenheit, intermittent flow, complex plumbing, and biofilms that provide shelter and nutrients, optimal around 95 to 105 degrees Fahrenheit. It is often associated with biofilms and free-living amoebae or protozoa that protect it from disinfectants and support amplification, and it spreads through aerosols from cooling towers, fountains, and showerheads. It crosses a line because it directly harms people, often immunocompromised people, making its control a public health responsibility and a systems problem rather than a chemistry problem.

Related concepts

ASHRAE 188 · Susceptible population · Aerosolization

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Part of The Blueprint of Water · 🦠 biology