Legionella Does Not Grow in Low-TOC Water

A test system supplied with different types of warm drinking water without disinfectant under controlled hydraulic conditions showed that treated aerobic groundwater (0.3 mg C per liter of organic carbon) induced a low biofilm concentration that supported no or very limited growth of L. pneumophila. Elevated biofilm concentrations and L. pneumophilacolony counts were observed on surfaces exposed to two types of extensively-treated groundwater containing 1.8 and 7.9 mg C per liter and complying with the microbial water quality criteria during distribution. Control measures in the warm tap water installations therefore are essential for preventing growth of L. pneumophila.

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http://aem.asm.org/content/early/2016/12/12/AEM.02737-16.abstract

Implication: Respirators, C-PAPs, humidifiers and other devices that use distilled water may be safe from Legionella.