AWWA JAW66307

AWWA JAW66307 Journal AWWA - Legionella Reduction after Conversion to Monochloramine for Residual Disinfection
Journal Article by American Water Works Association, 04/01/2008

Weintraub, June M.; Flannery, Brendan; Vugia, Duc J.; Gelling, Lisa B.; Salerno, James J.; Stevens, Valerie A.; Rose, Charles E.; Besser, Richard E.; Fields, Barry S.; Moore, Matthew R.; Conroy, Michael J.

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Legionnaires' disease is a type of pneumonia caused byfreshwater bacteria of the genus Legionella. Previousstudies have shown that monochloramine disinfection ofmunicipal water supplies is associated with decreased riskof Legionnaires' disease transmitted in healthcare settings.The authors performed a two-year, prospective environmentalstudy to determine whether converting fromchlorine to monochloramine for water disinfectionwould decrease Legionella colonization of hot watersystems. Results of the study showed a significant reduction.Legionella colonized 60% of the hot water systemsbefore monochloramine conversion versus 4% afterconversion. These findings suggest that monochloraminein drinking water provides better control of Legionellagrowth in building plumbing systems than does chlorine.Although control of Legionnaires' disease is unlikely tobe a major factor in a water utility's decision to convertto monochloramine for residual disinfection, if watersuppliers convert to monochloramine to reduce concentrationsof disinfection byproducts, control of thegrowth of Legionella in potable water systems may be anadditional health benefit. Includes 37 references, tables, figure.