Legionella reduction after conversion to monochloramine for residual disinfection

Abstract

Previous studies have shown that monochloramine disinfection of municipal water supplies is associated with decreased risk of healthcare‐associated Legionnaires— disease. A twoyear, prospective environmental study was conducted to determine whether converting from chlorine to monochloramine for water disinfection would decrease Legionella colonization of hot water systems. Water and biofilm samples were collected from 53 buildings. Prevalence ratios comparing Legionella colonization before and after monochloramine disinfection were adjusted for water system characteristics. Legionella colonized 60% of the hot water systems before monochloramine conversion versus 4% after conversion. The median number of colonized sites per building declined significantly with monochloramine disinfection. Increased prevalence of Legionella colonization was associated with water heater temperatures below 50oC, buildings taller than 10 stories, and interruptions in water service. Although no outbreaks of Legionnaires— disease were found, the study provides support that use of monochloramine in water supplies may reduce Legionella transmission and incidence of Legionnaires— disease.

Degradation of Polymer & Elastomer Exposed to Chlorinated Water—A Review

“…As chloramination has become more widespread, several utilities that switched from free chlorine to monochloramine-based systems have reported prob-Open Journal of Organic Polymer Materials lems with substantially higher rates of elastomer failure within their distribution networks [149] [150] [151]. Reiber Steve (1993) [151] evaluated elastomer degradation involved an accelerated life cycle testing protocol whereby sets of tension mounted coupons were exposed to specific chlorine and ammonia concentration at elevated temperature.…”

Drinking water quality concerns from chloramine‐induced degradation of elastomeric compounds

“…For more than 50 years, elastomeric materials have been used ubiquitously in drinking water distribution systems in a variety of applications ranging from rubber gaskets, valves, hydrants, and fittings to a variety of piping materials, including flat gaskets in mechanical joint connections, molded or extruded pipe gaskets, O‐rings (mechanical joint gasket, push‐on joint gasket), flapper valves, diaphragms, valve seats, pump impellers, pond liners, check valves, and chemical feed pumps (AWWA Committee on Gasket Materials for Water Works Service, 1998). As chloramination has become more widespread, several utilities that switched from free chlorine to monochloramine‐based systems have reported problems with substantially higher rates of elastomer failure within their distribution networks (Weintraub et al, 2008; Seidel et al, 2005; Reiber, 1993; Simmons, 1988). As an example, when Austin, Texas, converted a portion of its drinking water distribution system to chloramine, the city received numerous complaints about black specks in the water within 12 months of the conversion (Kirmeyer et al, 2003).…”