How to Prevent Legionella Pneumophila with Water Additives

Chlorine has shown to be effective at controlling Legionella bacteria and is applied at higher dosages when Legionnaires’ disease has been detected or bacteria levels are found to be high.

One effective treatment strategy is the application of continuous chlorination or if the situation permits it, intermittent feed of chlorine to achieve a free chlorine residual. Sources of chlorine can be gaseous chlorine, but because of safety concerns and reporting requirements, a liquid sodium hypochlorite solution of 12.5% activity (12% as chlorine) is commonly used. Liquid sodium hypochlorite is commonly the most cost effective source for the chlorine.

Sticks of calcium hypochlorite 1” and 3” are also a simple, convenient, passive remedy; however, it adds calcium to the system water and increases scaling potential.

Cooling towers provide an ideal environment for the growth of Legionella pneumophila. Guidelines published by industry groups and governmental bodies recommend the use of oxidizing biocides for the control of L. pneumophila populations. The oxidizing biocide bromochlorodimethylhydantoin (BCDMH)[1] has been used for more than 25 years to control microbial populations and biofouling in industrial cooling water systems.

[1] BCDMH against L. pneumophila. BCDMH achieved >99.9% reduction in viability within 10 minutes of planktonic, pure culture L. pneumophila with 1 ppm free residual chlorine in a typical cooling water. Studies in dynamic laboratory systems inoculated with a natural microbial flora showed that BCDMH was equally effective against planktonic and sessile (biofilm) populations of L. pneumophila. Several excellent field efficacy studies have been conducted with BCDMH. These studies indicate that the continuous application of BCDMH to achieve 1-2 ppm free residual chlorine was effective at reducing viable L. pneumophila counts to undetectable levels in the recirculating water. Total bacteria counts were also reduced in all cases by the BCDMH treatment.

This convenient, proprietary (patent pending) ready-to-use product of chlorine dioxide in water (3,000 ppm) is especially effective against Legionella pneumophila and does not require an on-site generator.

• Kills bacteria, viruses, and waterborne pathogenic parasites at relatively low dosages and contact time.
• Does not produce unwanted chlorinated organic by-products like THMs or HAAs.
• It works synergistically with chlorine that is already present in municipal water.
• As a dissolved gas, it rapidly fully penetrates and destroys bio-film that is resistant to chlorine and many other disinfectants; this bio-film is a primary source of Legionella contamination in hospitals and other institutions.
• Packaged in 5 gallon pails, 15/30 & 55 gallon drums and 330 gallon IBCs.
• Special pumps, piping, fittings, and tubing are required, as well as storage between 32°F and 14°F.
• Best if used within 90 days.