While not always fatal, a condition known as Legionnaire’s Disease has taken lives in the past and can, at the very least, make people very ill.
The waterborne Legionella pathogen that causes typically treatable but potentially fatal Legionnaire’s disease is found in domestic drinking water systems, cooling towers, evaporative condensers and decorative fountains. Other contained systems like vehicle washing equipment are also at risk. A May 2008 public Legionnaires’ outbreak was linked to a self-serve carwash in Australia and two Albany, NY bus washing system employees who contracted the illness in August 2007, according to industry trade reports. ( source )
Health officials and scientists often find Legionella pathogens in closed water systems with elevated water temperatures. The higher temperatures make maintaining an adequate disinfectant level in the water very difficult and for that reason certain pathogens can flourish in these environments.
In cases where the water gets converted to a mist by sprinkler systems, produce misters or other devices, the Legionella pathogen can become airborne and have an excellent opportunity to infect a large number of people very rapidly.
Signs of exposure include, but may not be limited to, high fever temperatures and flu-like symptoms. People with suppressed or weakend immune systems tend to become infected faster and often times more seriously than people with healthy immune systems.
What methods exist for preventing the growth and distribution of the Legionella pathogen?
Thermal Heat/Flush – Water temperature raised to as high as 160ºF for up to 30 minutes to sterilize systems. Chemical-free, commonly-used method requires no additional equipment. Labor intensive and can prove ineffective for long-term Legionella infestation management. Can damage older pipes and creates potential for scalding.
Shock (Hyper) Chlorination – Chlorine injected into water distribution system. Initial shock chlorination levels approach 50 ppm, and taper off to create 2ppm to 5ppm chlorine cycle. Chlorine decomposes rapidly at elevated water temperatures; Legionella re-colonization can occur in as little as one to two weeks during continuous chlorination following the shock. Highly corrosive to plumbing (can be offset in part with silicate corrosion control). Places facility employees handle stored chemicals or implement disinfection at risk for exposure to chlorine byproduct Trihalomethane (THMs, linked to several types of cancer).
Chlorine Dioxide – Chlorine Dioxide (CIO2) is EPA-approved for potable water disinfectant use under CFR Par 141-National Primary Drinking Water Regulation. Commonly used in Europe, CIO2 is a gas generated by either chemical or electrolytic means and distributed throughout the water distribution system. The powerful oxidant kills Legionella and other bacteria. CIO2 readily decomposes in drinking water and residuals decrease as water system temperatures rise, making this treatment approach difficult in hot water systems. CIO2 is corrosive to plumbing infrastructure and creates byproducts including chlorate and chlorite; field testing for EPA maximum limits is required.
Copper-Silver Ionization – Latest advance in disinfection methods dissolves and distributes small amounts of copper and silver ions throughout water systems to eradicate bacteria. Continuous eradication metallic ion unit is required. Highly effective in eliminating Legionella, particularly in recirculation hot water systems, according to research and monitoring of hospital-implemented systems by Janet F. Stout, Ph.D., University of Pittsburgh special pathogens laboratory director and an international expert on waterborne pathogens. ( source )
Each Legionella prevention method requires testing on one level or another. Thermometers, high range free chlorine test strips, chlorine dioxide test strips, and/or dissolved copper in water test strips can all play a key part in maintaining a safe, Legionella-free closed water system.