Since July 10, the citizens of New York City have been on alert following the discovery of an outbreak of Legionnaires' disease, a bacterial infection that spreads through water systems and can be deadly to smokers and the elderly. Already, ten people have died, 100 have tested positive for the disease, and officials think more people will be diagnosed before the outbreak is contained. For a detailed explanation of Legionnaires' disease, symptoms ands how it is spread, you can read VOX EXPLAINERS HERE.

This is one of the most frequently asked questions. While fluoride is beneficial at recommended levels, excessive exposure can lead to adverse effects. The key is maintaining appropriate fluoride levels, typically 0.7 milligrams per liter, as recommended by the U.S. Public Health Service. Many fringe theories and misconceptions about fluoride have circulated over the years, often causing unnecessary concern. However, extensive research and studies have consistently shown that fluoride, when used at the recommended levels, significantly improves dental health by reducing the incidence of cavities and tooth decay. The U.S. Public Health Service's recommendations are based on rigorous analysis and aim to balance the benefits of fluoride with the need to protect against any adverse effects.

These include thermal (super heat and flush), hyperchlorination, copper-silver ionization, ultraviolet light sterilization, ozonation, and instantaneous steam heating systems. Because some methods have not always proven completely successful or have not provided permanent protection from recolonization, a combination of these methods may be the most effective way of managing water systems and preventing future outbreaks.

Thermal disinfection, hyperchlorination and copper-silver ionization as well as the use of other biocides are something that we recommend you do or if you are doing these things, we recommend you continue. We believe that it is imperative to maintain a residual in the water supply for continuous killing capability. However, Ozonation and Ultraviolet Disinfection are viable options in the treatment to prevent Legionella.

A UV light sterilization system can be positioned to disinfect the incoming water, or it can be installed at a specific place in the pipe system that services a designated area. No chemical by-products are produced, and the taste and odor of water from a water distribution system containing a UV sterilizer are not affected. The UV sterilization system requires maintenance in order to prevent scale from coating the UV lamps. The system does not provide residual protection, so continuous disinfection is very important.

Ozone, which is generally created using an ozone generator, can be used to kill L. pneumophila. Ozone instantaneously inactivates Legionella; however, it has a short half-life and decomposes quickly back to oxygen. A second form of disinfection may be required in the distribution system for residual protection. Also, ozonation is more expensive than hyperchlorination, and a large amount of space is required for the air preparation equipment or oxygen tanks and contacting tank.

Conclusión

There is no question that Ultraviolet Disinfection and/or Ozone should be part of any cooling tower treatment regimen it just shouldn't be the only method. There needs to some kind of residual disinfectant and/or biocide to prevent re-contamination downstream.

US Water Systems Ultraviolet Disinfection Systems