Summary: Legionella in hotel hot water systems remains a potential risk for hotel owners and designers. This article summarizes the status of the progress toward dealing with Legionella in hotels.
Janet Stout, PHD and her colleague Dr. Victor Yu, MD are leading the research in Legionella in buildings in general. In my efforts to find the best solution to this problem in hotels, I have begun conversations with Dr. Stout to see what we as designers can do to make sure our buildings are not at risk for a Legionella incident. Here is some of what I have learned so far. Please note that this subject is still under study and there are few conclusive statements that can be presented at this time. I will be following this article with updates as my investigation progresses. Anyone is welcome to call and discuss.
Matthew R. Freije is another expert I have discovered from his article “10 Ways Plumbing Engineers Can Prevent Legionnaires’ Disease” in the March 2009 issue of PME magazine. He is teaching a seminar on “Performing High Quality Legionella Assessments” in May 19-21, 2009. I will be attending to learn more and will share what I learn.
What we know about Legionella:
- Legionella is prevalent to some degree in almost all hot water systems.
- Most people have adequate immunity to low levels of Legionella bacteria, otherwise it would be a more serious problem.
- Immune compromised people are at higher risk to Legionella in situations that would not otherwise be a concern for the average person.
- Our practice of keeping hot water at 120 degrees creates a breeding ground for Legionella.
- Raising the temperature of hot water to above 140 degrees is helpful, but not the full answer. Legionella is not fully killed at higher temperatures and no hot water system has a homogeneous temperature throughout. For example, the bottom of a hot water storage tank may seldom reach the average tank temperature, especially near the cold water inlet.
- There are recognized methods of reducing the presence of Legionella, but none are 100 percent effective. The common methods include:
- Thermal Eradication: Boil the suckers!
- Superchlorination: Kill them with chlorine like in a swimming pool.
- Copper-silver ionization: Copper ions break down the skin of the Legionella, and the silver ions mess up the DNA. (or something sinister like that)
- Filtration with 0.2 micron filters. At least the critters are fat enough to capture.
Testing for Legionella is the first step to knowing if your hotel has a problem. The testing costs about $150 per sample, and it is recommended that a typical hotel be tested at about 5 places.
See Legionella Sample Collection for how to do this at your hotel.
ASHRAE is funding research into the issue of Legionella in cooling towers. This is another breeding ground for Legionella that concerns many full service hotels.
Since I am just beginning to understand the subtleties of this topic, I will conclude this article for fear of continuing on and spreading untrue information. However, it is my intention to continue learning about this subject and sharing what I learn along the way.
Update April 3, 2009: Here is a link to the best article I have found so far encompassing the full range of Legionella issues: Legionella 2003 by the Association of Water Technologies.