Legionella Bacteria and "Cook & Flush" Procedures to Control it.

As many of you know, American Towers has had, for many years, an infection of Legionella bacteria in our domestic hot water system. From all indications we received this from our city water supply and it is a fairly common in large scale high rise facilities. From the beginning, we have followed the recommendations of the County Health Dept. with regular testing and periodic “cook and flush” procedures in an effort to keep our bacteria under control and well below the recommended OSHA threshold. Our efforts have been successful for the past several years. Our most recent Health Dept. water tests show elevated bacteria levels well above the OSHA threshold which prompts us to conduct another “cook and flush” procedure immediately. In this procedure, we elevate our hot water temperature to 150 degrees from our normal 135 degrees. Our past procedures have been very successful in reducing the bacteria to negligible levels which have persisted until now.

This “cook and flush” procedure elevates our water temperature to levels (150º F) that kills the bacteria in a matter of minutes. Our normal temperatures of 135º F kills the bacteria after 10 to 30 minutes but the source of our recurring infection lies with the fact that there are many areas of our hot water system (dead end or unused pipes or vacant condos) which do not circulate and apparently cool to temperatures in which the bacteria thrives and multiplies thereby re-infecting the entire system over time. During the cook and flush procedure, we elevate the water temperature to a level at which the water quickly kills the bacteria, but it is in the flushing procedure where we try to kill the bacteria in dormant pipes, faucets and showers, that rarely or infrequently get used where the bacteria may be growing and re-infecting other areas of the system. In this regard, it is very important for all owners and residents to run hot water for five to ten minutes in all outlets, showers, vanities and sinks in an effort to disinfect as much of our piping as possible. Our staff will also make efforts to address condos that are vacant or presently unoccupied. Our previous experience is tells us that 100% is not necessary to achieve excellent results but that more is still better to achieve longer lasting effects. When we began, we anticipated a cook and flush procedure every year to 18 months and it now appears that the Health Department's prognosis and predictions were accurate. We will continue to test periodically and perform cook and flush procedures as test results require.


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