City of Milwaukee Health Department

Legionella Q&A Panel continued...

The following questions were submitted during the Q&A Panel, but time ran out before they could be read aloud.

What about the use of one-time through cooling as opposed to the use of biocides (for system maintenance)?

Systems using once-through cooling water typically do not need to be worried about bacteria if the source is city water.  Corrosion is more of an issue.  Once-through systems do not typically aerosolize the water like a cooling tower does.  Bacteria slimes might form that inhibit heat transfer where the use of a biocide might be desired. This would be done more to control biofilm than to prevent Legionella. - Joe Russell

How long has Milwaukee Water Works added Monochloramine to the city (water)?

Please refer to the Milwaukee Water Works website for FAQs about Milwaukee's water quality and contact information.

(What is your) opinion on 2-day legionella test(ing)?

Not sure what is meant by two day Legionella testing. The Gold standard for Legionella testing is the culture.  The sample must be taken and sent so that the lab receives it in 48 hours.  This means it most likely will need to be sent overnight mail and cannot be sent on a Friday as most labs are closed on Saturday. Once the sample is cultured, the tests typically take 10 days for full incubation but problems can be detected in 7 days if the culture has high Legionella counts. Other types of testing is available but I would personally only use the culture test alone. - Joe Russell

Was (the) increase in Legionella in (the) north central associated with increases with any other water or airborne disease or monitored contaminants?

There was no known increase of other water or airborne contaminants. - Thomas Haupt

What are water utilities and water facilities, (and) healthcare (facilities) with cooling towers doing for routine monitoring? How often should a formal (legionella) test be performed?

Water utilities and facilities do not monitor for Legionella.  Typically the levels are very low and they are not required by the EPA to test for it.  There is no standard in healthcare yet.  This will change with the new standard coming out - ASHRAE 188P.  In my opinion, what a healthcare facility should be doing is at least twice during the first season of testing the cooling towers should be tested.  If the results are positive, then annual testing is recommended along with the implementation of a water management plan specifically for the control of waterborne pathogens.  For the domestic water, annual sampling should be conducted at a minimum of 10 distal sites to determine the percent positivity.  If the building is greater than 30% colonized, then a disinfection system should be installed and the system tested monthly until the % positivity drops below 30%.  Annual testing should be conducted after this. - Joe Russell

Was the reason only 11 cultures were sent in because of possible litigation if one of the cultures was the source? Or was the cultures test sent out with a disclaimer about if a test was positive there would be no litigation?

The number of environmental samples collected and submitted for testing was based on several variables, including epidemiological data, access to sites, and water system types. There was no plan to pursue litigation for positive tests. The samples were tested for data collection and surveillance purposes in an effort to understand the prevalence of the bacteria, bring awareness to the issue, and prompt the maintenance of any possible contaminated systems. - Kyle McFatridge

(Are there any) TAT (turnaround time) issues (with lab testing)? (What is the) availability of certified labs?

Samples should be sent to the lab within 48 hours to be cultured.  Results should be reported within 10 – 14 days.  A list of CDC Elite labs can be found here.   I personally use Dr. Stouts labs at the Special Pathogens Lab due to her expertise on the subject of Legionella and what that brings to Watertech of America, Inc. and our customers. - Joe Russell


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