I have been tasked with collecting water samples for a hospital with three campuses. Two of the campuses have large chiller systems with cooling towers. I am wondering what are the best samples to take to test for Legionella.
For hot and cold potable water, should I try to test the furthest point from the source, directly from a tap?
Sample one or two locations per floor and a minimum of ten outlets (sinks and showers) is recommended. Along with that, sample the hot water tanks and/or the hot water recirculating line (return line).
Follow-Up:
Do the ice machines need testing?
Reply:
As a healthcare facility with high risk occupants, we would say yes – test ice and water (if there is a dispenser) from ice machines. You may have to fill a couple of bottles with ice to provide enough water for testing.
Follow-Up:
Should I test the condensate drains from air handlers that distribute air throughout a building?
Reply:
Generally speaking, these pans should not accumulate water and are not a generator of significant aerosols. Pans are more often a source of odor problems due to mold growth rather than a source of transmission for Legionella. We do not recommend testing these.
Follow-Up:
Cooling towers are located outside and on the roofs. Are these potential sources of Legionella?
Reply:
Yes, cooling towers should be tested for Legionella when operating. There are outbreaks that have been linked to cooling towers. I’d recommend quarterly testing. For seasonally operated towers, test during the start up, during peak demand, and in the early fall when they may be used intermittently.