Clean Cooling Towers One Key to Reducing Legionella Outbreakstest

August 2015

As the death toll and the number of people hospitalized with Legionnaires disease climb in New York City, heath officials have traced the source of the legionella outbreak to cooling towers from institutional and commercial buildings in the South Bronx.

The towers have been disinfected and are being monitored by health officials, according to a USA Today article. All affected buildings must submit long-term plans on how to prevent the return of bacteria to the cooling towers.

Ray Field, the director of Goodway Liquid Solutions, has worked on legionella control and chemical remediation technologies during his career, and he offers maintenance and engineering managers some tips on keeping cooling towers bacteria-free.

“The unfortunate outbreak of Legionnaire’s disease in New York City is enough to keep any facility manager awake at night,” Field says. “Your cooling tower is one of the most common sources for legionella bacteria. When algae and mold builds up in a dirty cooling tower, the tower’s warm water creates the perfect environment for bacterial growth.

“However, there are steps you can take to help reduce the chances of legionella growth. Ongoing and regular maintenance of the cooling tower is the most vital part of managing legionella outbreaks. What does this preventative maintenance involve?

• "Inspect towers monthly. Look for sediment, scale and slime, which can lead to buildup and help legionella grow and thrive.
• "Clean tower basin surfaces. Clean the basin when sediment is visible. Cooling-tower vacuums make it easier to remove contaminants without shutting down or draining the system.
• "Treat circulating water. Use a biodegradable descaler or antiscalant and dose biocides at recommended levels. Using a descaler in conjunction with biocides enhances biological control. A descaler will remove scale to allow biocides to tackle legionella in the tower more effectively.
• "Drain and clean. At least once a year, take the time to drain the system and perform a thorough cleaning before turning it back on. If the system has been offline for a long time, be sure to disinfect it.
• "Clean the fill. The tower fill is the perfect environment for bacterial growth, especially legionella. A cooling tower fill cleaner will remove lime scale and debris.

"In addition to preventing Legionnaires’ disease properly, caring for a cooling tower also can hold down energy and equipment costs. Putting together a maintenance plan and developing proper procedures is no longer optional. Managers need to take these steps now to minimize the risks of an outbreak occurring in a facility."