Legionella in cooling towers has been a problem for decades. Even though many companies and people have known this, many still simply ignore testing for it. But since the recent outbreak that has resulted in
10 deaths in New York City legionella monitoring and cleaning awareness is once again a hot topic. We have been asked a number of times what is the best cleaning procedure for legionella?
First, that has always been the big question. For decades, people have avoided checking for legionella, because they did not have a solution for cleaning it or killing it and they had no action plan if a legionella test was positive. So many people and companies have completely avoided testing for it because they had no solution. A few large corporations started a complete water hygiene division over a decade ago following in Europe's footsteps, which included implementing legionella testing in all cooling towers, but from what we can tell there was little market penetration at implementing for a complete hygiene water solution that included the cooling towers.
So how do you clean legionella? Instead of cleaning legionella we would prefer using the words "kill legionella" since legionella is a waterborne pathogen and it must be killed to effectively "clean" your system.
To the best of our knowledge, one solution for killing legionella is to try using a high concentration of hydrogen peroxide. Apply it directly to kill it. Also, you must use protective respiratory equipment when around legionella. Legionella may become an air borne pathogen which may severely sicken or kill you. Another legionella outbreak where hundreds of people were sicken was at the playboy mansion in 2011 where the Propylene Glycols levels in the fog machines were too low to prevent bacteria development and legionella was present in the fog machine solution. So again we stress the importance of using proper protection equipment when killing legionella. Use a legionella test kit to confirm the kill. If it did not kill off the legionella, you may consider using another biocide to attempt to kill it.
Prevention is the best solution
Hopefully you have successfully killed off your legionella. Now prevention is the best solution for another outbreak. The best chance to minimize the developing legionella is to use an oxidizer and alternating non oxidizer program biocide cooling tower program.
An example of oxidizer chemical is
Bromax. Great alternating biocides, Glutaraldehyde and Isothiazolin , should be used weekly an alternating the dosage to prevent the bacteria form becoming immune from these biocides. Again, make sure to use protective respiratory equipment.