Legionella Control in Cooling Towers

Cooling Tower

In my post of March 2, 2015, Using Soft Water for Cooling Tower Makeup, I discuss the benefits of operating cooling towers at high pH and up to 10 cycles of concentration. Among other benefits, this creates an environment that is outside the amplification range of common bacteria that inhabit open cooling water systems.

In the Summer 2016 issue of AWT’s journal, Analyst, Alex Ramimian-Pour of Michael Baker International and Eric Anderson of GE Water and Process Technologies discuss how using soft water makeup serves to control pathogenic organisms such as Legionella p.  They further argue for the benefits and reliability of bacteria monitoring using ATP technology. You can find their article at:

Legionella Outbreak Prevention for Cooling Towers

Using soft water for cooling tower makeup is a non-traditional approach. Most cooling towers are operated with hard water makeup. This requires that the cycles of concentration, pH, alkalinity and TDS are limited by excessive bleed to prevent scale deposition in heat exchangers and process equipment. (Most cooling towers operate at 4 cycles of concentration.)

Dan Duke of Water Conservation Technology International Inc. (WCTI) has advocated for the use of soft water makeup as part of a comprehensive cooling water treatment program for many years. His research and development has yielded unique technology for producing soft water for use as cooling tower makeup. This work has resulted in several patents. You can find more information at:

Water Conservation Technology International, Inc.

Overall, using soft water for cooling tower makeup offers many advantages over traditional hard water makeup. This includes enhanced scale control, corrosion inhibition, microbiological control and water conservation. The majority of cooling towers would benefit from implementing this technology.


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