Conventional water treatment practice advocates the use of a combination of oxidizing and/or non-oxidizing biocides for the control of bacteria populations in cooling tower operation including Legionella p.
In a peer-reviewed article, Natural Pathogen Control Chemistry to Replace Toxic Treatment of Microbes and Biofilm in Cooling Towers by Lon Brouse, et al, published on March 31, 2017 in Pathogen Journal, the authors present a convincing argument for using soft water makeup to create a high pH and total dissolved solids (TDS) environment in the cooling tower. The natural antimicrobial benefits of this approach include water conservation and reduced toxic impact on the environment.
It has been my experience and practice to advocate the use of soft water makeup for cooling tower operation to achieve improved efficiency including water conservation, scale control, corrosion mitigation and microbiological inhibition. Others, such as Water Conservation Technology, Inc, have developed a technology source that practices such environmental inhibitory chemistry. This treatment approach is gaining momentum as cooling tower owner/operators seek ways to conserve water, reduce cost and enhance the natural environment.
You may reference the Pathogen Journal article at:
You may also wish to review my blog post on the benefits of using soft water makeup in cooling tower operation: