Legionella Controlled while ReducingChemicals


The water quality of a cooling tower system at a commercial facility in China continued to operate below standards for the first half year of 2008. Legionella bacteria was discovered in the system along with other microorganisms. Commercial chemicals such as biocide, scale and corrosion inhibitor were used in the closed loop condensing water.

Chemicals were changed frequently but failed to achieve a desired result. A 30 day trial of Hydropath technology was arranged, with baseline testing and sampling schedule developed. One Hydropath device was installed to the condensing water supply header pipe.  No chemicals were applied during the trial.


The clarity of condensing water became apparent in less than two weeks and the total bacterial count was reduced to below 1,000CFU/mil and Legionella was not detected. Despite the absence of chemical additives during the test period, the bacteria levels remained below targeted levels. Hydropath was permanently installed for long term operation.

Due to relationships with the chemicals supplier, the Hydropath device was discontinued for a 30 day trial of new chemicals. The total bacteria count and Legionella counts reached an unacceptable level in the water testing report of the following month and Hydropath was returned to service.