Hi Goskel In the UK, the ...

Hi Goskel

In the UK, the risk from Legionella  in cooling towers and elsewhere is controlled by good management practice. Guidance is available, principally, through the Health and Safety Executive.

http://www.hse.gov.uk/safetybulletins/coolingtowers.htm

It is the responsibility of an operator to develop a plan that identifies the risk and puts in place appropriate control measures. It is important that the measures are effectively and continuously monitored and corrective action taken, where necessary, to prevent a deterioration in water quality. 

Kind regards

Robert