All cooling tower systems must be sampled for the presence of heterotrophic bacteria once a week. They must also be sampled for the presence of Legionella at least once every 90 days.  

Water in a cooling tower system must be treated at least once per day while the system is in operation. Water treatments must include approved oxidizing chemicals and biocides in quantities sufficient to control the presence of Legionella, minimize biofilms, and prevent scaling and corrosion. Please see below for further guidance on water treatment. 

The State’s emergency rule requires you to report each date that you collect Legionella bacteria in your tower. For each date, you must report the results of your sampling and the date of any action taken to remediate the condition.  

The City’s emergency rule requires you to notify DOHMH within 24 hours about Legionella bacteria results only if you find more than 1,000 CFU/mL.  



4.3.1. Inspection

Performed by qualified persons, which are NYS licensed and registered professional engineers, certified industrial hygienists, certified water technologists with training and experience, or environmental consultants with operational experience in water management planning and operation. 

Test results must be filed within 5 days of the inspection date. When reporting test results, include any Legionella results and last HPC results by using the online reporting website for that agency.