Summertime Hyperhalogenation of Cooling Tower Systems (Amendment to Chapter 8 in Title 24 of the RCNY)

Adopted Rules: Closed to Comments

Effective Date: 
Tuesday, July 7, 2020
Download Copy of Adopted Rule (.pdf): 

Statement of Basis and Purpose

Statutory Authority

This amendment is made pursuant to sections 556 and 1043 of the Charter and section 17-194.1 of the New York City Administrative Code (Administrative Code). Section 556 of the Charter authorizes the Department to regulate all matters pertaining to the health of the City. Charter section 1043 grants the Department rulemaking authority. Section 17-194.1 of the Administrative Code requires owners of buildings with cooling towers to maintain, clean and disinfect such cooling towers and authorizes the Department to adopt rules to implement these requirements.

Chapter 8 of Title 24 of the RCNY (Chapter 8) contains the Department’s rules for the operation and maintenance of cooling towers in the City. A cooling tower is a device that extracts heat to the atmosphere through the cooling of a water stream to a lower temperature. The term “cooling tower” includes any evaporative cooling equipment with recirculating water, including direct (open circuit) and indirect (closed circuit) cooling towers, evaporative condensers, or evaporative spray fluid coolers capable of aerosolizing water. Common applications of cooling towers are for air conditioning, refrigeration, industrial/manufacturing processing or electric power generation. This includes mobile or portable cooling towers. A cooling tower may comprise one or more cooling tower cells.

Because water within a cooling tower uses heat exchange, it can provide an ideal environment for Legionella bacteria to grow, particularly if the cooling tower is not properly disinfected and maintained. Exposure to the Legionella bacteria (Legionella pneumophila) can cause Legionellosis disease. Cases of Legionellosis must be reported to the Department in accordance with section 11.03 of the Health Code and section 2.1 of the New York State Sanitary Code (found in title 10 of the New York Codes, Rules and Regulations). The more serious form of Legionellosis is a pneumonia known as Legionnaires’ disease; a less serious form of Legionellosis is known as Pontiac fever, which is a flu-like illness. Legionnaires’ disease is known to have a case fatality rate of 5-30%. The US Centers for Disease Control and Prevention estimates that there are between 8,000 and 18,000 cases of Legionnaires’ disease in the United States annually and that more than 10% of cases are fatal.1

Section 8-04 of Chapter 8 provides requirements for cooling tower process control measures. The Department is requiring a summertime hyperhalogenation, a one-time per year dosing of higher-than- normal levels of chlorine or bromine based biocide, to each cooling tower system between July and August 31. Periodic hyperhalogenation is an effective method of limiting Legionella in recirculating water by preventing the risk of biofilm growth, which can be a host for Legionella survival and replication. Periodic hyperhalogenation performed routinely, while ensuring water flow throughout the cooling tower system and all its components, may reduce the need for more intensive cleaning and disinfection procedures in the future. The Department’s Legionella sampling results indicate that concentrations of the bacteria are highest during the summertime months. Surveillance data also indicates more cases of Legionnaires’ disease during the summertime.


Accordingly, Section 8-04 is amended by establishing a new subdivision (f) requiring a summertime hyperhalogenation to be conducted for each cooling tower system at least once each year between July 1 and August 31. Summertime hyperhalogenation is expected to occur this summer, 2020, but an owner is not required to update their cooling tower maintenance plans until the 2021 cooling season. Finally, the penalty schedule in §8-09 of Chapter 8 is amended to include monetary penalties associated with the violation of this requirement.



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