Permits and Licenses Health Academy Food Operators Opportunities

Cooling Towers in NYC

Changes to Cooling Tower Regulations: Effective May 8, 2026

Notice of Adoption to Amend Chapter 8 of Title 24 of the Rules of the City of New York Concerning Cooling Towers (PDF, April 8) includes clarification that monthly Legionella sampling must be conducted at least every 31 days, among other changes.
Local Law 159 of 2025 requires that Legionella sampling be conducted monthly instead of every 90 days.
Compliance inspections should be conducted once every 90 days.

Cooling Towers and Legionnaires’ Disease

Cooling towers are part of large air conditioning or refrigeration systems, often located on building rooftops. Cooling towers cool indoor spaces by removing heat from indoor air using water and evaporating it as mist into the outdoor air.

The cooling tower system contains warm water. This creates an ideal environment for the rapid growth of Legionella bacteria, especially if the system is not maintained and regularly treated with biocide chemicals to control bacteria growth.

The mist released from cooling towers can carry these bacteria out into the environment. People may then breathe in the Legionella bacteria.

For some people, especially those with certain risk factors, breathing in Legionella bacteria can cause a type of pneumonia called Legionnaires’ disease.
Legionnaires’ disease is not transmitted from person to person.
Learn more about Legionnaires’ disease at Legionnaires' Disease

Cooling Tower Law and Requirements

In response to a large Legionnaires' disease cluster in the South Bronx in 2015, the New York City Council enacted a local law. Along with regulations from the NYC Health Department, this law requires building owners to register, maintain, and test the water in their cooling tower systems to reduce the risk of Legionella bacteria growth and prevent community clusters of Legionnaires’ disease.

In 2025, after a cluster of Legionnaires’ disease in the Central Harlem neighborhood, the New York City Council and NYC Health Department further strengthened the cooling tower law and regulations.

There are about 5,000 registered cooling tower systems in New York City. The NYC Health Department conducts routine inspections to promote compliance with the requirements. They also provide rapid environmental response in the event of a Legionnaire’s disease cluster investigation.

Note: Window unit air conditioners and other cooling systems that do not recirculate water and release mist are not cooling towers. These devices do not create a risk of Legionnaires’ disease and are not subject to these laws and regulations.

Learn more about the NYC cooling tower law and requirements for owners and operators at Cooling Towers: Information for Owners and Operators

Cooling Tower Inspections

The NYC Health Department regularly inspects cooling tower systems across the city. Each inspection includes a review of each system’s Maintenance Program and Plan and operational records. The Maintenance Program and Plan explains how the system is monitored, cleaned, and disinfected to help prevent Legionella bacteria from growing.

Building owners must keep records of all cooling tower water maintenance activities for at least three years. These records must include details regarding:

Routine monitoring
Routine maintenance
Compliance inspections
Steps taken for corrective actions
Water treatment activities
Water quality checks and measurements
Water test results (including for Legionella)
Cleaning and disinfection records

You can check cooling tower inspection results at Health Department Cooling Tower Inspection Results. Search by building address or building identification number (BIN).

Additional Resources

Learn more about the NYC cooling tower compliance requirements at Cooling Towers: Information for Owners and Operators
Cooling Tower Annual Certification (PDF)
Safe Cooling Tower Operation During Heat Waves (PDF)