Protection Against Legionella: Cooling Tower Requirements

A cooling tower is part of a recirculated water system incorporated into a building's cooling, industrial, refrigeration or energy production system. All owners of cooling towers in New York State are required to register their towers in the New York State Cooling Tower Registry, prepare and implement a Maintenance Program and Plan, test their towers for Legionella, clean and disinfect them, andp notify their local health department and the public when they identify elevated levels of Legionella in their cooling tower water. Cooling towers are tested for Legionella to assess the effectiveness of routine disinfection and maintenance.

Resources for cooling tower owners, operators, water treatment consultants and inspectors are provided below. Please refer to Title: Subpart 4.1 - Cooling Towers for a full listing of regulatory requirements.

Cooling Tower Registry

Register a cooling tower and submit reports

All owners of cooling towers in New York State are required to register their towers and maintain their records on the New York State Cooling Tower Registry (Subpart 4-1.3). Registries must be updated every 90 days while the tower is operational.

Cooling towers in New York City must also be registered with the City’s Registry.

Notification of Exceedance

Cooling tower owners must notify the local health department within 24 hours of receipt of a Legionella culture sample result that exceeds 1,000 colony forming units per milliliter (CFU/mL). Owners must also notify the public of test results in the manner determined by the local health department or the New York State Department of Health (Subpart 4-1.6 and Appendix 4-A).

Maintenance Program and Plan

Prior to the initial start-up of a newly installed cooling tower, the owner must obtain a Maintenance Program and Plan for each cooling tower. Each active cooling tower must have an updated Maintenance Program and Plan. (Subpart 4-1.4). This plan must be developed in accordance with ASHRAE Standard 188-2018 Legionellosis: Risk Management for Building Water Systems p. 7-8 (Available for viewing at Read-Only Versions of ASHRAE Standards under Current Popular Standards). You may use this template for the maintenance program and plan.

Legionella Culture Analysis

All Legionella culture analyses must be performed by a laboratory certified by the New York State Environmental Laboratory Approval Program (ELAP) (Subpart 4-1.5). Please contact or call (518) 485-5570 to find a certified laboratory.


Any person who disinfects a cooling tower must be a certified commercial pesticide applicator or pesticide technician who is qualified to apply biocide in a cooling tower. Only biocide products registered by the New York State Department of Environmental Conservation for use in cooling towers or pesticidal devices produced in a USEPA registered establishment may be used in disinfection (Subpart 4-1.7 and Appendix 4-A).

Variances and Waivers

An owner may submit a written application to a local health department for a variance for a period not exceeding 90 days from any provision. It must include an explanation of why the variance will not present a danger to public health (Subpart 4-1.11(a)).

The New York State Department of Health may issue a waiver for any provision of the regulation if staff are satisfied that the waiver would not present a danger to public health. Waivers may also be revoked upon determination that the waiver may present a danger to public health (Subpart 4-1.11(b)). To apply for a waiver, please email

Inspections and Certification

All cooling towers must be inspected prior to seasonal start-up and every 90 days while in use. Cooling towers also need to be inspected following maintenance (Subpart 4-1.8(a)).

All cooling towers must obtain a certification by November 1 of each year.  The certification should attest that the cooling tower has a maintenance program and plan, and that all activities within that plan or required by the regulation were implemented (Subpart 4-1.8b). You may use this template for the annual certification documentation.

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