How to Comply with the City’s Cooling Tower Startup Regulations

Cooling tower owners have only a short window of time to coordinate startup efforts.



Springtime marks the time of year when HVAC cooling towers are put back into service. The NYC Department of Health and Mental Hygiene (DOH) recently issued seasonal startup tips for cooling towers to avoid unexpected delays and costs.

Cooling tower owners have only a short window of time to coordinate startup efforts.



Springtime marks the time of year when HVAC cooling towers are put back into service. The NYC Department of Health and Mental Hygiene (DOH) recently issued seasonal startup tips for cooling towers to avoid unexpected delays and costs.

The city’s regulations around cooling towers began in response to an outbreak of legionnaires’ disease in 2015. Legionnaires’ disease is a type of pneumonia that’s caused by the bacteria, Legionella, which grows in warm water. Symptoms resemble other types of pneumonia and can include fever, chills, muscle aches, and cough. Legionnaires’ disease can be caused by plumbing systems where conditions are favorable for Legionella growth, such as cooling towers, whirlpool spas, hot tubs, humidifiers, hot water tanks, and evaporative condensers of large air-conditioning systems.

In 2022, according to the DOH, 30 cases of legionnaires’ disease were identified within a community cluster in the Bronx. Twenty-eight people were hospitalized and two New Yorkers died. At the time, the DOH took samples of area cooling towers, and with molecular analysis of Legionella bacteria from human and cooling tower specimens, matched the Legionella strain found in a cooling tower with the strain found in two patients. The building owner was ordered to immediately disinfect the cooling tower and perform additional remediation.

Local Law 77 of 2015 was implemented to regulate cooling towers in the city. It requires the registration of all cooling towers, annual certification, quarterly inspection, and reporting of increased microbes to the DOH. The legislation also mandates the disinfection of cooling towers with levels of microbes that pose potential health risks. Violations of registry, certification, and inspection requirements are liable for civil penalties up to $10,000. And failure to disinfect towers with increased microbes is classified as a misdemeanor, punishable with fines up to $25,000.

As seasonal cooling towers come online, we’ll go over the compliance requirements for startup. Owners must not only make sure required tasks are completed but also are done within a certain time frame.

Coordinate Early with Water Management Team

Managing your building’s cooling tower requires a team of people who, together, can make sure that you’re following the city’s cooling tower regulations found in Chapter 8 in Title 24 of the Rules of the City of New York. Your cooling tower’s management and maintenance team includes all individuals who have a role in meeting legal requirements. Your water management team includes the following people.

Qualified person. You need an expert in water-quality management, planning, and operations. Such a person may be a New York State-licensed professional engineer, a certified industrial hygienist, a certified water technologist, or a certified environmental consultant with two years of experience in water-quality management. This person performs an annual review of the Maintenance Program and Plan (MPP) and updates the risk assessment. This person also evaluates startup procedures and creates an early plan of action.

Water treatment vendor. DOH suggests you schedule in advance for cleanings and disinfection, routine water treatments, visits, and summertime hyperhalogenation. The summertime hyperhalogenation is an additional preventive maintenance requirement aimed at reducing the risk of Legionella growth in cooling tower systems during the summer months, when Legionella and other bacteria can multiply very quickly.

Mechanical contractor. This person reviews mechanical conditions, performance of the cooling tower system, and conducts routine maintenance in preparation for startup or cleaning.

Building management. This person or group is responsible for the day-to-day oversight and management of a building, including its cooling tower system. They will keep facility personnel informed about cooling tower startup scheduling.

With a relatively short window of time for a coordinated effort by cooling tower owners and those responsible for each task, excellent communication and a comprehensive understanding of the rules and regulations are essential in a successful and compliant startup.

Cleaning and Disinfecting

Because each system is unique, cleaning and disinfection procedures must be tailored to your specific system and reflect the findings of your risk assessment. DOH says well-planned cleaning and disinfection at startup reduces risk and labor costs and saves energy.

The cooling tower startup requirements are described in §8-06(b) of Chapter 8 of Title 24 of the Rules of the City of New York. Tower systems must undergo a mechanical cleaning to remove biofilm, scale, or debris, followed by the application of a New York State-registered biocide. You should clean the cooling tower no later than 15 days before operation through power washing or scrubbing to remove biofilm, scale, or other debris.

Once cleaned, disinfect with an approved biocide to kill pathogens, such as Legionella. Cleaning and disinfection must follow industry guidance and procedures detailed by the qualified person in the maintenance program and plan (MPP). During disinfection, monitor pH and halogen residuals at two locations within the cooling tower system to verify that the target biocide residual is achieved. Be sure to fully drain the system of contaminants. Cleaning and disinfection dislodges material that will stay in your system unless all water is drained.

Conduct a Pre-Startup Inspection

The qualified person must conduct an inspection prior to the fan being turned on. The required inspection includes visually assessing the cooling tower system; inspecting all components for the presence of contaminants and other adverse conditions; checking that the water treatment equipment is working properly; and ensuring that records are complete.

Fill System and Circulate Water

Following the cleaning and disinfection, the tower system is filled with water and circulated with biocide as specified in the MPP. At this point, the system is in operation and must meet all NYC requirements.

DOH advises that you always maintain adequate circulation and treatment while in operation. Standing water, low flow, and improperly cleaned system components such as backup pumps, chillers, and cooling tower cells, that may not operate at all times or are under automated control. These components should be drained after use and cleaned and/or disinfected before placing them back into operation.

Take Legionella Sample

A Legionella bacteria sample must be taken prior to the fan being turned on, to validate the startup procedure. Within 14 days of startup operation, you need to collect and analyze a water sample for the presence of Legionella. The sample must be analyzed by a laboratory certified by the Environmental Laboratory Approval Program from the NYS Department of Health.

The results must then be interpreted, and action taken, as described in the cooling tower regulations. Any legionella culture result of 10 CFU/ml or above triggers immediate disinfection by increasing biocide concentration or using a different biocide within 24 hours.

Document Procedures

Be sure to keep detailed records of all procedures and actions performed in your operation records. Startup records should include cooling tower system ID; system startup date; individual cooling tower startup date, if different than the system startup date; and dates and procedures for startup cleaning and disinfection, including the service provider, pre-startup inspection, legionella sampling and test results, disinfection dose and circulation time, and water monitoring and treatment logs. Records of all startup activities should be available upon request and kept for at least three years.