Cooling Towers: Information for Owners and Operators

For detailed, step-by-step instructions on registration and uploading requirements, log into the NYC Cooling Tower Registration Portal and click the “Help FAQ” tab.

NYC Cooling Tower Portal Registration

Building owners and property managers must register all cooling towers, fluid coolers, and evaporative condensers through the NYC Cooling Tower Registration Portal. Each registration must include, at a minimum:

• A Building Owner contact
• A Building Permission Owner
• A Cooling Tower System Permission Owner
• A Qualified Person

You must actively monitor all contact emails and be available to receive and respond to important communications.

All cooling towers located in NYC must also be registered with New York State. For more information see: NY State Cooling Towers.

Portal Upload and Update Requirements

After registration, System Permission Owners and Qualified Persons must upload certain documents and updated information to the NYC Cooling Tower Registration Portal. See the following list for details.

• System Startup Date
• Where: Cooling Tower System Information page
• Who: System Permission Owner/Building representatives
• When: Within 5 days of putting system into operation for the season


• System Shutdown Date
• Where: Cooling Tower System Information page
• Who: System Permission Owner/Building representatives
• When: Within 5 days of system shutdown for the season


• System Operation Period
• Where: Cooling Tower System Information page
• Who: System Permission Owner/Building representatives
• When: At initial registration and whenever it changes


• Legionella Sampling Date Reporting
• Where: Qualified Person’s view
• Who: Qualified Person
• When: Within 5 days of water sample collection


• High Legionella Results (greater than 1,000 CFU/mL)
• Where: Cooling Tower System Information page or email CTCompliance@health.nyc.gov
• Who: System Permission Owner/Building representatives
• When: Within 24 hours of receiving results from the laboratory


• Summertime Hyperhalogenation Form
• Where: Cooling Tower System Information page
• Who: System Permission Owner
• When: Annually between July 1 and August 31 – submit within 30 days of completion


• Annual Certification or Statement of Non-operation
• Where: Cooling Tower Equipment Information page
• Who: System Permission Owner
• When: Annually by November 1


• Decommissioning Form*
• Where: Cooling Tower Equipment Information page
• Who: System Permission Owner
• When: Within 30 days of permanently removing the equipment from service

*If the equipment is undergoing an extended shutdown but may be reactivated in the future, email CTCompliance@health.nyc.gov for guidance on procedures and documentation.

Other records, such as the MPP and routine operational documentation, do not need to be uploaded but must be kept on site as part of the building’s records and made available to the Health Department upon request.

Cooling tower management requires a team of trained professionals and staff, each with specific roles and qualifications to ensure safe and compliant system operation.

Qualified Person and MPP Preparer

A Qualified Person is someone with expertise in water-quality management, planning and operations. They 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.

Qualified Person’s Responsibilities can include:

1. Develop, implement, update and provide annual certification of the MPP
2. Conduct routine Compliance Inspections at least once every 90 days
3. Verify that Legionella culture testing is performed at least once every 31 days
4. Upload Legionella culture test sample dates in the Portal within 5 days of sample collection
5. Supervise startup and shutdown procedures

Before hiring a qualified person, consider their experience with environmental science, cooling tower systems, licenses and permits, customer references, and any other relevant qualifications.

Responsible Person(s)

A Responsible Person works under the guidance of the Qualified Person to provide day-to-day oversight of the cooling tower system. They may be onsite building staff such as facility staff, engineers, superintendents, managers, porters or building custodian, or anyone regularly present at the building who assists with routine monitoring tasks.

Refer to Operational Records Requirements below for a full list of cooling tower tasks and how often they must be completed.

Water Treatment Consultant (for Chemical Treatment and Disinfection)

The chemical treatment provider must check compatibility between the cooling tower materials and added chemicals and biocides. They must evaluate and adjust treatment to minimize microbial growth, biofilm formation, corrosion, scaling within the water loop. Anyone applying biocides to cooling towers must have a Commercial Pesticide Applicator Certification in Category 7G - Cooling Towers, issued by the NYS Department of Environmental Conservation.

Laboratory for Legionella Analysis

All Legionella culture samples must be analyzed by a laboratory certified by the Environmental Laboratory Approval Program (ELAP) of the New York State Department of Health.

Cooling Tower Startup Procedures

When starting up cooling towers or additional components of a system for the cooling season or after a shutdown period, you must follow these startup requirements.

Startup procedures must be performed on a cooling tower system whenever it has been shut down or left untreated for 5 or more days. The Health Department recommends that water be continuously recirculated with treatment whenever the cooling tower is in operation.

If an individual system component, such as an additional chiller or tower cell, is brought online after the rest of the system, perform and document actions to address the potential risk of bacteriological growth in stagnant auxiliary components. For example, adjust treatment program or clean and disinfect prior to bringing additional components online.

Clean and disinfect the cooling tower

• Clean and disinfect the cooling tower system within 15 days before putting the system under heat load.
• Follow industry/ASHRAE guidance and procedures described in the MPP.
• Monitor pH and halogen residuals at two locations within the cooling tower system to verify that the target biocide residual is achieved.

Conduct a pre-startup inspection

• Enlist your qualified person to conduct and document the pre-startup inspection
• Visually assess the cooling tower system
• Inspect all components for the presence of contaminants and other adverse conditions
• Check that the water treatment equipment is working properly
• Ensure that records are complete

Fill system and circulate water

• Once disinfected, fill the cooling tower system with water and begin circulating biocides and chemicals, as specified in the MPP. At this point, the system is in operation and must meet all NYC requirements for water quality monitoring, biocide treatment, and bacteriological testing.

Take a Legionella culture sample

• Collect and analyze a water sample for the presence of Legionella within 3-14 days of startup.
• The sample must be analyzed by a laboratory certified by the Environmental Laboratory Approval Program (ELAP) from the NYS Department of Health.
• Interpret results and take actions as described in Table 8-1 of Chapter 8.

Document procedures

• Keep detailed records of all procedures and actions performed in your operation records. Startup records should include:
• Cooling tower system ID
• System startup date and/or individual cooling tower component startup date (if different than the main system startup date)
• 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, water monitoring and treatment logs.

Report system startup date in the Cooling Towers Portal within 5 days of putting system into operation for the season.

Water in a cooling tower system must be treated daily with oxidizing biocides and chemicals in quantities and at frequencies sufficient to control Legionella growth, minimize biofilms, and prevent scaling and corrosion. The person applying the biocides must have a Commercial Pesticide Applicator Certification in Category 7G - Cooling Towers, issued by the NYS Department of Environmental Conservation (NYSDEC). Water treatment must include an oxidizing biocide that is registered with the NYSDEC. The water treatment schedule must be included in the MPP.

Water must be treated using automated feed methods. Manual feed is only allowed if it is demonstrated to be effective at Legionella control. The manual application process must be specified in the MPP. Water must be continuously recirculated for the duration of chemical and biocide feeds, and for one hour after or longer.

Recordkeeping

You must keep records for all chemicals and biocides added, including the purpose of their use, manufacturer’s name, brand name, date and time of each addition, amount added, and the safety data sheet for each product as required by Chapter 8. These records must be made available to the Health Department upon request at the time of inspection.

The cooling tower system must be cleaned at least twice per calendar year and disinfected regularly to control the growth of bacteria, especially Legionella. Additional cleaning and disinfection is required when monitoring or water sampling results show elevated levels of Legionella that trigger corrective actions. Cooling tower systems that operate seasonally must be cleaned before startup.

Cleaning

Cleaning may involve disassembling system components and using physical or mechanical methods to remove:

• Biofilm
• Scale
• Debris
• Rust and other corrosion products
• Sludge
• Algae
• Any other potential sources of contamination

Disinfection

Disinfection involves applying one or more biocides at a specified concentration, under controlled conditions and for a set time period to kill or inactivate microorganisms that may pose health risks. As with routine water treatment, cooling tower disinfection must be performed by a certified pesticide applicator with a Commercial Pesticide Applicator Certification in Category 7G - Cooling Towers.

Summertime Hyperhalogenation

Between July 1 and August 31, all operating cooling towers must be disinfected by a summertime hyperhalogenation. This is a one-time, high-level biocide treatment to help prevent Legionella bacteria growth during peak risk months. The hyperhalogenation must be followed by a Legionella test 3 to 31 days after completing the disinfection.

• The System Permission Owner must submit a Summertime Hyperhalogenation Declaration Form through the Portal’s System Page within 30 days of completion.

Water Quality Monitoring

Water in cooling tower systems must be regularly tested for key parameters, including pH, conductivity, temperature, and disinfectant (such as chlorine or bromine) residual. Regular monitoring helps ensure that the system is operating safely and effectively.

Legionella bacteria sampling

Sampling and Record Requirements

• Legionella bacteria culture testing must be done within 3 to 14 days of cooling tower startup and at least once every 31 days while the cooling tower is operating.
• Legionella culture samples can be collected by the Qualified Person or anyone under the guidance of a Qualified Person.
• Samples must be analyzed by a laboratory certified by the Environmental Laboratory Approval Program (ELAP) of the New York State Department of Health.
• Any Legionella bacteria culture test result that is positive at a level of 10 CFU/mL or above requires corrective actions that operators must document. Required corrective actions depend on the level of positivity, and may include water treatment changes, disinfection, system cleaning and notification of the Health Department. Records must include the actions taken (with dates and times) and outcomes. Refer to Table 8-1 in Chapter 8 for specific requirements.

Sample Date Reporting

• A Qualified Person must report the sample collection dates within 5 days of collection, in the Portal (Qualified Person view).
• The cooling tower Building Permission Owner or System Permission Owner must invite a Qualified Person to create an account in the Portal. The email address must belong to an individual—not a company—and must be actively monitored and available for receiving and responding to communications.

Sample Result Reporting

• Legionella results of 1,000 CFU/mL or greater must be reported to the Health Department within 24 hours. Results can be uploaded in the Portal or emailed to CTCompliance@health.nyc.gov.
• The Health Department will follow up with the building owner, maintenance staff and water treatment professionals to make sure that the cooling tower system is properly cleaned, disinfected, and resampled.
• Routine Legionella results that are less than 1,000 CFU/mL do not need to be reported to the Health Department, but all required actions must be taken and documented.

Bacteriological sampling

• Test water at least once a week for heterotrophic bacteria.
• Dip slides are commonly used for this purpose and must be used according to New York State guidelines for heterotrophic bacteria testing. A dip slide test kit typically includes a small flexible plastic slide, sometimes also called a paddle, and has its own sterile container.
• To conduct the test, slide the paddle into the water and incubate it at the temperature and for the length of time required by the specific kit. Be sure to document the start and end times of the incubation in your records. Any bacteria present will grow into visible colonies. To interpret the results, compare the numbers of colonies on the dip slide to a reference chart to get the concentration of bacteria.
• The laboratory test for heterotrophic plate count (HPC) can be performed on a water sample instead of using dip slides. The laboratory analyzing the sample must be accredited by New York State ELAP program.
• Once you have a concentration of bacteria, compare it to action levels defined in the cooling tower regulations in Table 8-2 and take actions, if needed.
• Results should be recorded and reviewed as part of routine monitoring. Document all corrective actions in your operational records.

Sampling locations and times

It is important to choose water sampling and testing locations and times that represent the overall or typical quality of the water circulating in the cooling tower system.

• Sampling locations and times should be chosen by considering factors such as biocide timing, system complexity (water volume, number of cells), and water flow differences.
• The sample must be taken at least one hour after biocide or chemical treatment injection has finished.
• The water sampling locations must be listed in the building’s MPP.

Summary of Cooling Tower Requirements

The responsibility for performing each cooling tower operational requirement varies. Some facilities may hire a water treatment professional, or a Qualified Person, to handle a task. Others may have the job performed by in-house staff, or a Responsible Person. Requirements and minimum frequency are described as follows:

• Routine System Monitoring (visual assessment)
• Minimum Frequency: once per week
• Routine System Maintenance
• Minimum Frequency: follow manufacturer recommendations and industry best practices
• Cleaning
• Minimum Frequency: at least twice per year including system startup, and when conditions require (including corrective actions)
• Disinfection by Certified Pesticide Applicator (7G license)
• Minimum Frequency: at system startup, summertime hyperhalogenation (July 1 to August 31), and when conditions require (including corrective actions)
• Water Quality Monitoring (pH, temperature, conductivity, biocide residual from representative locations and times)
• Minimum Frequency: three times per week, with no more than two consecutive days between measurements
• Bacteriological Indicator Testing (from representative locations and times)
• Minimum Frequency: once per week
• Legionella Testing (from representative locations and times)
• Minimum Frequency: at system startup, every 31 days while in operation, 3 to 31 days after summertime hyperhalogenation, and when corrective actions are required
• Compliance Inspection
• Minimum Frequency: every 90 days by Qualified Person

Shutdown Is Full Drainage of Cooling Tower System

Full cooling tower system shutdown is when all water in all components of the cooling tower system is completely drained. However, there are modes of operation when only some components of the system are online and under heat load. This condition is considered partial operation. Improper shutdown or periods of partial operation may be associated with Legionnaires’ disease clusters. When a system is shut down for the season, you must report the shutdown date within 5 days.

Managing Partial Operations to Control Risk of Legionella Growth

Partial operation is allowed if risk mitigation strategies have been implemented and are described in the MPP.

Update your MPP to coordinate water treatment and mechanical maintenance, such as with an automated valve schedule.

• Address impacts of partial operation modes in the risk assessment and management, water treatment, and procedures sections of your MPP.
• Understand the operating modes including when and how a switch (valve schedule) occurs when components cycle between head load and standby. Use bypass piping if available to keep water circulating.
• Develop procedures for shifting between modes of partial operation. For example, include treatment program adjustments or methods for cleaning and disinfection prior to bringing components online

Examples of Partial Operation for Cooling Tower Systems

Intermittent or “On Demand” System: Cooling tower system transitions in and out of heat load due to intermittent demand for cooling over short periods.

• Facilities that may need cooling only on some days, such as religious institutions, theaters, or concert venues.

Reduced or Staged Load: Some system components are isolated and offline, while other portions are under heat load.

• Commercial buildings with partial vacancy (part of system may be isolated from the rest).
• Mixed use building with residential and commercial tenants that run on different cooling demands, such as commercial tenants requiring year-round refrigeration while residential areas need seasonal comfort cooling.
• Cooling tower system components with cycled or staged operations.
• Heat exchangers/chillers with modular cycles of operation.
• Cooling tower equipment used only during peak summer operation.
• Pumps or other equipment operating in a lead/lag manner.

Wet Lay-up: Intentionally maintaining cooling tower system components wet without being under heat load and without water flowing through the cooling tower equipment (no water spray or mist released).

• Intentionally maintaining filled or partially filled system components such as condensers, cooling towers, heat exchangers, or chillers for rapid startup in the event of unseasonably warm weather or for sudden increase in cooling load such as emergency backup systems for data centers or other critical cooling.
• Large diameter piping or risers maintained full of water to prevent scaling and fouling that may lead to clogging and maintenance issues at seasonal startup.

Whether in full or partial operation, maintain your cooling tower system as required by NYC cooling tower regulations. The Health Department highly recommends continuous or at least periodic scheduled circulation of biocide treatment throughout the system.

The Health Department conducts unannounced, routine inspections of all New York City cooling tower systems. During an inspection, health inspectors evaluate cooling tower systems for compliance with New York City regulations found in Chapter 8 in Title 24 of the Rules of the City of New York and NYC Administrative Code Section 17-194.1.

Provide Health Department inspectors prompt access to the cooling tower system, including treatment rooms, equipment, MPP, and required records. Health inspectors will arrive at your building and request to meet with the building manager, lead engineer, superintendent or whoever is responsible for cooling tower maintenance on site.

Health Department inspectors will review records, conduct a visual inspection of the cooling tower system, check registration information, and may collect a water sample. The inspection findings will be captured electronically.

All records must be provided while the inspector is on site. Records will not be accepted after the inspector has left the premises.

After the Inspection

Once the inspection is completed, the health inspectors will review the inspection report (IR) with an on-site representative and obtain their signature before leaving. The IR will be emailed to:

• The cooling tower system permission owner
• Building permission owner
• On-site representative
• Building owner

The Health Department will send a summons subject to civil penalties for any violation seen at the time of inspection to the building owner’s mailing address listed by the Department of Finance.