Reporting Requirements for Cooling Towers

Online comments: 9

• Ron F

  I appreciate the City’s commitment to protecting public health. However, I respectfully oppose the proposed amendment to require monthly Legionella testing of cooling towers (replacing the current 90-day requirement). This amendment is unnecessary, unsupported by evidence, and will impose undue financial burdens on property owners — especially residents of cooperatives and other multi-family buildings — without a proportionate public health benefit.

  1. Current Regulatory Framework Already Includes Frequent Monitoring and Maintenance

  Under existing NYC and New York State regulations, cooling towers are already subject to comprehensive oversight:

  Quarterly (every 90 days) Legionella sampling is required while towers are in use, and all sampling must be performed by certified laboratories.

  Owners must perform weekly heterotrophic bacteria sampling and routine system monitoring (e.g., water quality measurements multiple times per week), daily biocide treatment, and at least semiannual cleaning/disinfection events.
  These multi-layered requirements already serve to identify and control conditions conducive to bacterial growth before they escalate into outbreaks.

  The regulatory approach applied in NYC is already more stringent than many other jurisdictions (which typically require Legionella culture testing only quarterly while also emphasizing maintenance and water chemistry controls).

  2. Monthly Testing is Not Proportional to the Scientific Evidence on Legionella Risk

  Legionella bacteria are naturally present in the environment, and detection in cooling tower water does not necessarily mean that disease transmission will occur. In fact, many cooling towers test positive for Legionella at times without resulting in illness.

  Additionally:

  Legionnaires’ disease outbreaks are relatively rare events given the large number of cooling towers and the existing regulatory framework in place.

  The most widely referenced industry standards (e.g., ASHRAE 188) and many state programs do not require monthly culture testing as a baseline frequency — they focus on maintenance, water quality control, and reacting to conditions that promote growth rather than a rigid monthly test schedule.

  The City Council’s rationale for the more frequent testing is linked to a recent outbreak; but that outbreak — while tragic — was linked to failures in maintenance and remediation after positive tests, not necessarily to the testing interval itself. Furthermore, existing rules already require remediation and reporting upon positive results.

  3. Significant Financial Burdens on Property Owners and Residents

  Monthly Legionella testing will impose material new costs on buildings with cooling towers. These tests must be conducted by or under supervision of qualified professionals and submitted through certified laboratories.

  For cooperative boards and other residential property owners, increased testing costs will likely translate directly into higher maintenance fees, assessments, or rents at a time when affordability in NYC is already a critical concern. Many co-ops operate on thin financial margins, and increased mandatory testing could disproportionately affect seniors, low-income residents, and others struggling with the high cost of living in the city.

  The amendment’s financial burden falls on property owners rather than on operational factors that actually contribute to Legionella risk. A more targeted approach that focuses on maintenance compliance, enforcement of existing requirements, and better support for small property owners would be more equitable and effective.

  4. Alternative Strategies Can Better Balance Public Health and Economic Impact

  Instead of strictly mandating monthly testing, the City could consider:

  Enhanced enforcement of existing maintenance and inspection requirements to ensure that quarterly tests are meaningful and that positive findings are acted on promptly.

  Targeted testing protocols for buildings with known risk factors or prior violations rather than a blanket monthly requirement for all.

  Subsidized testing programs or technical support for small residential buildings to help them comply without undue financial strain.

  This approach would preserve public health protections without imposing unnecessary costs on owners and residents.

  Comment added February 12, 2026 11:21am

• Anonymous

  We already have excessive testing requirements which puts an extreme burden on property owners and whoever they pass their expenses onto. If you are following what is in place already, there should be no issues. We keep hearing about making this city more affordable while policies like this do the complete opposite.

  Comment added February 12, 2026 3:36pm

• Mitch Kaufman

  I really wish we could all focus on the time of the year when we are most at risk. Many cooling towers run 12 months per year. Of those towers, most operate in what is known as “free cooling mode.” Condenser water temperatures are as low as 40 degrees F. This is a temperature where the legionella bacteria do not thrive. Any cells that get into the atmosphere through misting are immediately killed by the ambient temperature of the atmosphere. Let’s focus on the summer months when condenser water temperatures are higher and where bacteria thrive. It is that time when these outbreaks occur.

  Let’s also consider what overexposure to chlorine does to equipment and to the environment.

  Comment added February 14, 2026 12:15pm

• Jack Glass, CIH - ALC Environmental

  The current version of this rule requires a certified laboratory to collect the samples. This is not a viable requirement due to the fact that nearly all laboratories only provide laboratory services. Currently, sample collection is performed by a large number of environmental consultants who also provide additional services at the site, such as inspection and disinfection.

  We strongly recommend changing the wording to: Sampling shall be conducted by firms and/or individuals experienced in the collection and management of environmental samples.

  Comment added February 18, 2026 11:09am

• Abraham Cullom

  1. The proposed rule defines startup as putting one or more cooling tower systems or components into operation. Cooling tower system components are then defined broadly and include pumps, filtration devices, chemical controllers, metering pumps, and other wetted equipment. Because some of these components may operate intermittently during normal operation, the current definitions could classify routine operational adjustments as system startups. The Department may wish to clarify that “startup” refers to placing a cooling tower system, tower cell, or circulation loop into operation following shutdown, commissioning, or extended inactivity, rather than activation of individual ancillary components.

  2. The proposed rule requires manual monitoring of disinfectant residual three times per day when bacteriological indicator results exceed the specified threshold, but “manual monitoring” is not defined. As written, the requirement could be satisfied by taking multiple measurements in rapid succession following a biocide addition, which may not demonstrate sustained treatment control. In addition, three monitoring events per day may be operationally burdensome for water treaters who service sites periodically rather than maintaining continuous on-site presence. Defining manual monitoring and clarifying a procedure that captures representative system operating conditions would improve implementation. Also, the HPC retesting requirement appears to provide a minimum waiting period, but not a maximum.

  3. The proposed changes close what I felt was the most important loophole in the previous version. Namely, that summertime hyperhalogenation Legionella samples could be counted as the quarterly sample for the summer. In practice, this meant that there was less known about Legionella growth in a tower during normal operating conditions in the most critical period of the year. The monthly testing requirements, at least during the summer, ameliorate this situation. If it is the intention that Legionella tests for hyperhalogentation can still serve for the routine monitoring sample, this should be clarified. If not, the sequence and spacing of samples should be clarified.

  Comment added March 4, 2026 11:02am

• Anonymous

  1. Can the Department provide a definition and example of a valve schedule with the required elements?

  2. Confirm “Compliance Inspections” of cooling systems remain at the frequency of every 90 days.

  3. Recommend that Table 8-1 include the hyperhalogenating instructions listed in Paragraph (5) of subdivision (f) of Chapter 8-05 as a footnote or within the Process column of the table.

  4. Define “manual monitoring” referenced in Table 8-1.

  5. Edit Table 8-2, Level 2 Response, second paragraph to include the words “for bacteriological indicator” after retest water to be clear on the type of retest.

  Comment added March 10, 2026 10:25am

• Carson Riggins

  I would like to thank the city for their commitment to prioritizing public health. I would also like to thank the city for the opportunity to comment and make my thoughts known on this proposed rule.

  I believe that requiring testing every 31 days is too frequent and has diminishing returns. The Department of Veterans Affairs has a guideline for testing for legionella bacteria in VHA buildings (Department of Veterans Affairs Directive 1061(4) Appendix D Section 4). This guideline calls for testing for cooling towers within 7 days of startup, and then quarterly testing of legionella bacteria in VHA buildings, which as I understand are usually healthcare settings. If the VA is only recommending testing every 90 days* for a healthcare facility, I find it unconvincing that the frequency for everyday New Yorkers needs to be increased to every 31 days.

  Thank you for considering my comment.

  Carson Riggins
  *Not including the first startup test
  Also please see attached a pdf copy of the VA Guidelines

  Comment attachment
  10614_D_2021-02-16.pdf

  Comment added March 10, 2026 4:43pm

• NYC-CTIS: NYC Cooling Tower Inspections & Services

  Regarding the proposed amendments to NYC Cooling Tower Regulations, we fully support measures that enhance oversight and improve public safety. At the same time, we respectfully raise a few concerns and hope the DOHMH will consider our specialized expertise in water treatment, consulting, and water safety when finalizing these updates.

  1. Key Requirement Considerations

  Annual certifications must be conducted by an independent third-party environmental consultant, (certifying vendor must not have any existing legal affiliation with the current water treatment vendor in care of the building).

  IMPORTANT RULE
  The third-party certifying agency (independent environmental consultant) must not have any existing legal affiliation with the building’s current water treatment vendor.

  REASON
  
Similar to elevator annual inspections (NYC Administrative Code 28-304), those inspections must be performed by a third-party agency not the company that performs the maintenance.

  POLICY LOGIC
  Third-Party Independent certifications prevent:
  self-certification bias
  falsified compliance
  underreported deficiencies

  2. Key Requirement Considerations

  Third-party independent inspections are required when Legionella levels reach Level 3 or higher. An independent environmental consultant would verify that the water treatment equipment is operational, confirm that the corrective action has taken place in accordance with the MPP, and collects a legionella sample; sampling will continue until Level 1 or below is achieved.

  IMPORTANT RULE
  The third-party certifying agency (independent environmental consultant) must not have any existing legal affiliation with the building’s current water treatment vendor.

  REASON
  
When a cooling tower is identified as having an elevated Legionella risk (Level 3 or Level 4), Heightened Monitoring of that system should be implemented to safeguard public health. For example, the NYC DOHMH frequently requires a Heightened Monitoring Plan (HMP) when a cooling tower or building water system shows evidence of increased Legionella risk.

  Policy Logic
  Third-Party Independent Inspections:
  Elevated Legionella levels (Level 3 or Level 4) indicate a higher risk to public health.
  Independent inspections ensure that corrective actions are verified objectively, eliminating potential conflicts of interest from vendors reviewing their own work.
  This policy mirrors the Heightened Monitoring Plan (HMP) process typically requested by NYC DOHMH, which is designed to implement more rigorous oversight for systems posing elevated Legionella risk.
  Continuous sampling and verification until Level 1 or below ensures that the system has returned to a safe operating condition, maintaining compliance and protecting building occupants.

  3. Key Requirement Considerations

  For an elevated bacteriological sample/dip-slide (over 10,000), the management and maintenance team must initiate monitoring of disinfectant residual one time per day until water treatment achieves a target biocide residual between the range of 1-3 PPM for two consecutive days.If two (2) consecutive days are not achieved within 3 days, collect a Legionella sample and continue to adjust. ORP data from a smart water treatment controller will meet the above noted requirement.

  IMPORTANT RULE
  For cooling tower water systems, the typical target free chlorine residual is guided by standard industry practices. While ASHRAE 188 does not specify a fixed ppm, most industry practice interprets a free chlorine residual range from 1-3 PPM as a typical operational target to prevent bacterial growth.

  REASON/POLICY LOGIC
  Daily monitoring over two consecutive days provides sufficient time to respond to elevated bacterial counts and confirm that the system maintains a sustained disinfectant residual within the recommended range. Maintaining 1–3 ppm free chlorine helps ensure effective disinfection, reduces the risk of Legionella growth, and provides a clear, verifiable indicator of system safety consistent with standard industry practices.

  REQUEST FOR CLARIFICATION
  Regarding Violation 24 RCNY §8-06(b)(2), which states that a sample must be collected prior to cooling tower start-up. This appears to conflict with Page 11, Section 25(b)(2), which requires sampling within 3–14 days after start-up. It also creates confusion with the current definition of “start-up,” which considers a system operational once water is present in the system.

  Comment attachment
  NYC-CTIS-2026-DOHMH-COMMENTS.pdf

  Comment added March 10, 2026 5:26pm

• EJD CWT NYC

  Subject: Public Comment on Proposed Changes to NYC Local Law 159 of 2025
  To the Relevant Agency / Rulemaking Committee:
  Below is a summary of my comments and concerns regarding the proposed changes under Local Law 159 of 2025. As an engineering and water treatment professional with over 40 years of experience, I share the common goal of all stakeholders—the public, building owners, operators, and water treatment professionals—in ensuring safe and well-maintained cooling tower systems. We all want effective, streamlined regulations that protect public health while recognizing the practical realities of facility management.
  Based on my professional experience, I urge the city to consider the following points:
  Implementation Timeline
  The proposed changes are to take effect on May 7th, yet the definitive version of the law and its associated rules remain incomplete. This leaves building owners and operators with less than six weeks to fully rewrite their maintenance programs and achieve compliance. This is a highly impractical timeline for an industry-wide transition.
  Risk Analysis and Scientific Basis
  I respectfully request to see the city’s risk analysis justifying these latest changes. How has the city concluded that the public would benefit tangibly? Building owners already possess the highest incentive to maintain zero Legionella counts to protect their occupants and limit liability.
  Furthermore, data from the CDC indicates that potable water systems, particularly in hospitals, are the primary source of most Legionnaires’ disease outbreaks. Outbreaks stemming directly from cooling towers are a much rarer occurrence. It is also well documented that Cooling towers are only a small part of the problem. Cooling towers were identified as the source in 22% of cases. Our goal is not to address the other sources at this time, except to mention they account for 78% of outbreaks.
  Winter Risk Assessment for Cooling Systems
  The risk of a Legionella outbreak is lower during winter months. But the city does not adjust its risk analysis or its requirements.
  Environmental Factors in Winter-
  In colder months, factors naturally inhibit the spread of bacteria and reduce the need for testing.
  • Lower Temperatures: Cooling towers operate at lower water temperatures, often staying below the high-concern threshold of 77°F (25°C) cited by the CDC.
  • Reduced Aerosolization: Cooling tower fans typically operate at reduced speeds or in the off position. This results in significantly smaller or non-existent drift plumes (where the bacteria could be) compared to peak summer operations.
  • Seasonal Trends: CDC data confirms that most outbreak investigations peak in the summer and early fall when ambient temperatures are highest.
  • Organic matter: It is typically lower in cooler weather.
  • Windows Barrier. Cooling towers are located outside, and individuals typically keep windows closed in cooler temperatures. This forms a barrier from cooling tower plumes.
  Cause of outbreaks-All sources: The Risk of Process and Human Failure
  The Results of CDC investigations are below for the cause of legionella outbreaks.
  • 65% Process Failure: Breakdown in the established water management plan, i.e. No water “Plan” or not complying with the plan.
  • 52% Human Error: Lapses in manual treatments or inspections.
  • 35% Equipment Failure: Mechanical issues with pumps or sensors.
  • 35% Unmanaged External Change: Unexpected shifts in water supply or environment
  It is worth noting that “insufficient testing of legionella did not make the list” is often not the hidden culprit behind these outbreaks. One can conclude that creating and strictly adhering to maintenance plans supported by well-trained operators and properly maintained equipment—is the most effective path to minimizing risk.
  All these preventive measures are already addressed and mandated under current law. Specifically, performing weekly bacteriological dipslides, weekly inspection and monitoring water parameters three times per week will reliably detect issues, provided these tasks are being completed. The rapid mitigation of detected issues remains the most critical step in preventing an outbreak.
  Environmental and Infrastructure Impact
  Has the city conducted studies on the environmental consequences of these new rules? Specifically, what impact will the mandated increase in biocide usage have on local wastewater treatment plants and the surrounding environment? It is a well-documented engineering reality that the increased use of halogen-based biocides accelerates corrosion and significantly reduces the lifespan of expensive cooling equipment.
  Outbreak Investigations and Geographic Disparities
  I also have questions regarding the data driving these regulations, specifically the two outbreaks linked to the cooling towers at Harlem Hospital. As referenced in the NYC Health Department press release, it is highly unlikely that Legionella amplified to dangerous levels in that system in less than 30 days. https://www.nyc.gov/site/doh/about/press/pr2025/health-department-closes-investigation-central-harlem-legionnaires-cluster.page
  Because this event seemingly triggered the new regulatory changes, I request that the city provide detailed information regarding its investigation into these past outbreaks, including the actual Legionella levels recorded in the tower. Furthermore:
  • How will these new changes address the specific areas where past laws and city attempts have fallen short?
  • Why have these outbreaks been localized in Central Harlem and the South Bronx?
  Industry Literature and Expert Consensus
  The water treatment industry has previously raised concerns about the efficacy of these types of localized regulations. In the Summer 2016 issue of the Cooling Technology Institute (CTI) Journal, Sarah Ferrari published an article titled “New York Legionella Regulations: Are They Missing The Boat?” (page 60).
  https://assets.speakcdn.com/assets/2793/2016summerjournalcti.pdf
  After reviewing the data, she concluded: “Ultimately a case is made that these new regulations will not have a measurable impact on reducing the incidence of Legionellosis.” It appears she was correct.
  Conclusion I urge the city to reconsider the implementation timeline and the scientific basis for these amendments. Effective laws must be driven by accurate, holistic risk assessments rather than reactionary measures.
  Thank you for your time, consideration, and dedication to public health.
  Sincerely,
  EJD CWT NYC
  Certified Water Technologist
  Chemical engineer

  Comment added March 12, 2026 1:54pm