Following NYC’s Local Law 159 of 2025, the DOHMH has proposed new cooling tower rules and requirements that clarify terms and add mandatory actions.
If these rules are adopted without changes, several updates would be made to Chapter 8 Title 24 – the section of RCNY that deals with cooling towers.
The hearing for these rules takes place on March 16th – you can view details for making comments or attending here on the city’s site. Until then, here are key highlights from the new law and the proposed rules:
Increased Testing & Inspections
Local Law 159 requires cooling towers to be sampled for Legionella every month instead of the current 90-day testing requirement.
The specific language in the proposed rules reads that “Legionella culture testing must be conducted no less frequently than every calendar month, with no more than 31 days between sample events, during cooling tower system operation.”
Based on the law, this increased testing will go into effect on May 7, 2026. Compliance inspections will also be conducted once every 90 days: “at least as frequently as every three months,” according to the verbiage in the law.
We expect the rules to be finalized before then, so stay tuned for news on the final adopted rules. Until then, we’ve summarized some of the big changes you can expect going forward below.
Testing Adjustments
There are several adjustments to Legionella testing, including some basic adjustments and new requirements.
Below is a portion of the adjusted law, with older struck portions in brackets and new words underlined:
- Each [inspection] test shall include [a test for] collection of a sample to evaluate the presence of microbes in the water of the cooling tower. The sample must be collected at least two days after any routine or corrective action required by the department, including the application of biocide, cleaning or disinfection. The department shall by rule establish (i) the targets and acceptable methods of microbial testing and laboratory analysis, (ii) the levels of microbes in cooling towers that are indicative of a maintenance deficiency requiring mitigation, including but not limited to maintenance to prevent potential health risks, and (iii) the levels of microbes in cooling towers that present a serious health threat and require [immediate] corrective action and reporting.
Additionally, Legionella sample tests must be conducted by a laboratory certified by the New York State Environmental Laboratory Accreditation Program (“ELAP”). Results must be “recorded in a final analytical report from the laboratory that includes a copy of the signed chain of custody and the laboratory’s ELAP certification number.” Test results must also be evaluated by the qualified persons and the management & maintenance teams to ensure Legionella control.
Another noteworthy change? Follow-ups to key results. Now, instead of certain results triggering different levels of action, any results greater than or equal to 10,000 CFU/ml would trigger a requirement for manual monitoring of the water treatment program. The proposed rules specify key actions here, now standardized for any result over 10,000 CFU/ml.
Timing Clarifications
The newly proposed rules also aim to define corrective timeframes that were previously listed as “immediate,” giving owners more clarity. Under the new rules, any system anomalies or problems must be recorded on the checklist, reported to the maintenance & management teams, and have corrective action taken within 24 hours.
Record Adjustments
Owners with cooling towers will have to continue to hold key records for at least 3 years, and provide them upon request. That said, language regarding documentation being required onsite has been struck, and there’s new language that clarifies how to handle electronic records:
If records are kept electronically, any such record requested by the Department at the time of inspection must be displayed on a digital device (e.g., computer or tablet) provided by the owner. Copies of such electronic records must be available in a format that is used by the Department and is generally commercially available, such as Portable Document Format (PDF), and must be submitted to the Department in a manner specified by the Department upon request
After the new rules are in place, teams using InCheck will be able to share records of key tests and monitoring on their electronic device, and provide automatic PDFs to the department afterwards.
General Updates
The proposed rules also clarify several definitions (cooling tower, maintenance program and plan, system shutdown, etc.) and add new ones (commissioning, operation, installation, etc.).
Here’s an example – compare the current definition of a cooling tower, and what the new rules propose:
We recommend reviewing the proposed rules for full definition changes, additions, and adjustments.
It also aims to reference updated documents like ANSI/ASHRAE, changing terms to “the latest edition” instead of noting a specific version. This lets future versions be referenced going forward without having to update the specific rules.
Here are other noteworthy updates required by the proposed rules:
- Require the preparer of the maintenance program and plan (MPP) for a cooling tower to annually certify the MPP
- No details here just yet – but certification would be “in a manner specified by the Department,” who must attest to key elements of the MPP
- Require the inclusion of operating configurations that result in low flow or no flow to a cooling tower risk management assessment
- Require that fill water for the commissioning or startup of a cooling tower be obtained from a municipal water supply
- Add requirements for commissioning, startup, and shutdown processes
- Clarify requirements for record production and retention, and require providing records to the department at the time of inspection.
Amended Penalty Schedule
The final changes to the rule see a hefty increase to penalties – in most cases doubling the fine for first time and repeat violations.
Penalties will also be added for the following issues:
- Failing to provide an annual plan preparer certification of the MPP
- Improper water treatment when cooling tower is operational
- Failure to report the date of a Legionella sample test
- Failure to report test date within 5 days
- Failure to report cooling tower operation, startup, and shutdown dates
Penalties for individual infractions will range from $250 – $4,000 going forward.
Best Practices
We definitely recommend connecting with your cooling tower vendors and service providers, and making sure everyone on your team (qualified and responsible persons, and general management) is aware of how changes will impact your routine.
You can also set up automated inspections and maintenance checks for cooling towers right in your InCheck account! Inspections are directly tied to each asset, and sent automatically to the right person on your team for completion as needed – for all the required timeframes in your MPP.
If you need to adjust any of your cooling tower SOPs or workflows post-May, we’re happy to help! Reach out to support@sitecompli.com or your Customer Success Manager to get started.
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