NYC Cooling Tower Compliance: Your Guide to Local Law 77 & 159
Prepare for Stricter NYC Cooling Tower Rules. As of May 7, 2026, Local Law 159 mandates monthly Legionella testing for all registered cooling towers, a major change from the current 90-day requirement under Local Law 77. Building owners must adapt to this new, more frequent testing schedule to stay compliant and avoid significant penalties.
Donnelly Mechanical and our strategic partners provide complete cooling tower services to ensure you meet every requirement under LL77 and the upcoming LL159. From developing your official Maintenance Program and Plan (MPP) to performing all required inspections, cleaning, and testing, we are your trusted partner for NYC cooling tower compliance.
Local Law 77 vs. Local Law 159: What’s Changing?
Local Law 159 of 2025 was passed to increase the frequency of Legionella testing, providing a more proactive approach to public health and safety. Here is a direct comparison:
| Requirement | Local Law 77 (Current) | Local Law 159 (Effective May 7, 2026) |
|---|---|---|
| Legionella Sampling | Every 90 days | Every month |
| Compliance Inspections | Every 90 days | Every 90 days (no change) |
| Maintenance Program & Plan | Required | Required (no change) |
| Annual Certification | By November 1 | By November 1 (no change) |
| Recordkeeping | 3+ years | 3+ years (no change) |
Donnelly’s Cooling Tower Compliance Services
Cooling Tower Mechanical Maintenance & Repair
Our expert technicians provide comprehensive maintenance and repair to keep your cooling tower system running safely and efficiently, from routine service to emergency repairs.
Cooling Tower Maintenance Plan & Inspection Services
We develop your DOHMH-compliant Maintenance Program and Plan (MPP) and perform all mandated compliance inspections, water treatment, and testing — including the new monthly Legionella sampling required by Local Law 159.
Full NYC Cooling Tower Compliance Checklist
The following requirements apply to all building owners with cooling towers, evaporative condensers, or fluid coolers in New York City:
| Requirement | Details |
|---|---|
| Registration | Register all systems with the NYC Cooling Tower Registration Portal before first use. |
| Maintenance Program & Plan (MPP) | Retain a qualified person to develop and implement a written MPP compliant with ASHRAE Standard 188. |
| Inspections | A qualified professional must conduct compliance inspections every 90 days and before each seasonal start-up. |
| Legionella Testing | (New as of May 7, 2026) Legionella sampling must be conducted monthly while the tower is operational. |
| Cleaning | Systems must be cleaned at least twice annually by a qualified professional. |
| Disinfection | Requires biocides applied by a commercial pesticide applicator with a NYS DEC Category 7G certification. |
| Annual Certification | By November 1 each year, certify via the portal that all required tasks have been completed. |
| Recordkeeping | Retain all maintenance, inspection, and test records for at least three years. |
NYC Cooling Tower Registration & LL 77 Resources
NYC Cooling Tower Registration Portal
Click Here
Maintaining NYC Cooling Towers
Click Here
Legionnaires Disease
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