NYC Cooling Tower Water Treatment
Cooling towers are the most heavily regulated water system in New York City — and for good reason. Poorly maintained cooling towers are the leading source of Legionella outbreaks in urban environments. In 2025, a Harlem outbreak linked to cooling towers killed seven people and triggered the passage of Local Law 159, which mandates monthly Legionella testing starting May 2026 with fines starting at $10,000 per violation. Acqua Treat has provided cooling tower water treatment and compliance services to NYC buildings since 1982. We know the regulations, we know the equipment, and we know what it takes to keep your building safe and compliant.
NYC Cooling Tower Regulations — What You're Required to Do
Under Local Law 77 (2015) and Local Law 159 (2025), building owners with cooling towers in all five boroughs must:
Register the cooling tower with NYC DOHMH and maintain a current registration
Have a qualified person develop and maintain a Maintenance Program and Plan (MPP)
Test for Legionella every 31 days during operation (monthly — effective May 7, 2026)
Monitor for heterotrophic bacteria weekly
Maintain daily water treatment records (pH, conductivity, biocide levels)
Clean and disinfect the tower at least twice per year
Perform mandatory summer hyperhalogenation disinfection between July 1 and August 31
Submit annual certification to the NYC DOHMH portal by November 1
Use only ELAP-certified laboratories for Legionella sample analysis
Notify DOHMH within 24 hours if Legionella results reach 1,000 CFU/ml or above
Retain all records for a minimum of three years
Our Cooling Tower Services
Acqua Treat offers two service levels — choose what fits your building and your team. We also offer support for DOHMH violations for all customers.
Full Service (we handle everything)
Our technicians visit your facility on a regular schedule and handle all chemical treatment, testing, monitoring, and compliance documentation. You don't need to think about it — we manage the program from end to end. Full service includes:
Regular site visits for chemical treatment and system inspection
Monthly Legionella sampling through an ELAP-certified laboratory
Weekly heterotrophic bacteria monitoring
3x/week water quality monitoring records and biocide treatment logs
MPP development and maintenance
2x/year cleanings and summertime hyperhalogenation
DOHMH reporting and annual certification filing
Emergency response for failed samples or DOH violations
Monthly Service (we complement your team)
Our technicians visit your facility on a regular schedule and handle chemical treatment, testing, monitoring, Legionella sampling and compliance documentation. Weekly heterotrophic bacteria monitoring and 3x/week water quality monitoring records and biocide treatment logs are handled by your team.
Supervisory Service (we support your team)
We provide chemicals, Legionella sampling, and other Local Law 77 and Local Law 159 on an as-needed basis.
Cooling Tower Cleaning & Disinfection
Under NYC regulations, cooling towers must be cleaned and disinfected at least twice per year — and additional cleanings are required any time Legionella sampling results trigger corrective action, or when a tower has been offline for five or more days. Our cleaning services include:
Full mechanical cleaning of basin, fill, distribution deck, and drift eliminators
Hyperhalogenation disinfection (including mandatory summer treatment, July 1–Aug 31)
Post-disinfection Legionella verification sampling
DOHMH-compliant documentation and reporting
Emergency disinfection for positive Legionella results — rapid mobilization available
Need a cooling tower compliance review, a cleaning, or help getting on top of the May 2026-effective Local Law 159 regulations? Contact us — we'll assess your current program and tell you exactly where you stand.