Is your cooling tower safe for the summer? A quick guide to NYC Local Law 77 and NYS Title 10

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June 21, 2023
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Is your cooling tower safe for the summer? A quick guide to NYC Local Law 77 and NYS Title 10

By now, you’ve dusted off your flip flops and (hopefully) prepped your home for the upcoming summer season. The one element you want to make sure hasn’t been forgotten? Your building’s cooling tower.

Cooling towers are crucial components in many HVAC systems, especially in big buildings. In 2015, new regulations were introduced in New York City (NYC) and New York State (NYS), which require building owners to adhere to strict guidelines for maintaining and operating these systems. In this article, we’ll lay out the basics on cooling towers, including maintenance requirements and the main regulations governing their use.


  • Cooling towers are crucial for HVAC systems in large buildings and must be properly maintained.
  • NYC and NYS have regulations (Local Law 77 and Title 10) to ensure safety.
  • Cooling tower requirements include regular inspections every 90 days and before seasonal startup.
  • Summertime hyperhalogenation is required between July 1 and August 31 to prevent bacterial growth in summer.
  • Legionella testing must be conducted every 90 days, and any presence of bacteria must be reported.
  • Expert assistance is available for cooling tower maintenance and compliance.
  • Building owners must develop a maintenance program based on ASHRAE 188-2015.
  • Cooling towers must be registered with both NYC and NYS.
  • Cleaning should be done at least twice a year, and water quality parameters should be monitored regularly.
  • Proper maintenance and compliance with regulations are crucial for safe operation.

What’s a cooling tower?

A cooling tower is a unit that recirculates water to cool the interior of a building. They’re often found inside or on top of large high-rise buildings and can consist of multiple towers and/or “cells” recirculating the same water.

Cooling tower requirements

This is where things get tricky… everyone loves to crank the a/c in the summer. Cooling towers work by evaporating water, and those droplets can enter your home or impact the surrounding environment, which can cause problems. If a cooling tower’s not properly maintained those water droplets can cause bacterial growth, and sometimes, the bacteria Legionella. Remember that outbreak of Legionnaires’ disease in the city last year (and a couple years before that)? Yep - that’s from Legionella.  So, in August 2015, new requirements for building owners with cooling towers were introduced in NYC (Local Law 77 of 2015) and NYS (Title 10 of NYCRR, Part 4 "Protection against Legionella''). In 2020, LL77 was amended to include summertime hyperhalogenation.

Below are the highlights of the city and state regulations that you’ll need for the summer season. For the full rundown, visit Building owners should consult both sets of regulations to ensure total compliance, as some regulations may be unique to either the City or the State.

  • Inspection by a qualified person (typically a cooling tower specialist) every 90 days and prior to seasonal startup. All inspections must be logged digitally in accordance with NYC Local Law 76.
  • Summertime hyperhalogenation: a yearly dose of chlorine- or bromine-based biocide to prevent bacterial overgrowth in the heat of summer. Done between July 1 -August 31.
  • Testing every 90 days for Legionella
  • If tests show presence of Legionella bacteria in the cooling tower, building owners must notify the relevant authorities as per the City and State regulations.
  • Existing cooling towers must already be registered with NYC and NYS, and the same goes for new towers before operating.
  • If there are multiple towers for one building, they must be registered separately.
  • Cleaning minimum 2 times a year
  • Regular monitoring of water quality parameters, temperature, pH, conductivity, and biocide indicators as outlined by NYC Department of Health (DOH)
  • Both NYS and NYC require building owners to develop and implement a cooling tower system maintenance program according to the ASHRAE 188-2015 standard.

Final thoughts

A cooling tower requires constant upkeep, but there’s no need to feel overwhelmed! Your property manager should be leading this effort with the right experts. If you think your property manager might have overlooked your cooling tower, we’re here to help. If you already work with Daisy, your cooling tower maintenance is under control. Taking these steps will ensure everyone is safe and comfortable for the summer and beyond.

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