Cooling towers sit under more regulation than almost any other piece of equipment a New York building owner operates, and the requirements governing them changed again this spring. Registration, a written maintenance program, routine inspection, laboratory testing and annual certification all apply, and they attach to each tower rather than to the building. The 2026 season has been the first one running under a monthly testing requirement, and this fall brings the first shutdown and certification to follow it.

A cooling tower works by evaporating water, which releases a fine mist into the air around and above the building. Where Legionella bacteria have established in a system that is not well controlled, inhaling that mist can cause Legionnaires’ disease, a severe pneumonia that is treatable but can be fatal. Those bacteria multiply quickly in warm water that sits still, which is why the intervals are written as tightly as they are.

What Changed in May, and What Stayed the Same

A good deal stayed where it was. Compliance inspections by a qualified person remain on a 90 day cycle, weekly monitoring continues as before, and summertime hyperhalogenation between July 1 and August 31 is still required for any system operating in that window. Certification remains due by November 1, and each tower still needs its own entry in the city and state registries.

The Document Everything Else Hangs On

The maintenance program and plan is the spine of a compliance file, and inspectors read it first. It has to be developed by a qualified person, follow the manufacturer instructions for the specific equipment on site, and align with sections 5, 6 and 7.2 of ASHRAE Standard 188. The most common weakness we see is a plan that describes procedures nobody actually performs. Where a building already runs a preventive service and maintenance program, the plan is worth reconciling against it each season.

Startup and the Fifteen Day Window

Before a system that has been idle or untreated for five or more days returns to service, it has to be cleaned and disinfected no later than fifteen days before first use. The city startup procedures set out the sequence, which means removing biofilm and scale before an approved biocide is dosed to a verified residual. A pre-startup inspection follows, and the collection date for the post-startup samples goes into the city portal within five days. The underlying rule text also treats any tower coming back from replacement and upgrade work as a fresh startup.

When a Result Comes Back Elevated

An elevated reading is better handled as an active condition than as a filing obligation.

Culture takes several days to grow, so every result describes the tower as it stood on the collection date rather than on the day the number arrives. Table 8-1 in Chapter 8 sets the response for each result band, and the state rules add a layer of their own. A culture at or above 1,000 colony forming units per milliliter requires notification to the local health department within 24 hours, and lower results still trigger a treatment review and a retest. Our applicators are certified to apply biocide in cooling towers under the state requirements, so remediation can begin on the same emergency service call.

Shutdown and the November Certification

Seasonal shutdown involves a great deal more than switching off a pump, since the system has to be cleaned and disinfected per the plan and left in a condition that will not create a reservoir over the winter. The Health Department publishes operation and shutdown guidance covering the common configurations, and the shutdown itself has to be reported within five days. Certification by November 1 attests that each tower had a compliant plan and that the requirements were met all season, which is why it is worth signing against a reconciled file rather than from memory.

A Compliance Calendar for a Seasonal System

The rest of a building’s equipment runs on a schedule of its own, covered separately in how often commercial HVAC systems should be maintained, and tower performance sits inside the wider question of commercial HVAC energy efficiency.

Where Owners Usually Get Caught

Every one of those costs very little to prevent and takes a considerable amount of explaining afterward, particularly now that the Health Department inspects registered buildings on a rolling basis rather than on request.

Henick-Lane holds the full cycle for building owners across the five boroughs, so the record supporting a certification is built as the season runs instead of being reconstructed in October. That work runs across office, institutional and medical facilities and laboratories, and the project list shows where.

Reviewing a Tower File Before the Deadline

A gap discovered in October is far easier to address than one discovered during an inspection. If a tower changed hands, changed vendors or changed chemical programs this year, get in touch with our team online, call (718) 786-7277 or email info@henick-lane.com to arrange a review before the certification date arrives.