New York City to strengthen cooling-tower inspections after recent legionnaires outbreaks

New York City officials said they will increase oversight of cooling towers after two severe legionnaires’ disease outbreaks that killed 18 people and sickened more than 190 residents in the past two summers. The city will allocate an additional $13 million in the 2027 fiscal year to hire 23 water ecologists and to require building owners to test tower water every 31 days while the systems are operating, a frequency described as the strictest in the United States.

Governor Kathy Hochul signed legislation mandating biannual certifications of cooling towers and raising fines for violations that cause serious illness or death from $10,000 to $12,500. City council member Virginia Maloney also proposed a bill that would require owners to clean towers at least three times a year, up from the current twice-annual schedule.

"We can all do better in preventing legionnaires’ disease," said Dr. William Schaffner, an infectious-diseases expert at Vanderbilt University School of Medicine.

"The thing about a cooling tower is that it’s not just the people in your building that are affected," said Amy Pruden, a civil- and environmental-engineering professor at Virginia Tech.

"With any regulation, there is a carrot and a stick," Pruden added, noting that penalties are intended to encourage proper maintenance.

The city’s health department reported that testing of cooling-tower water fell from 3,190 inspections in the first half of 2017 to 1,167 in the same period of 2025, a decline attributed to staffing shortages. In the latest investigation, 59 of more than 180 sampled towers tested positive for legionella, including sites such as the Guggenheim Museum, residential buildings, a grocery store and a private school.

Legal actions have been filed by victims of the 2025 Harlem outbreak and their families against the city, its health agency and contractors responsible for tower maintenance. Attorneys representing the plaintiffs emphasized the need for owners to account for the public health risks associated with cooling-tower operation.

Experts warned that rising temperatures linked to climate change could increase reliance on air-conditioning systems, creating conditions that favor legionella growth. "The more heat it’s trying to reject, the warmer that water gets and the greater likelihood you have of legionella," said Jeffrey Siegel, a civil- and mineral-engineering professor at the University of Toronto.

Despite projected budget shortfalls, officials and scholars argue that investing in preventive measures could reduce the costly health impacts of future outbreaks.