With Legionnaires’ cases rising, Prevent Legionnaires urges New York to expand from end-use to source-to-tap strategy

As New York City battles a growing outbreak of Legionnaires’ disease in Central Harlem, the Alliance to Prevent Legionnaires’ Disease is calling on state and city leaders to abandon what it terms a narrow, ineffective response strategy and adopt a comprehensive water management approach. The nonprofit’s statement follows the NYC Health Department’s August 6 announcement confirming 67 diagnosed cases and three fatalities since July 25, 2025, in the Central Harlem cluster — a sharp reminder of the risks posed by legionella, the waterborne bacteria responsible for the illness.

The outbreak is renewing scrutiny of Local Law 77 (2015), a legislative framework enacted in the wake of earlier Bronx-based Legionnaires’ clusters that focused on registering and inspecting cooling towers. A decade later, the city’s case numbers remain among the highest in the country. Experts affiliated with Prevent Legionnaires say this underscores systemic gaps in the current policy, which focuses almost exclusively on end-user equipment while overlooking upstream water quality threats originating from source water and distribution system disruptions.

Why is the Central Harlem outbreak renewing debate over New York’s Legionnaires’ law?

The current Central Harlem cluster comes on the heels of one of New York City’s most intense summer rainstorms in recent years, and disease prevention experts are pointing to a pattern. On July 14, just 11 days before the first cases were reported, the city experienced flash flooding that overwhelmed infrastructure, especially in Harlem. According to Mayor Eric Adams and the NYC Department of Environmental Protection, it was the heaviest rainfall in the borough since Hurricane Ida.

Numerous peer-reviewed studies have shown a correlation between heavy rainfall events and increased incidence of Legionnaires’ disease. The reasoning is hydrological: rainfall and storm surges disturb settled legionella colonies in natural water bodies and infrastructure, potentially allowing the bacteria to enter municipal water systems. Given the incubation window for Legionnaires’ disease — typically 10 to 14 days — experts such as Bob Bowcock, a water quality specialist and board member at Prevent Legionnaires, argue that environmental disturbances like the July 14 storm may have triggered the latest outbreak.

In his statement, Bowcock emphasized that Local Law 77’s exclusive focus on cleaning and monitoring cooling towers, while necessary, fails to address systemic vulnerabilities. “The growing outbreak in Harlem is further evidence the current approach pursuant to a local law (77-2015) is ineffective in curbing the rising incidence of this disease,” he said. “The data speaks for itself: since the law’s enactment, New York City has experienced record-high cases of Legionnaires’ disease, continued outbreaks, and rates among the highest in the country.”

What are experts proposing to replace Local Law 77’s narrow focus?

At the heart of the critique is the idea that Legionnaires’ is not primarily a facilities management problem, but a broader water quality issue. The Alliance to Prevent Legionnaires’ Disease advocates for a “source-to-tap” strategy — one that involves proactive monitoring and treatment of water systems from their origin all the way to residential and commercial endpoints.

In this model, water suppliers would be required to test for and mitigate legionella at earlier stages in the distribution system, not just after the water has reached buildings. This could involve updated treatment protocols, additional filtration requirements, routine surveillance of mainline infrastructure, and more detailed investigation protocols after environmental events such as major storms, hydrant flushing, or pipe bursts.

“Effective prevention begins at the water source and distribution system,” Bowcock added. “When there are cases, officials must conduct thorough investigations which look at all potential sources — including the water system — for recent disruptions that can cause legionella bacteria to enter our home and building plumbing systems.”

Advocates argue that a more systemic strategy, though complex, would be significantly more effective in protecting public health, particularly for vulnerable populations such as the elderly, immunocompromised individuals, and residents of lower-income neighborhoods that often bear the brunt of infrastructure degradation.

How has New Jersey responded differently — and why are advocates pointing to it?

Much of the Alliance’s criticism of New York is framed in contrast to its neighbor New Jersey, which passed a sweeping source-to-tap law for Legionnaires’ disease in 2023. That law, Senate Bill 2188, mandates full-lifecycle surveillance of waterborne bacteria from the utility level through to the building level and will go into effect in May 2026.

One of the most vocal advocates for the New Jersey law was Gwen Hanlon, whose husband Kevin died of Legionnaires’ disease in 2017 while undergoing cancer treatment in a New York City medical facility. In the current statement from Prevent Legionnaires, Hanlon expressed anguish that nearly a decade after her husband’s death, families in Harlem are enduring a similar tragedy under an unchanged regulatory regime.

“To see yet another outbreak which has sickened so many and knowing three people have lost their lives makes us feel both devastated… and angry to see that it appears that nothing has changed since our experience,” she said. “This is not comprehensive or proactive, but rather reactionary and limited. As a NJ resident who helped to enact Senate Bill 2188 last year, I call on New York to put a source-to-tap policy in place in order to ensure that no more families must go through what I and those in New York are being forced to experience.”

What are the public health and economic risks of continued inaction?

The U.S. Centers for Disease Control and Prevention (CDC) estimates more than 8,000 cases of Legionnaires’ disease are reported annually, though actual incidence may be higher due to underdiagnosis. Outbreaks account for only 4% of cases, while the remaining 96% occur as isolated or endemic cases, which makes surveillance more challenging and necessitates proactive infrastructure planning.

Fatality rates remain troubling. On average, one in ten individuals who contract Legionnaires’ disease will die. Among immunocompromised populations — including those undergoing chemotherapy, people with chronic lung conditions, and the elderly — that figure is even higher. This has ramifications not only for public health systems, but for hospital liability, insurance payouts, and urban water management funding.

Health economists have also flagged the costs of hospitalization for Legionnaires’ patients, which often exceed $30,000 per case in severe instances. Multiplied across dozens of patients per cluster, such outbreaks can rapidly strain emergency medical budgets in underserved areas.

Moreover, persistent clusters damage trust in municipal utilities. As infrastructure ages and climate-change-driven weather events increase in frequency, the risks tied to neglected water systems are projected to grow. Stakeholders believe now is the time to implement broader reforms, not after another mass casualty event.

How are city officials and health agencies responding?

As of August 7, 2025, the NYC Health Department has not publicly linked the Harlem outbreak to any specific infrastructure failure or environmental event. The agency has confirmed the ongoing investigation and urged residents in the affected area to seek medical attention if they experience symptoms such as cough, fever, chills, or difficulty breathing — hallmark signs of Legionnaires’ disease.

No official policy changes have yet been announced in response to Prevent Legionnaires’ recommendations. However, the advocacy group’s statement is likely to add pressure on Mayor Adams’ administration and the Department of Environmental Protection as they assess the root cause of the cluster.

City Council members representing Harlem and Upper Manhattan have also begun raising concerns about systemic water infrastructure issues disproportionately impacting Black and Latino communities, which make up a majority of the neighborhood’s population. Several legislators have cited the outbreak as evidence that city health codes must be updated in light of both epidemiological and environmental research.

What comes next in the push for a new prevention framework?

With the Central Harlem cluster still under investigation, public health experts and advocates are urging the city to follow New Jersey’s lead by initiating legislative reforms. Whether such reforms will materialize before another deadly outbreak occurs remains uncertain.

In the meantime, Prevent Legionnaires continues to amplify its message through national media and direct outreach to policymakers. The group insists that without a proactive water-quality model addressing source-to-tap risks, outbreaks like the one in Harlem will become increasingly frequent — and deadly.

“The innocent are paying the price for the city’s narrow approach,” Bowcock concluded. “This is a water system issue, and until New York addresses it as such, families will continue to suffer.”