Over half the cooling towers in NYC Legionnaires' outbreak area issued violations in recent months

New York City health officials are still investigating a Legionnaires' disease cluster on the Upper East Side, and new records have put building compliance in the affected zone under sharper scrutiny.

Records reviewed by the New York Post show that 59% of cooling towers in the outbreak area received city health violations between March 2025 and March 2026. The report says the violations included failures to monitor, clean, use chemicals properly and submit Legionella test results.

The cluster has centered on Carnegie Hill and Yorkville, where the city has been testing cooling towers for signs of Legionella bacteria. Officials have said one or more towers in the area are the likely source and that the disease is not spread person-to-person.

The outbreak so far

AP reported on July 7 that the cluster had reached 23 reported cases, 17 hospitalizations and no deaths as of July 6. By July 9, the New York Post reported the city had confirmed 36 cases and 22 hospitalizations, according to the health department dashboard.

Those figures appear to reflect the timing of the reports rather than a direct contradiction. They do show the outbreak remained active as city inspectors continued environmental testing.

Officials have also said residents can keep drinking tap water, bathing, showering, cooking and using air conditioners while the investigation continues.

What the records show

The Post reported that eight towers in the affected area failed to collect, record, analyze or submit Legionella samples as required. It also said at least one cooling tower at 1511 Third Avenue tested positive for Legionella bacteria.

The records review adds a compliance angle to the public-health response. The issue is not only finding the source tower or towers, but also understanding how many buildings in the outbreak zone had already been missing required maintenance or reporting steps before the cluster emerged.

Cooling towers matter in Legionnaires' investigations because they can aerosolize contaminated water. Legionnaires' disease is a severe pneumonia caused by Legionella bacteria that spreads through inhaling contaminated droplets.

Pressure on the city

Council Speaker Julie Menin has urged immediate disinfection of all untested or unconfirmed towers. The Post reported that the Health Department said the request was under review.

The city has not publicly identified a single definitive source tower. Instead, inspectors and lab staff are still working through a wider set of towers in the area to narrow down where the bacteria may have spread.

The outbreak has also revived broader questions about oversight of building systems in dense neighborhoods, where multiple cooling towers can sit close together and affect large numbers of residents, workers and visitors.

What happens next

City teams are expected to keep testing and disinfecting towers while they search for the source or sources of the outbreak. Officials are also trying to determine whether additional towers need emergency treatment beyond those that have already tested positive.

Residents and recent visitors are being told to watch for symptoms and seek medical care quickly if they feel ill. For now, the main unresolved questions are which cooling tower or towers caused the cluster, how many buildings remain to be fully cleared, and whether additional cases will be confirmed as testing continues.