In a follow-up to a story last week of an increase of Legionnaires’ disease reported in the Bronx, New York, the NYC Health Department announced today the results of preliminary tests that show that the cooling towers at Co-Op City are contaminated with the Legionella bacteria.


Since December 2014, 12 cases of Legionnaires’ disease have been diagnosed among Bronx residents. Eight of the 12 recent cases have been diagnosed among Co-Op City residents.

The Health Department is continuing its investigation to determine if the cooling towers are the source of these recent cases. Although no determination has been made that the cooling towers are the cause of any reported case of Legionnaires Disease, the Health Department instructed River Bay to take immediate steps to decontaminate the cooling tower in order to minimize the risk.

The infected water is used to cool Co-Op City’s heating and electrical systems. The water in the cooling tower is self-contained and is separate from the water used by Co-Op City residents for drinking, cooking and bathing. The water at Co-Op City is safe to drink, bathe and cook with.

River Bay Corporation, which operates the cooling towers, has taken immediate steps to decontaminate the cooling towers. With the guidance of the Health Department, River Bay began disinfecting the cooling towers with chlorine on Jan. 10. River Bay has also shut down the cooling tower at Co-Op City to do physical cleaning, followed by more chlorination to control the growth of Legionella bacteria.

“The Health Department is concerned about this sudden increase in Legionnaires’ disease in the Bronx,” said Health Commissioner Dr. Mary Bassett. “We are conducting a thorough investigation and working closely with River Bay Corporation to minimize the public risk and to prevent future cases. I urge anyone with symptoms to seek medical attention right away.”

Co-op City (Cooperative City), located in the Baychester section of the borough of the Bronx in northeast New York City, is the largest cooperative housing development in the world.