New York City health officials said water supplies in buildings linked to the outbreak in the Bronx were “unaffected by legionella” without ever testing the water systems, according to city health department sources. Neither the buildings with cooling towers that tested positive for legionella nor the workplaces or residences of the 115 New Yorkers with confirmed cases of the disease had their water supplies sampled for the infectious bacteria.

This means officials could not know for sure if the water in those buildings was safe, some experts say.

City health spokespeople refused to say whether they tested any of the buildings’ water supplies after being asked multiple times, suggesting only that the buildings did not require testing. If the water had been contaminated with legionella, the logic goes, multiple illnesses would have been reported in a single building, but they have not, officials say. “The cases in the South Bronx outbreak do not share a common indoor water source,” a health spokesperson said.

However, medical and public health experts insist that the buildings’ general water supply should have been tested. Federal health and safety guidelines also call for such testing.

Dr. Stephen Edberg, a public health microbiologist at Yale University who invented the Colilert test, the standard test for bacterial contamination in drinking water, is concerned that the disease-causing bacteria could be in the buildings’ water supplies. The only way to be sure legionella is not posing a risk, he said, is to test for it.

“I don’t see why you wouldn’t test them,” Edberg said of the buildings’ water supplies. Since he is not directly involved in the outbreak investigation, he could not comment on the likelihood of contamination in those buildings. But if investigators don’t look, Edberg said, they will never know. “If you don’t test for it, it’s ridiculous.”

The city’s hypothesis is that the legionella is being spread by mist drifting off cooling towers on rooftops, which passers-by then breathe in. Officials have said from early on that the cooling towers are the sole source of the legionella outbreak.

Officials distributed fact sheets to the media that read: “New York City’s drinking water supply and other water features, like fountains, shower heads and pools, are safe throughout New York City and are unaffected by legionella. Water towers are unaffected by legionella.”

Dr. Victor Yu, a top legionella expert with 30 years of experience who defined the clinical syndrome of Legionnaires' disease in 1982, cast doubt on these assertions. He said legionella outbreaks virtually always stem from a building’s drinking water supply.

“You’ve got to look at the water,” Yu said. “Legionella is actually coming through the city water supply, but in very low numbers.” And in such low numbers, the bacteria usually won’t make people sick. But legionella thrives in warm water, and when it multiplies to large numbers—often in warm reservoirs like water heaters or hot tubs—it can infect susceptible individuals such as elderly smokers or older patients with chronic illnesses.

Public officials find it difficult to explain this nuance to the general public. So to avoid panic, Yu reasons, they avoid the discussion altogether by pinpointing a single source—in this case, the cooling towers. Yu suspects the outbreak was caused by Bronx residents drinking tap water, possibly from their own homes.

If the city’s health department is willing, Yu’s lab—the Special Pathogens Laboratory in Pittsburgh, Pennsylvania—has offered to test the drinking water of all the legionella-linked buildings for free. The lab is considered among the best in the world for legionella testing. City health officials did not comment on the offer.

While it’s possible to inhale the bacteria into the lungs and become infected, Yu’s epidemiological studies have shown that the disease is primarily contracted by aspirating, or choking so water goes into the lungs—one reason elderly smokers are most at risk.

Marvin Montgomery, 36, who worked near Lincoln Medical Center passing fliers out to people on the street, is not sure how he contracted Legionnaires' disease. He could have been infected by the hospital’s drinking water or its cooling towers, his lawyer said. The hospital is one of the 18 buildings with cooling towers that have tested positive for legionella so far.

“I thought I was a goner for sure,” Montgomery told the Daily News from his hospital bed last week. “My heart was beating rapidly. It seemed like there was nothing they could do. I was strong as an ox. Now I’m a weak duckling.”

Montgomery regularly drank from the hospital’s drinking fountains and used the hospital’s bathrooms, where he would splash water on his face. He blames the city for his Legionnaires' disease and has filed a claim to sue for $10 million. 

His lawyer, Adam Slater, says he suspects the city was not following federal guidelines for maintaining the hospital’s cooling towers. “The bottom line is they’re supposed to test twice a year,” he said. “And I’m going to bet just about anything that was not happening.”

The Occupational Safety and Health Administration publishes guidelines for how employers should manage the risk of legionella contamination in building water systems, including regularly cleaning and disinfecting cooling towers at least every six months.

The OSHA guidelines also lay out proper water testing procedures in the event of a legionella outbreak in a cooling tower. The building water supply to the cooling tower should be tested before decontaminating the cooling tower, according to the OSHA manual.

OSHA officials cautioned that these protocols are meant to support investigations and are not enforceable regulations or standards.

Still, OSHA urged the importance of thorough investigation. “It is important not to overlook any potential water sources in the building,” a spokesperson said, noting that legionella contamination had been found in seemingly unlikely locations before. “The investigator is trying to determine the source of legionella: Is legionella coming from the water source, is it being amplified in the system (and if so where)?”

Dr. Edberg said he has been sparring with a top city health official—his former student—for the last month over the department’s decision not to test the general water supplies in the legionella-linked buildings, particularly the rooftop drinking water tanks.

In media reports, there has been some confusion between these water tanks and cooling towers—they are different. Cooling towers are large, boxy metal structures often on rooftops that can be part of the ventilation, heating and air-conditioning systems of larger buildings. Water tanks, or water towers, are the wooden or metal water reservoirs that often hold drinking water in buildings over six stories tall.

A New York Times investigation by this reporter in 2014 found that rooftop water tanks can become contaminated. Some tanks contained E. coli, a bacterium found in feces that is used to predict the presence of viruses, bacteria and parasites that can cause disease. The presence of E. coli suggested that animals had gotten into the tanks, experts said.

“It seems as though, if the cooling towers are contaminated, the water towers would be contaminated,” Edberg said, suggesting a link between the two systems. “As far as I’m aware, from the deputy director (of the city health department), they have not cleaned the water towers. And I’ve been on her case back and forth about that.”

Health officials have rejected the idea that the legionella contamination originated from water tanks, stressing that they are “totally separate” systems. While it is true they are separate in some city buildings, cooling tanks and water tanks are frequently linked in others.

Steven Silver of American Pipe and Tank, which services both cooling towers and water tanks in New York City, says water tanks supply water to the cooling towers in some, but not all buildings. And he says both cooling towers and water tanks can be easily contaminated if they are not regularly tested, cleaned and maintained.

“The cooling towers themselves are absolute breeding grounds for Legionnaires' disease,” Silver said. “Like a busted-open roof cover on a water tank is a prime habitat for pigeons.” 

In a letter to New York hospital administrators in July 2005, the state Department of Health noted how intractable legionella contamination can be once it is found in a building’s water system. “Legionella bacteria are naturally occurring, ubiquitous aquatic organisms,” the letter notes. “Complete eradication of Legionella is not feasible and re-growth will occur.”

In response to the outbreak, Mayor Bill de Blasio ordered every cooling tower in the city cleaned last week, just as Gov. Andrew Cuomo announced free testing for any cooling tower in the state.

But as water treatment specialists and state health inspectors rush from rooftop to rooftop, Dr. Yu believes the governor’s testing plan will not be effective in preventing outbreaks. 

“They have identified the wrong source,” Yu said.

In another effort to head off future outbreaks, the City Council is rushing to pass new regulations into law. These new regulations are based upon an industry standard, called ASHRAE 188-2015. Dr. William McCoy, who co-wrote the standard, noted that it focuses equally on building drinking water systems and cooling towers. This is important because cooling towers are often “implicated in cases that, in reality, were caused by legionella from building water systems they were not treating.”

E.D. Cauchi contributed to this report.