The largest outbreak of Legionnaires’ Disease may be due to insufficient heating of hot water

Insufficient heating of the hot-water system in Miami Valley Hospital’s new 12-story addition was the primary reason for the largest outbreak of Legionnaires’ disease in Ohio since 2004, according to the hospital.


The outbreak of Legionnaires’ disease at the hospital in February and March highlights an unintended result of plumbing codes that could put vulnerable populations like hospital patients at risk.


In certain cases, an outbreak of Legionnaires’ disease can be an “unfortunate consequence of something that’s intended to protect public health,” said Dr. Lauri Hicks, a medical epidemiologist with the Centers for Disease Control and Prevention.


In an exclusive interview this week with the Dayton Daily News, hospital officials announced the cause of the outbreak, which sickened 11 patients and may have contributed to the death of one of those patients.


Prior to occupancy of the $135 million patient tower on Dec. 28, a construction team made sure the water that supplied showers and faucets was heated to no more than 120 degrees Fahrenheit, as required by the Ohio Plumbing Code, hospital officials said.


Hospital officials said they had planned to heat the water to 130 to 140 degrees, but were told to lower the water temperature to comply with code requirements, which are intended to prevent scalding.


“When the codes recommended a certain water temperature, those codes didn’t contemplate a vulnerable population” and its susceptibility to waterborne bacteria such as Legionella, said Jennifer Theibert, the hospital’s risk-management director. The acutely ill are more susceptible to contracting Legionnaires’ disease than the general population.


State codes like Ohio’s that require hospitals to keep water temperatures at 120 degrees are “irresponsible,” said Tim Keane, who was hired by Miami Valley Hospital after it detected its first cases of Legionnaires’ disease in late February.


“One of the primary drivers of Legionella in health care are codes,” Keane said.


Such codes aim to minimize the risk of scalding by requiring caps on water temperatures. But Keane claims the risk of hot water systems becoming colonized with Legionella bacteria is far greater than those associated with scalding.


Legionella bacteria begin to die at 108 degrees Fahrenheit, according to the CDC. But not all of those bacteria die at that temperature, and water typically begins to cool as it moves away from the heating source, the CDC’s Hicks said. In large buildings, the temperature can drop as much as 10 to 20 degrees in some parts of the hot water plumbing system. Consequently, “bacteria may be thriving in the pipes near the shower head, but not in the hot water heater itself,” Hicks said.


Miami Valley Hospital is now heating water in the entire hospital to 140 degrees, and has the ability to mix hot and cold water at faucets and other points where people come in contact with the water to reduce scalding risks.


The hospital also has installed a hyperchlorination system to “make sure this never happens to us again,” said Barbara Johnson, the hospital’s chief operating officer.


Reduced water flow in parts of the new addition’s plumbing system also contributed to the outbreak.


Legionella is found in most water sources, but is usually contracted by breathing in mist from water that contains high concentrations of the bacteria. Legionnaires’ disease is not contagious.


The hospital spent about $61,000 to eradicate Legionella from the hot water system. It declined to release both its report on the outbreak and a white paper summarizing what it’s learned.


The hospital has received inquiries about the outbreak from attorneys representing patients who had Legionnaires’ disease, but no legal action has been taken against the hospital, Theibert said.


Contact this reporter at (937) 225-7457 or