Does the Risk of Legionnaire’s Disease Rise When There’s Lead in Your Water?


Ongoing monitoring shows that lead levels in Flint, Michigan’s water are dropping and getting closer to meeting federal safety standards. That’s some much-needed positive news for the community. But there’s still work to be done.

Now, researchers are starting to check residential hot water heaters in Flint homes for Legionella. Legionella grows best in warm water and hot water heaters are known to be a potential breeding ground.  One researcher suspects that the problems with Flint’s water supply might have resulted in higher-than-normal amounts of Legionella, putting the city’s hot water heaters at a greater-than-average risk.

Virginia Tech professor Dr. Marc Edwards believes that – in addition to elevated levels of lead – high iron in Flint’s water was partly to blame for the water crisis. His research has shown that high iron levels in water can remove disinfectants like chlorine, allowing harmful bacteria to grow. This includes bacteria like Legionella, which causes Legionnaire’s Disease. Legionnaire’s disease is a lung infection caused by breathing in contaminated water droplets – something that might happen when you’re having a shower, for example.

There’s no solid link to the area’s water supply as yet, but a recent news report says there has been an increase in rates of Legionnaire’s disease in the Flint area based on the number of cases health officials have reported over the past couple of years. However, another recent news item reports that a sampling of water in large and small buildings shows a decline in Legionella bacteria readings from October to March, so it would appear things are headed in the right direction.

It’s not just Flint’s water heaters that are at risk when it comes to Legionella – the right conditions can cause the bacteria to develop in any residential hot water heater. Water heater temperatures under 50 degrees Celsius may increase the risk of Legionnaires’ disease due to bacterial growth in the tank, and the risk is particularly significant between 40 and 50 degrees Celsius.


Stacey Pineau

Clearly explaining complex topics has been Stacey’s focus for close to 25 years now. She helps plan how best to reach the right people, then works to provide them with relevant information that’s easy to understand. Stacey is a team player with an entrepreneurial spirit. She has broad experience that spans the private and public sectors. A lover of words, Stacey has a slightly irrational love of the library and a personal collection of way too many books and magazines. She lives in Fredericton with her husband Ray, their two children and dog Scouty.

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