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Legionnaires’ Disease in Northern NJ: A Possible Link to Water Treatment Failures?

Recent months have brought a spate of Legionnaires’ disease outbreaks across northern New Jersey. In May, press outletsreported that at least three Newark residents had been diagnosed with Legionnaires’ disease. Three weeks later, officials in neighboring Union County announced that five people had died from Legionnaires’ disease, with more than twenty infected across the county. And back in 2018, Legionella bacteria was found in nine schools in West Orange and at least two cases were reported in 2018at a hotel near Newark airport. What is causing these outbreaks, and could they be related to Newark’s violations of numerous federal rules designed to protect drinking water? More information and a comprehensive state (and Centers for Disease Control & Prevention) investigation is needed.

What is Legionnaires’ Disease?

People can contract Legionnaires’ Disease after being exposed to Legionella bacteria, which can be found in the natural environment and in man-made water systems. Legionnaires’ disease—which primarily affects the elderly, smokers, and those with compromised immune systems—is a severe form of pneumonia, which can lead to septic shock, respiratory failure, acute kidney failure, and even death. Legionnaires’ disease can occur when people inhale small water droplets that contain Legionella bacteria. Occasionally, people can also get sick by aspiration of drinking water (such as during showering) containing Legionella bacteria.

Outbreak graphic


Legionella bacteria can be found in localized water sources, including in hot tubs, pools, hot water tanks, and cooling towers. But legionella bacteria can also originate from a public water system, entering and then colonizing in individual buildings, like nursing homes or hospitals. Water systems treat their water with disinfectants—like chlorine—to ensure that bacteria like Legionella does not grow in the water system and spread. But occasionally, changes to a water system’s disinfection treatment process can cause the bacteria to proliferate in the system, or at certain points within a system, such as “dead ends” or other areas where water can sit for long periods of time, or where chlorine residual levels are low or nonexistent.

Is there a connection to Newark’s drinking water-related violations?

There is not enough publicly available information to determine whether the recent Legionnaire’s disease outbreaks could be related to Newark’s drinking water system. However, Newark’s violation history makes clear that its system is not well operated or maintained and needs significant infrastructure updates and upgrades. In recent years, the state environmental agency has repeatedly cited Newark for its violations of the law designed to ensure that residents have access to safe drinking water:

  • Since June 2017, Newark has received four notices of non-compliance for its various violations of the federal Lead and Copper Rule. Newark is reporting a fifth exceedance in the most recent monitoring period, ending in June 2019, and we anticipate they will receive a fifth notice of non-compliance. These violations have lead to extremely high levels of lead in drinking water.
  • In December 2018 and January 2019, Newark received notices of violation for its violations of the Interim Enhanced Surface Water Treatment Rule, which is designed to ensure that turbidity (cloudiness) in drinking water does not exceed federal thresholds. Excessive turbidity in finished water is an indicator that a treatment plant’s filters are not operating properly and could be allowing bacteria or other pathogens to pass through treatment; this cloudiness also can interfere with the effectiveness of disinfection.
  • In 2015, 2016, and most recently in October of 2018 and January and March of 2019, Newark received notices of violation for exceeding maximum levels of disinfection by-products, including Total Trihalomethanes (TTHMs) or Haloacetic Acids (HAA5).

In particular, Newark’s reoccurring disinfection byproducts violations signal that the water system’s disinfection process is not working as it should. The disinfection byproduct chemicals found in excess levels in Newark’s water are linked to cancerand may also be linked to reproductive problems. According to the CDC, Legionnaires’ disease is known to be associated with changes in disinfection treatment. Water systems that experience disinfection byproducts exceedances, like Newark’s system, may ramp back chlorine dosing to abate excess disinfection byproducts; doing so can help to create an environment for the proliferation of legionella bacteria.

Researchers have found that the Legionnaires’ disease outbreak that killed 12 people and sickened at least 87 in Flint, Michigan, in 2014 and 2015 was linked to low chlorine levels in the municipal water system. Other studies have concluded that inadequate corrosion control treatment, combined with failure to maintain chlorine residual, can help to create the environment for Legionella growth. Unfortunately, Newark’s own consultants have found that the city’s corrosion control treatment is inadequate, raising questions about whether this could be encouraging growth of microbes in the distribution system, particularly if its chlorine residual levels have been inadequate in parts of its system. This question deserves an aggressive state and CDC (and perhaps another independent) investigation.

What are the next steps?

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Do other municipalities receive water from Newark?

Union County—where the recent deadly Legionnaires’ disease outbreak was reported—receives water from New Jersey American Water-Raritan, which purchase some water from Newark. According to news outlets, State health officials have stated that the Union County outbreak “does not appear to be associated with a single location exposure” and seems “spread throughout the county and is affecting a larger number of people.”

New Jersey American Water-Raritan also sells water to New Jersey American Water-Short Hills, which supplies water to West Orange. As noted above, West Orange had a serious Legionella bacteria outbreak last year.

Newark also sells some water to a number of other water suppliers, including New Jersey American-Liberty. And suppliers like Suez New Jersey Rahway, which occasionally purchases water from New Jersey American Raritan, may receive Newark water indirectly from other water suppliers. These suppliers may be using booster chlorination or other additional treatment before pumping Newark water into their system, but it is not clear that they’re doing so from publicly available information.

News outlets have reported that State health officials are in the process of conducting epidemiological and environmental testing about the Newark and Union County Legionnaires outbreaks. And Newark has confirmed that Legionella bacteria was present in the water supply at the senior home in Newark where at least three residents fell ill.

EPI curve example


However, Legionnaires’ disease outbreaks can take months or longer to uncover, especially if officials are not taking an aggressive approach to identifying the source. According to the CDC, potable water outbreaks are particularly difficult to identify, as compared to a localized outbreak at an individual building.

In addition to conducting building-specific tests, Newark and State officials should review existing chlorine data, conduct additional chlorine sampling, and test for Legionella bacteria, across Newark’s water distribution system, particularly in all areas where vulnerable people live, like homes for the elderly or hospitals.

July 10, 2019

Originally on NRDC.org


ERIK D. OLSON: Senior Director, Health and Food, Healthy People & Thriving Communities Program