Several days after the state of New Jersey announced a takeover by the Department of Environmental Protection, the state had more bad news for Trenton Water Works.

Legionella bacteria

Legionella—the bacteria that causes Legionnaires’ disease — a type of pneumonia that people can get after breathing in aerosolized water containing the bacteria.

The N.J. Department of Health announced the presence of Legionella—the bacteria that causes Legionnaires’ disease—in water samples collected from more than half of 30 homes served by TWW. This included homes from Trenton, Ewing and parts of Lawrence and Hopewell townships.

The Health Department’s testing was conducted in September after Legionella had been found in several homes that were voluntarily tested within the Hamilton Township area served by TWW in July.

The homes tested in Hamilton Township were part of an ongoing investigation to determine potential causes of Legionnaires’ disease previously detected in Hamilton Township, with five cases including one death reported since December 2021. The most recent case was reported to the Health Department in September 2022.

After the Hamilton cases, health officials tested the additional 30 homes in the TWW service area outside of Hamilton. The Department of Health did not report the exact number of homes where the bacteria was found.

Legionnaires’ disease is a type of pneumonia that people can get after breathing in aerosolized water containing the Legionella bacteria. People cannot get Legionnaires’ disease by drinking water that has Legionella. Though uncommon, people can get sick when water containing Legionella is aspirated into the lungs while drinking.

It is not known if individuals with Legionella detected in their homes are more likely to develop Legionnaires’ disease.

“While it remains rare for a healthy person who is exposed to Legionella to become sick with Legionnaires’ disease, people who are 50 years or older, especially those who smoke, or those with certain medical conditions, including weakened immune systems, chronic lung disease or other chronic health conditions, are at increased risk,” stated the Department of Health’s announcement.

Symptoms of Legionnaires’ disease include cough, shortness of breath, fever, muscle aches and headaches, which are similar to symptoms caused by other respiratory infections, including COVID-19.

Legionnaires’ disease can be fatal but is treatable with antibiotics. It is important for anyone who thinks they have symptoms of Legionnaires’ disease to contact their health care provider and seek medical evaluation immediately.

The Department of health said it continues to partner with the DEP and TWW to investigate factors that may be promoting the growth of Legionella bacteria and to evaluate remedial actions that can be taken to reduce Legionella in the system.

Courtney Peters-Manning, the mayor of Hopewell Township, said that the Legionella test results underscore that more needs to be done at TWW.

“While DEP’s actions last month are a good first step to fix immediate operational problems, longer term financial issues remain a concern, and the Trenton City Council in the past has voted down important investments in the utility.” she said. “Legislative action needs to ensure that the safe drinking water of 225,000 people is not held hostage by how the political winds blow in Trenton.”

“I look forward to working with our legislative representatives and surrounding cities and towns to ensure that these changes become reality,” she said. “We will not rest until this is accomplished.”

How to Decrease Risks of Legionella Exposure

According to N.J. Department of Health website, individuals, particularly those at high risk, can follow recommended steps to decrease the risk of Legionella exposure and best practices to limit the growth of Legionella in household water systems and devices (for the full list, go to

Avoid high-risk activities. If you are at an increased risk for Legionnaires’ disease, consider avoiding hot tubs, decorative fountains, power washing, or similar activities, which may generate increased amounts of aerosols or mist. A conversation with your health care provider may help you assess your individual level of risk based on underlying health conditions and co-morbidities. Your health care provider may recommend that you consider installing specialty biological 0.2-micron filters on your showerhead if you are severely immunocompromised and receive water from Trenton Water Works.

Maintain in-home medical equipment. If using medical equipment that requires water for use or cleaning such as non-steam generating humidifiers, CPAP or BiPAP machines, nasal irrigation devices such as Neti Pots, and attachments for nebulizers, follow manufacturer’s instructions for use and maintenance. This often includes using sterile water instead of tap water in the device.

Clean and/or replace your showerheads and faucet aerators (screens) per manufacturer’s instructions whenever buildup is visible. This is particularly important if you haven’t cleaned your showerheads or faucet aerators recently. Cleaning might require you to remove the showerhead and hose and soak in a solution (such as white vinegar or a bleach solution) to remove buildup. If using chemicals, follow instructions found on the back of the bottle for safe use.

Keep your water heater set to a minimum of 120 degrees F. This temperature will reduce Legionella growth and avoid potential for scalding (hot water burns). Setting the heater to a higher temperature may better control Legionella growth, especially if you have household members at increased risk for Legionnaires’ disease. 

Thoroughly flush the water at each tap (e.g., sink, showerhead) for 20 minutes after cleaning showerheads and faucet aerators and increasing the temperature of the water heater,Try to minimize exposure to splashing and mist generation, for example, by leaving the room while the water is running.

Conduct routine flushing. Sinks and shower taps that are not used often can increase the risk of Legionella growth in other areas of the home. Let your faucets and showers run for at least three minutes when they have been out of use for more than a week. Minimize exposure to splashing and mist generation, for example, by leaving the room while the water is running. Additionally, you may consider flushing your water following any water disruption to your home, such as low pressure or discoloration, resulting from a water main break or nearby hydrant flushing.

Follow manufacturer’s instructions for maintaining your water heater and expansion tank, including periodic flushing, draining, and removal of sediment. If manufacturer’s instructions are unavailable, seek advice from a licensed professional.

Clean and/or replace all water filters per manufacturer’s instructions. All whole-house (e.g., water softeners) and point-of-use filters (e.g., built-in refrigerator filters) must be properly maintained.

Drain garden hoses and winterize hose bibsDetach and drain the hose, shut the water valve off inside the home, and drain the pipe when not in use for the season.

Follow manufacturer’s instructions for maintaining your hot tub. Ensure disinfectant levels (e.g., chlorine) and maintenance activities (e.g., cleaning, scrubbing, replacing the filter and water) are followed. For more information, be sure to review CDC’s recommendations for residential hot tub owners.

Operate and maintain your indoor and outdoor decorative fountains according to manufacturer’s instructions to limit your exposure to Legionella. Household members at increased risk for Legionnaires’ disease should avoid exposure to decorative fountains. If manufacturer’s instructions for cleaning and maintenance are not available, minimum cleaning frequency recommendations can be found in CDC’s Legionella Control Toolkit.

Remove, shorten, or regularly flush existing dead legs. Plumbing renovations can lead to the creation of dead legs, a section of capped pipe that contains water but has no flow (or is infrequently used). For future renovations, ensure your plumber avoids creating dead legs.

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