An unintended workplace health threat resulting from the fight against COVID-19 could be lurking in an employer’s water system—Legionella, the bacteria that causes Legionnaires’ disease. As state and local governments begin lifting safe-at-home orders, employers and building owners will be restarting operations and reopening buildings (or parts of buildings) that may have been unoccupied for weeks. Many such operations include water supply systems that have also been shut down during the business closings. These dormant water systems and devices can lead to an increased exposure to Legionella for several reasons, including a lack of water circulation and a temporary cessation of water treatment and water quality monitoring programs. In anticipation of the large number of workplaces and other buildings that will be reopening in the near future, the U.S. Centers for Disease Control and Prevention (CDC) recently updated its guidance for reducing Legionella risks in building water systems.

Legionnaires’ disease is a severe form of pneumonia. Symptoms include cough, shortness of breath, high fever, muscle pains, and headaches. A common cause of Legionnaires’ disease is the inhalation of small droplets of contaminated water. Water that has been stagnant can lead to “conditions that increase the risk for growth and spread of Legionella” and other bacteria. According to the guidance, “[w]hen water is stagnant, hot water temperatures can decrease to the Legionella growth range (77–108°F, 25–42°C).” In addition, stagnant water can “lead to low or undetectable levels of disinfectant, such as chlorine,” normally found within a water system.

Employees can be exposed to Legionella from any number of water sources in the workplace, including:

• Lavatories and shower facilities that have been temporarily dormant;

• Infrequently used water safety systems, such as eye wash stations and safety showers;

• Cooling towers;

• Evaporative condensers;

• Hot water systems;

• Decorative water features or fountains;

• Hot tubs and spas;

• Various misters (such as cooling misters to reduce heat stress); or

• Industrial applications that create water mists.

The CDC recommends that building owners and managers take the following steps before restarting a dormant water system:

1. Evaluate the building’s water systems and devices and develop a water management program, if necessary. The CDC has developed a Water Management Toolkit to assist building owners and employers in evaluating the water systems and devices in their buildings to determine if they need a water management program and to help them develop an effective water management program.

2. Ensure any water heaters are set to at least 120⁰ F.

3. Flush the building’s water system.

4. “Clean all decorative water features, such as fountains.”

5. “Ensure hot tubs/spas are safe for use.”

6. “Ensure cooling towers are clean and well-maintained.”

7. “Ensure safety equipment including fire sprinkler systems, eye wash stations, and safety showers are clean and well-maintained.”

8. Maintain the water system (including “regularly checking water quality parameters such as temperature, pH, and disinfectant levels”).

The federal Occupational Safety and Health Administration (OSHA) also maintains detailed information on Legionella hazard recognition, control, and prevention on its website. Currently, OSHA does not have a specific standard for hazards associated with Legionella exposure. Rather, OSHA addresses Legionella hazards through the General Duty Clause, which requires employers to furnish each employee with a place of employment that is “free from recognized hazards that are causing or are likely to cause death or serious physical harm.”

If an employer has a water system that has been dormant for a significant time frame (due to compliance with state or local COVID-19 safe-at-home orders), the employer may want to consider identifying and assessing potential sources of Legionella risk prior to reopening the facility and developing a program to prevent and control any identified risks that may be present due to the bacteria.