Skip to main content

Legionella Exposures and the Workplace

By Jason Jantzi, Risk Management Consultant – Fire | 503-559-0389 or 800-285-5461



Extended building closures can increase the risk for Legionella bacteria to grow in water systems.  This can pose a significant risk to our health in a time we are already concerned with COVID-19. Although the bacteria that causes Legionella occurs in natural water sources, outbreaks are generally caused by the increased growth of the bacteria from within manmade water systems.


What is Legionella? According to the Mayo Clinic, Legionella bacteria can cause Legionnaires’ disease, a severe form of pneumonia (lung inflammation usually caused by infection). Most people catch Legionnaires' disease by inhaling the bacteria from water or soil. Older adults, smokers and people with weakened immune systems are particularly susceptible to Legionnaires' disease.


Many districts do not have a formal management plan for their buildings, and this pandemic has caused extended discontinued use of the water systems that may increase the risk of stagnant water remaining in the plumbing for several weeks or months. Stagnant water from plumbing lines can become aerosolized and generate a mist when released through shower heads, faucets, and garden fixtures. This mist can be inhaled, allowing the bacteria that causes Legionella to enter your lungs and potentially cause an infection.


There can be an increased risk for growth of bacteria in water inside equipment such as cooling towers, fountains, water pipes, and humidifiers. There are simple measures that all districts should take to reduce this risk.



Identify all water sources and fixtures.

  • Drain and disinfect indoor water features and fountains.
  • Drain water from all process equipment dishwashers, floor cleaners, tools, and medical equipment. Water heaters should be drained and disconnected if not in service.
  • Assign a team to inspect the building on a weekly basis, at least.
  • Pre-treat boilers and water-cooling towers, as necessary.


During the Closure

  • Inspect the entire building for water leaks or broken fixtures.
  • Run hot and cold water from each fixture (e.g., shower heads, sinks, hoses, spray hoses, exterior hose bibs) for 5 to 7 minutes each week.
  • Continue to inspect emergency eyewash and shower stations by running them every week.
  • Inspect outdoor fixtures and other areas that can accumulate stagnant water.
  • Maintain climate control systems.
  • Maintain pool and spa equipment chemistry at normal levels.
  • Flush all toilets weekly.
  • Maintain water heaters at 140° F.
  • Add water to custodial drains or sinks not in active use to avoid sewer gas leakage


Upon Returning to the Workplace

  • Inspect, clean, and disinfect all water features and fountains.
  • Inspect, clean, and disinfect water cooling towers.
  • Defrost, drain, sanitize, and replace the filters on commercial ice machines.
  • Confirm proper chlorination of pools and spas.
  • Inspect all equipment that has water tanks for development of a biofilm and disinfect, as necessary.
  • Clean or replace water faucet filters and replace any water filters on sinks


SDAO has put together a COVID-19 Reopening Toolbox for your use when reopening your office(s) during the COVID-19 pandemic. To view these helpful resources, please visit our website.


CDC Toolkit: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings