Recommendations for Water Supply Flushing for Reopening of Buildings
Under Statewide COVID-19 Transition Plan, buildings re-opening that have had little to no water usage during the stay-at-home order due to the COVID-19 pandemic, it is important to flush water that has been stagnant in both cold- and hot-water distribution lines and fixtures. Low water usage can contribute to bacterial growth, including Legionella which can cause a serious type of pneumonia called Legionnaires’ disease. It also can also cause other water quality issues with potential health risks due to build-up of lead and copper in stagnant water that’s been collecting in older pipes and fixtures.
Devices that store water, such as drinking water fountains, water heaters, storage tanks, and any droplet or mist-forming devices such as cooling towers, humidifiers, shower heads, and certain medical and manufacturing devices and process equipment should also be flushed and disinfected in accordance with manufacturer’s recommendations or industry best practices.
Please note that this guidance applies to the water systems of all types of buildings that are unoccupied or partially occupied during the COVID-19 pandemic, including but not limited to office buildings, manufacturing facilities, medical offices (e.g., physician and dentist offices, ambulatory surgery centers, outpatient centers, etc.), government facilities, and religious institutions. If you are a tenant of a building, we recommend that you share this information with the building owner, building manager, or management company and ask them to consider taking these precautions.
For full recommendations refer to the following two documents:
Legionnaires' Disease in Ohio
Reports of Legionnaires’ disease in Ohio are increasing annually, with approximately 600 cases reported in 2015. Legionella are bacteria that grow naturally in the environment and especially in warm water. It occurs in freshwater lakes and streams, however, the quantities in natural water bodies are generally insufficient to cause disease. Growth of Legionella can occur in building water systems where exposure to aerosols containing the bacteria can cause disease.
Growth or amplification of Legionella can occur under different environmental conditions in water systems. Conditions that promote amplification include:
- Water stagnation
- Warm temperatures (25 - 51° C [77° - 124° F])
- Presence of scale and sediment
- Presence of organic matter (biofilms)
- Presence of protozoa in the water
- Lack of residual disinfectant
The bacteria grow well in warm water (25 - 51° C [77° - 124° F]) and in the presence of biofilms or organic material. In building water systems, it is likely to be found when there are low levels of disinfectants (ex. Chlorine), after construction, dead ends in the piping, stagnant water, in cooling towers, thermostatic mixing valves, decorative fountains, ice machines.
Legionella is dispersed through aerosolization of water droplets containing the bacteria. Sources of aerosolized water droplets include:
- Showers and faucets
- Cooling towers
- Hot tubs
- Decorative fountains
- Large, complex water systems
If a person inhales water droplets or mist containing the bacteria, they may get an infection. An infection of the lungs causing pneumonia is called Legionnaires’ disease, and a milder infection of the upper respiratory tract is called Pontiac Fever.
Building owners and managers can take action to reduce the risk of Legionella growth in water systems and cooling towers. Click on the navigation links to the left or visit the CDC Legionella website for more information and technical resources: https://www.cdc.gov/legionella/index.html