The flow of tap water through building water systems, under normal conditions, prevents the buildup of bacteria and metals in pipes, and hot water tanks. However, the threat of the deadly coronavirus disease (COVID-19) has caused the temporary shutdown or reduced operation of a building and reduction in normal water use which resulted in the breeding of bacteria in stagnant water.
According to the Centers for Disease Control and Prevention (CDC), two potential microbial hazards that should be considered prior to re-opening after a period of building inactivity are mold and Legionella (the cause of Legionnaires’ disease). Mold appears after a “prolonged period” which may be days, weeks, or months depending upon building-specific factors, season, and weather variables. Legionella, on the other hand, may take weeks or months depending on plumbing-specific factors, disinfectant residuals, water heater temperature set points, water usage patterns, and preexisting Legionella colonization.
Apart from mold and Legionella, additional hazards may exist for returning occupants such as non-tuberculous mycobacteria, changes in water chemistry that lead to corrosion, leaching of metals (such as lead) into stagnant water, disinfection by-products, and sewer gases that enter buildings through dry sanitary sewer drain taps.
Workplace health and safety
Apart from the emphasis on social distancing and enhanced cleaning, the CDC guidelines for Covid-19 has created recommendations that all employers can use to protect their workers and clients and to keep a safe and healthy workplace.
Check the building if it is ready for occupancy
Building employers, owners, managers, and operations specialists should ensure that the ventilation systems in their facility operate properly. For building heating, ventilation, and air conditioning (HVAC systems) that have been shut down or on the setback, the CDC guidelines for Covid-19 stated that they will have to review new construction start-up guidance provided in ASHRAE Standard 180-2018, Standard Practice for the Inspection and Maintenance of Commercial Building HVAC Systems.
Increase circulation of outdoor air as much as possible by opening windows and doors, using fans, and other methods. However, according to the CDC guidelines for Covid-19, windows and doors should not be opened if it poses a safety or health risk for current or subsequent occupants, including children. It may allow outdoor environmental contaminants including carbon monoxide, molds, or pollens into the building.
Evaluate the building and its mechanical and life safety systems to determine if the building is ready for occupancy. Building employers, owners, managers, and operations specialists should check hazards associated with prolonged facility shutdowns such as mold and Legionella, rodents or pests, or issues with stagnant water systems.
Minimize Mold Risk (both in the air and water)
In the CDC guidelines for Covid-19 on Reopening Buildings After Shutdown, the health protection agency suggested five steps to minimize mold risk during and after a prolonged shutdown, which includes:
– Maintain indoor humidity as low as possible, not exceeding 50 percent, as measured with a humidity meter.
– After a prolonged shutdown and before occupants return, buildings should be assessed for mold and excess moisture.
– Although rare, it is possible to have mold in the potable water system. Mold is a fungus that needs water, oxygen, and an organic food source to thrive and survive. The water supply system should be flushed and disinfected.
Chemstar WATER has state-of-the-art technologies to detect microbiological activity, such as adenosine triphosphate (ATP) monitors, proprietary quantitative polymerase chain reaction (qPCR) testing systems as well as partnering with reputable laboratories.
– After an assessment has confirmed that mold and moisture are not detected or after remediation has been completed, a building HVAC system that has not been active during a prolonged shutdown should be operated for at least 48 to 72 hours (known as a “flush out” period) before occupants return.
– After a building is reopened and occupied, routine checks of the HVAC system are recommended to ensure operating efficiency.
– If no routine HVAC operation and maintenance program are in place for the building, one should be developed and implemented.
Minimize Legionella Risk
The CDC guidelines for Covid-19 has recommended eight steps to minimize risk before the building reopens, which are:
1- Develop a comprehensive water management program (WMP) for the water system and all devices that use water.
2- Ensure the water heater is properly maintained and the temperature is correctly set.
3- Flush the 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, eyewash stations, and safety showers are clean and well-maintained.
8- Maintain the water system. Building employers, owners, managers, and operations specialists should consider contacting their local water utility to learn about any recent disruptions in the water supply.
After the water system has returned to normal, ensure that the risk of Legionella growth is minimized by regularly checking water quality parameters such as temperature, pH, and disinfectant levels.
Chemstar WATER recommends the robust water management program controlling microbiological activity, especially Legionella Pneumophila, through effective biofilm control in the cooling and potable water systems.
Keeping the workplace safe and healthy
Employers are responsible for providing their employees and clients a safe and healthy workplace. In the CDC guidelines for Covid-19, it’s stated that a thorough hazard assessment should be conducted in the workplace to identify potential workplace hazards that could increase risks for Covid-19 transmission. Work and common areas where employees could have close contact with others should also be identified. These areas include meeting rooms, break rooms, the cafeteria, locker rooms, check-in areas, waiting areas, and routes of entry and exit.
All employees in the workplace should be included in communication plans and if contractors are employed, communicate with the contracting company regarding modifications to work processes and requirements for the contractors to prevent transmission of Covid-19. The CDC guidelines for Covid-19 also states that employees and supervisors are to be educated on the steps they can take to protect themselves at work.
Cleaning and Disinfection
Reducing the risk of exposure to Covid-19 by cleaning and disinfection is an important part of reopening public spaces that will require careful planning. The spread of the virus can be slowed down by practicing social or physical distancing, frequent handwashing, and wearing face masks or face coverings. The virus that causes Covid-19 can be killed if the right products are used. According to the CDC guidelines for Covid-19, normal routine cleaning with soap and water will decrease how much of the virus is on surfaces and objects, which reduces the risk of exposure.
Disinfection using EPA-approved disinfectants against Covid-19 can also help reduce the risk. When EPA-approved disinfectants are not available, alternative disinfectants can be used such as 1/3 cup of bleach added to 1 gallon of water, or 70 percent alcohol solutions. The CDC continues to add their guidelines for Covid-19 to keep employers and the general public up to date on its website: https://www.cdc.gov/coronavirus/2019-ncov/