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Addressing Stagnant Water in Buildings Due to COVID-19 Shutdowns
Wash, Clean and Disinfect are the most common terms you encounter nowadays as the COVID-19 pandemic has given us a new perspective on how important that we maintain our areas from disease break-outs. In our HVAC system, closed-areas should help clean and disinfect the air of office buildings, hotels, hospitals, schools, and more. But one thing we need to understand is, in all these activities--water is an essential part of the process.
NCH Chem-Aqua specializes in water treatment for decades and we have been critical about the presence of any bacteria and viruses in the recirculating water. While not new in the world of water treatment, cleaning and disinfecting of cooling water has been always the bloodline for Chem-Aqua water treatment specialists. Now more than ever, we have to be critical about building water systems. Due to lockdowns and limited operations, what normally have hundreds or thousands of gallons of water flowing through the fixtures, piping, and equipment daily may be stagnant for an unknown period of time, maybe several months.
Stagnation can lead to serious problems that cause long-term damage, reduce property values, and be very difficult to mitigate once the building is reoccupied. What are the problems caused by water system stagnation, and what can building owners do to combat them?
Low flow and stagnation in water systems deplete disinfectant levels and stabilizes temperatures to ambient. This provides ideal conditions for biofilms to form in hot and cold water storage tanks, hot water heaters, showerheads, faucets, ice machines, swimming pools, hot tubs, decorative fountains, and cooling tower systems. Biofilms are communities of surface-attached bacteria that are directly linked to serious corrosion problems, biofouling, and the growth of Legionella and other premise plumbing pathogens. Once established, biofilms are difficult to remove from water systems even with high disinfectant levels.
Although each situation is different, there are practical steps you can take when shutting down a building to help reduce the potential for water system damage and waterborne pathogen growth:
1. Keep the building HVAC systems live to maintain temperature and humidity control.
2. If not required for HVAC system operation, the cooling tower, chillers, heat exchangers, and associated piping should be completely drained. Leaving the system filled with stagnant water can result in severe corrosion, biofouling problems, and contribute to the transmission of Legionnaire’s disease.
3. If the cooling tower is required for HVAC system operation, specific treatment protocols may be required to help address low load conditions. Inhibitor requirements may need to be adjusted, and microbiological control can be more challenging. Do not discontinue water treatment if the tower is being operated.
4. Drain decorative fountains, hot tubs, and pools completely unless approved treatment and monitoring protocols are maintained. A Legionnaires’ disease outbreak in 2019 that resulted in over 140 cases and 3 deaths was linked to a poorly maintained hot tub display.
5. Disconnect the water supply to ice machines, coffee makers, water filters, and similar devices.
6. Disinfect inlet lines and install new filters prior to start up.
7. Keep water heaters set at their designated temperature (ideally at or above 120⁰F).
8. Flush all hot and cold water fixtures (showers, faucets, eyewash stations) at least weekly.
9. Document the flushing schedule with log sheets. Routine flushing may mitigate the necessity of disinfecting the potable water system before the building is reoccupied.
10. Periodically monitor the chlorine level at the point of entry and locations throughout the building to ensure flushing provides adequate residuals. Simple test kits are available for chlorine testing.
For more information, contact NCH Chem-Aqua.