COVID-19 and Water Management

Environmental Safety Technologies (EST) would like to take this time to discuss with all of our water treatment and hospital partners about the impact COVID-19 can have on water systems, both cooling towers, and potable water systems.

Green Cooling Tower by
During this time of the Coronavirus outbreak, we have heard from many of our hospital partners that they are shutting down units and sometimes entire floors as elective surgeries and non-critical procedures are being postponed preparing for COVID-19 victims. This has led to some hospitals having laid off staff to separate them from the campus and reduce the possibility of exposure. While these are necessary steps in many institutions, it leaves open the possibility of allowing water to stagnate in piping and decreases the use of cooling towers, which may already be in low demand due to moderate temperatures.
A recent rapid response study at the University of Purdue and a team of industry experts discussed the possibility of Legionella amplification and increased risk of Legionnaires disease in buildings with low or limited water usage during the current COVID-19 Response. That study and its recommendations can be found at this link
The following articles have discussed the importance of maintaining low-use water systems during this unprecedented time.
It is therefore important to keep showers, faucets, toilets, and other water outlets flushed on a regular basis during these periods of limited use. Most organizations, including EST, follow the recommendations of ASHRAE Guideline 12-2020, and the CDC ( in recommending the flushing be done every three days, or on a twice-weekly basis. ASHRAE Guideline 12-2020 also further addresses Cooling Towers, stating that when a cooling tower system is to be shut down for three or more days, the entire system (cooling tower, system piping, heat exchangers, etc.) should ideally be drained to waste. If draining the system is not practical for shutdowns of short duration, then circulate biocide once or twice a week in the offline tower to achieve a residual and use the ASHRAE startup procedures for undrained towers. (Consult with your water treatment service provider to determine the frequency and duration of disinfection)
For potable water systems follow the building’s Legionella Water Management Plan (WMP) regarding shutdowns or for facilities without a WMP the following recommendations would be prudent if that facility has not had additional biocides or frequent flushing during this time of limited use.
    • Collect first draw water samples to evaluate the residual chlorine available at the water source and multiple points, including the furthest point in the building.
    • If these samples indicate a reduction in residual chlorine or water discoloration or odor, a building flush should be implemented to reduce the risk of Legionaries disease.
    • Follow the recommendations of your water treatment vendor or your local municipality to perform a thorough flush of your facility.
    • Reevaluate the residual chlorine and water condition (discoloration, odor, etc.)
    • Collect bulk water samples (for Legionella analyses) from distal fixtures to validate the effectiveness of the procedure.
For starting up Cooling Tower systems that have been drained, follow the water treatment vendor recommendations, while also considering these ASHRAE guidelines:
  • Clean all debris (e.g., leaves and dirt) from the cooling tower.
  • Fill the system with water. While operating the condensing water pump(s)—and prior to operating the cooling tower fans—bring the system under good biological control by either method below.
  • Maintaining the maximum recommended residual for the biocide used prior to shut down for a sufficient period of time.
  • Adding sodium hypochlorite to achieve 4-5 ppm free chlorine residual at a pH of 7.0 to 7.6, held for six hours.
  • After step 2 has been successfully completed, the fan can be turned on, and the system returned to service.
Maintenance of your water systems in accordance with your water management plan and ASHRAE guidelines will help us all ensure that we don’t enter an increased period Legionella outbreaks as we return to regular activity following this Coronavirus Pandemic.

Get in touch