By Chris Boyd
Controlling the spread of COVID-19 requires the collective effort of physical distancing. Although this is imperative to save lives from the novel disease, many hotels, resorts, offices, and other buildings are now partially or entirely shut down. As a result, the water systems in these buildings are experiencing low to no flow, loss of disinfectant residual, tepid water temperatures, and other hazardous conditions that can increase Legionella amplification, which can cause Legionnaires disease.
To avoid a dramatic increase in Legionnaires disease, there are several actions that building owners should take now and prior to returning buildings to full service to reduce hazardous conditions caused by the COVID-19 low building-occupancy rates.
Water management programs need to be updated to reflect COVID-19 operating conditions
Now is the time to update your water management program, or create one, to reflect the impact of COVID-19 on your building. The plan should describe all water systems, the flow of water through those systems, how risks are managed, and, critically, who is taking responsibility for the actions called for in the water management program. The CDC recently issued COVID-19 guidance for building water systems, and step one is to update and/or develop your water management plan. The health and safety of your employees, tenants, and customers cannot be properly protected without a water management plan and program.
Stagnant water amplifies risks—keep the water moving
When buildings have low occupancy, the water age in these systems increases. Several hazards are associated with stagnant water and reduced flow rates within plumbing systems and equipment, such as biofilm growth, microbiological amplification (including Legionella bacteria), corrosion, and lead accumulation. Keeping the water flowing is the best practice to minimize risks caused by low or no occupancy. Developing a successful flushing program requires careful planning, and those implementing the plan should follow site-specific procedures for the parts of the building that have low or no consumption. The building owner will need to determine the volume of water that needs to be turned over for specific sections of the building, the locations where the flushing will occur, and the time needed to flush specific taps. An efficient flushing regimen will provide fresh water with an adequate disinfectant residual circulating in the water systems and will reduce the opportunities for biofilm grow within the plumbing system.
Disinfectant residual—control biological growth
Generally, incoming water from your utility contains a disinfectant residual that limits biological growth in distribution piping and your building. In buildings with low water utilization and stagnation as a result of COVID-19, the disinfectant residual will be lost and one of the critical barriers to bacteria amplifying removed. One of the goals of the flushing program is to bring fresh disinfectant residual into the building. As a first step, a building needs to measure the incoming disinfectant residual provided by its water utility. If the residual from the water service connection is low, the building should contact its water utility so it can take proper corrective actions. The building’s water management plan needs to be updated to identify the points and frequency that disinfectant residuals will be measured during COVID-19 operations. If the residual at distal points are too low, this may indicate high water age, high organic contamination, and/or heat gain in some parts of the system. If you cannot maintain a disinfectant residual, then corrective actions are needed.
Hot water systems—avoid accelerating the growth of Legionella
Low or no demand for hot water systems can create hazards from both stagnation and temperature ranges that accelerate the growth of Legionella. Legionella proliferates within 77°F–108°F. It is critical that building owners include in their water management plans steps to control temperatures in hot water storage units and hot water piping systems to prevent Legionella amplification. Temperatures need to be collected at strategic locations to evaluate if criteria established in the water management plan and by the local jurisdiction are within proper range.
Some water systems, such as cooling towers, decorative features, and pools, can be shut down temporarily; others must remain in operation. Those systems that are shut for an extended period should follow the shut-down and start-up procedures in the building’s water management plan. Systems that may be shut down intermittently, such as cooling towers used for comfort or process cooling, need to be carefully managed to ensure continued application of biocides and that water continues to be recirculated through the system so every drop sees every biocide feed. If a cooling tower system is not actively managing Legionella growth for five days, the system should be fully cleaned and disinfected. NSF’s protocol (NSF P453) for managing Legionella risks from cooling towers provides detailed guidance.
Drinking and emergency water storage
If present, drinking water storage tanks require special attention and should not be shut down. In a low-demand situation, water will age in the tanks which can result in biofilm formation, sediment deposits, and corrosion, depending on the materials in the tank. The goal should be to turn over the water in the tank at least every 72 hours (your tank’s operational capacity should be three times the current daily consumption). If possible, keep tanks at the lowest operational level, enough to renew water every 24 to 72 hours.
All emergency water systems should be kept in operation as usual (e.g., fire suppression). Even if risks seem to be lower because of low occupancy, all emergency systems must be ready in case of need. Recirculation pumps for hot or cold domestic water systems should be used to prevent stagnation.
Verification and validation—documenting standard of care and returning to normal operations
Emphasis should be placed on maintaining accurate and defensible records to verify the water management program has been implemented as designed. Records should be kept updated as they are your best ally when your building comes back to normal operation. Record any measures taken to keep water safe as you would during normal operation. Documentation should include the control measure or activity, its results, who was responsible, and the date it was performed.
Testing your water system is even more important during this change in operation and water demand. Continue water quality and Legionella testing as planned. Besides protecting yourself from potential litigation, it is beneficial to check if control measures during this time are effective at preventing Legionella growth.
Other measures specific for your building and water systems may be necessary, so evaluate your situation and update your water management program if needed. Control measures should be in practice to effectively minimize risks from waterborne diseases to protect public health and to keep water safe during temporary periods of low water demand in buildings.
About the author
Chris Boyd is general manager of Building Water Health at NSF Health Sciences LLC, a company of NSF International, a global public health organization.