Sleeping giants: Awakening building water systems

I’m one of the lucky people who was able to transition from working in an office to a remote setting, doing what’s advised to keep myself and my community healthy. Eventually (and hopefully!), I’ll get back to the office, to a building that’s likely been mostly unoccupied for some time. Will our offices – everyone’s offices – be safe for reentry when the time comes? While there has been plenty of discussion about the measures needed to minimize spread of COVID-19, buildings affect human health in several other ways that can’t be overlooked. As we look to reopen our buildings, we should also think about ways to minimize risk of other diseases through proper building operations and policies.

Buildings aren’t meant to be left dormant. Just like humans, their systems are designed to follow certain rhythms and patterns in order to stay healthy. HVAC devices, networks of pipes and ducts conveying water, sewage and air, plus extensive networks of wires and electronics bring life to buildings as long as they’re adequately used and maintained, and they must be given extra care when they’re asleep for long periods of time. Because of the speed at which the pandemic spread, some of these systems need additional oversight before bringing a building back online.

It’s a matter of time

Because of the documented potential of the SARS-CoV2 virus to survive on air and create fomites (i.e., contaminated surfaces), much of the public health discussion has been focused on ventilation and air treatment systems. ASHRAE and REHVA—organizations that dictate standards related to these topics—are providing and updating guidelines on best practices for re-entering offices and buildings as the science rapidly continues to evolve. However, let’s not forget about other building components that should be addressed, including those where water is involved. Water is to a building what blood is to the human body, and as it circulates it can become an agent of disease to its supporting infrastructure. It can even spread actual diseases to building occupants if left inside pipes and devices for extended periods of time. Inside buildings, the water age is the time passed between when water enters the building and when it is used. Letting water get old can have serious repercussions due to chemical and biological factors.

Because drinking water pipes are never sterile, municipalities add disinfectant to water to prevent pathogens’ spread. The disinfectant – usually chlorine - travels with the water, preventing microbial growth from the treatment plant to the user. Because of reactions with pipe materials, other chemicals, natural organic matter and microorganisms, chlorine concentration in water decays with time. If the water becomes too old, all chlorine may decay, potentially allowing pockets of bacteria attached inside pipes and fixtures (biofilms) to grow. There’s solid evidence that water age increases the diversity and concentration of bacteria in drinking water pipes and raises the potential for some waterborne pathogens to develop.^1,2 In addition, stagnation of hot water with no disinfectant inside fixtures and pipes may create a niche for Legionella, the bacteria responsible for Legionnaires’ disease and Pontiac fever.³

The dirty secrets of stagnation

Corrosion also adds to the impacts of stagnation on water microbiology. Drinking water utilities add corrosion control agents (typically silicates or phosphates) that attach to pipes and create protective scales,⁴ a critical step for when pipes or solder contain lead like in many older buildings. Without delving much into the chemistry, stagnant water allows for micro-environment creation on pipe surfaces that can dissolve metal constituents and cause localized pits to develop.⁵ Chemical and microbiological effects of water stagnation often appear together, so it’s important to address water stagnation, particularly in buildings with extensive pipe networks, to help prevent the development of clusters for pathogens and to protect the integrity of water pipes, fixtures and assets such as spa pools and cooling towers.

Questions about how to prevent water stagnation aren’t new. These issues occur seasonally in schools, hotels and commissioned, unoccupied buildings. Similarly, many existing cooling towers used to provide comfort cooling in hot seasons are shut down for the winter. But because of the unexpected and forced vacancy of many office buildings due to COVID-19, these questions are being considered on a much larger scale. Health departments, trade organizations, research groups and water consultants are bringing the issue to the forefront. The appropriate response depends on many factors, including the size, complexity and age of the building’s pipe system, how water is heated and distributed, and the presence of other water assets that recirculate water such as cooling towers, spas or decorative fountains.⁴ The degree of maintenance that was exerted prior to this pandemic is also a key factor. That said, building managers can take several specific actions during and after the closures to support healthier building reentry:

• Keep it hot (or cold). If building maintenance was scheduled during its closure, and the expectation is to bring the building back to functioning in a relatively fast manner, continuing the operation of any building-wide hot water loops including heaters and pumps, is key.⁴ Legionella grows at temperatures within 25 and 50 Celsius (70-120 degrees F), so keeping hot water hot is essential for preventing Legionella spread. Periodic flushing of hot water faucets, avoiding full open valves that may disperse aerosols,⁶ flushing cold water taps to keep cold water cold (below 25 degrees Celsius) and to ensure that fresh, disinfectant-containing water is used, is also recommended.⁶
• Inspect. In unoccupied buildings where water has been stagnant for weeks or months, a thorough inspection of the components of the cold and hot water systems should be performed to assess the systems’ integrity and ability to deliver water.⁴ Corrosion may have compromised parts of these systems. Pipes, insulation, pumps, filters, valves, heaters and backflow preventers should be inspected.
• Flush the lines. The U.S. Centers of Disease Control and Prevention (CDC) recommends a building-wide flushing of the cold and hot water lines.⁷ This process intends to bring in fresh water and to scrub patches of biofilm that may have formed in the pipes using the water pressure. However, building flushing needs must be carefully planned and executed to help fresh water to reach all sections of the building and to prevent the loss of water pressure in certain sections of the pipe network. Respiratory protection equipment is required for those performing flushing to prevent the inhalation of water aerosols potentially containing Legionella.⁸ Aerators, showerheads and filters must be removed in advance and cleaned or replaced.⁷
• Consult the professionals. Depending on the maintenance of the building during shutdown, whether the hot water loops were in operation, the complexity of the pipe network and the type of occupants (e.g., those deemed higher risk such as immunocompromised people), additional remediation strategies may be needed. Consult your local health departments, building engineers and water professionals to evaluate the most appropriate strategy on a site-by-site basis.
• Monitor parameters. Prior to re-entry, monitoring disinfectants (chlorine or chloramine) and hot water temperature (taken before mixing with cold water in faucets, as anti-scalding devices may be present) can be used to guide flushing decisions.⁸ Lead and/or copper testing may also be advisable to verify the effectiveness of remediation actions.
• Drain and clean assets. Apart from building-wide hot water systems, all other assets that contain recirculated water loops, including decorative fountains, spa pools and cooling towers, need to be assessed for Legionella.⁴ Any standing water inside these devices must be drained. Surfaces in contact with water must be inspected, cleaned and sanitized following manufacturer and health department directions. It’s common to perform a system disinfection before resuming service. Verifying the water treatment systems’ functionality, monitoring chemical levels and updating maintenance records is vital to minimize potential exposure to aerosolized Legionella.⁷
• Show your work. Documenting all monitoring results and actions performed to maintain water quality is key to evaluate the building’s water systems and for determining spots that require additional repair or upgrade.⁹

Overall, water needs to flow through the building’s veins as much as possible, without biofilm clogging. Establishing a plan to manage water assets, address water stagnation and follow recommendations from water specialists and health departments is a proactive approach employers, building owners and managers can take to help protect their buildings and their occupants from diseases beyond COVID-19.

In the meantime, let’s not forget to thank the building maintenance staff who work to ensure all vital functions of our buildings remain working, allowing those of us at home to return to work knowing our buildings will be awake and ready to support our health and well-being. Once building occupants have returned, remember that responsibly using water can maintain water quality and avoid stagnation. Actively maintaining water quality and communicating that commitment to building occupants can increase water quality confidence and decrease excess use of bottled water, instilling a virtuous circle of promoting sustainability through hydration. As we’ve learned from this pandemic, it’s everyone’s job to protect each other, our shared resources and our planet.

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Resources

[1] Ling F, Whitaker R, LeChevallier MW, Liu W-T. Drinking water microbiome assembly induced by water stagnation. The ISME Journal. 2018;12(6):1520-1531.

[2] Wang H, Masters S, Edwards MA, Falkinham JO, Pruden A. Effect of Disinfectant, Water Age, and Pipe Materials on Bacterial and Eukaryotic Community Structure in Drinking Water Biofilm. Environmental Science & Technology. 2014;48(3):1426-1435.

[3] US Centers for Disease Control & Prevention. Legionella (Legionnaires’ Disease and Pontiac Fever). https://www.cdc.gov/legionella/index.html. Published 2019. Updated April 30, 2018. Accessed December 20, 2019.

[4] Proctor C, Rhoads W, Keane T, et al. Considerations for Large Building Water Quality after Extended Stagnation. OSF Preprints. 2020. (Great recent critical review of strategies for addressing water stagnation)

[5] Masters S, Wang H, Pruden A, Edwards MA. Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology. Water Research. 2015;68:140-149.

[6] ESCMID Study Group for Legionella Infections (ESGLI). ESGLI Guidance for managing Legionella in building water systems during the COVID-19 pandemic. 2020

[7] US Centers for Disease Control and Prevention (US CDC), Guidance for Reopening Buildings After Prolonged Shutdown or Reduced Operation, 2020

[8] Washington State Department of Health (WA DOH). COVID-19 Guidance for Legionella and Building Water System Closures. 2020

[9] World Health Organization (WHO). Water Safety in Buildings. Geneva, 2011. (Fundamentals for water safety plans in buildings)

Further recommended reading

Center for Plumbing Safety, Purdue University. Restoring Water to Medical, Residential, and Commercial Buildings, Shutdowns, Unsafe Water. 2020 (A list of resources and FAQs to guide building-wide responses to re-occupation)

European Guidelines Working Group. European Technical Guidelines for the Prevention, Control, and Investigation, of Infections Caused by Legionella Species. 2017 (Good document to establish Legionella management plans)

US Environmental Protection Agency (US EPA), Information on Maintaining or Restoring Water Quality in Buildings with Low or No Use, 2020