Bringing Buildings Back On-line & Sanitizing Water Treatment Systems

Oct. 1, 2020

This article originally appeared in WQP October 2020 issue as "Life After Lockdown"

About the author:

Eric Yeggy is technical affairs director for the Water Quality Association. Yeggy can be reached at [email protected].

It has been a long, hard-fought battle. The water treatment industry has been working overtime to serve customer needs while observing health protocols and guidelines to ensure customer and employee safety.

But what about buildings that have been offline for many months? This is yet another phase of the COVID-19 crisis that water treatment professionals need to address. A variety of buildings and offices may be affected. Examples include restaurants, coffee shops small businesses and retail establishments. Let us not forget schools.

It is important to understand that there is no evidence that the COVID-19 virus has infected drinking water supplies. However, stagnant conditions can accelerate the growth of other pathogens or accelerate the growth of non-pathogenic microorganisms that lead to fouling, bad tastes or odors. The stagnant conditions can also cause corrosion to occur, putting unsafe levels of lead or other metals in the water, and increase the concentration of disinfection byproducts. These side effects of stagnation are not just occurring in the plumbing but could also be happening inside of treatment systems. 

Develop a Plan to Bring Treatment Systems Back Online

Water treatment professionals should engage with clients early in the process to begin planning how to bring treatment systems back online in a safe and sanitary manner. It is important to find out if the entire building has been vacant or if portions of it may still be occupied. Portions of the building that have been occupied were not subject to complete stagnation and had water flowing through those areas. These areas may have contained adequate flushing and disinfectant to prevent the buildup of microorganisms. All of these factors should be considered as plans are made to bring treatment systems back online.

The building owner may be working with other qualified professionals to establish a formal plan to bring all systems in the building online, including water and sewer services. State or local authorities should be consulted on recommissioning the building, as they may provide general guidance on any associated regulations. Local water utilities may also be able to assist with recommendations and may be willing to temporarily raise disinfectant levels to accommodate periods of high flushing.

Where possible, place all water treatment systems in bypass while the building plumbing systems are being flushed. Remember that the pipes are probably full of water that has been stagnant for a long period of time. Any residual disinfectant in the water likely disappeared quickly when the water became stagnant. The stagnant conditions and lack of disinfectant have created ideal conditions for growth of bacteria and other microorganisms. This stagnant water should not be drawn through a water treatment system. Doing so would flush the highly contaminated water through the device, making the job of sanitizing the treatment system much more difficult.

Work with the building owner and the other professionals who are conducting the flushing activities to encourage them to start by flushing the service line first (e.g., using outdoor spigots) then to flush the premise plumbing as much as possible using toilets, bathroom sinks and other taps that do not contain treatment devices. The bypass on any point-of-entry (POE) treatment equipment can be used to prevent it from being further contaminated by the initial flushing activities. Also, be aware that the drain traps in floor drains and sink basins may have dried out, leading to foul odors. These drains are a potential source of contamination that must be avoided working around as the water treatment systems are sanitized.

Service & Sanitize Treatment Systems

After freshwater flushing of the premise plumbing has been completed by the building owner or their professionals, the process of servicing and sanitizing the treatment systems can begin. Replaceable filter cartridges and other potentially spent or contaminated consumables should be changed out wherever possible. Membrane modules may have dried out and cracked or become fouled with bacterial growth. Do not forget to check ultraviolet (UV) systems to see if the lamp needs to be replaced, especially if the system has remained on the entire time with no flow. 

The Water Quality Association (WQA) recommends following the treatment system manufacturer’s instructions on sanitation if provided. If the manufacturer does not provide instructions on sanitation of their product, try contacting the manufacturer or its distributor directly and try checking with the disinfectant manufacturer. Many companies that sell disinfectants have begun issuing instructions on how their product can be used with water appliances and water treatment systems. Detailed instructions for common system types can also be obtained from WQA, ask for “Guidance for Sanitizing Residential Drinking Water Treatment Systems.” Again, consult with the treatment system manufacturer to avoid any unintended consequences or damage to the system. Some general tips are provided below. 

Whenever possible, physically clean devices instead of relying solely on a chemical disinfectant rinse followed by flushing. Scrubbing accessible surfaces with a disinfection solution will be far more effective than just flushing a chemical disinfectant through the treatment system. For example, using a bottle brush doused with a chemical disinfectant solution to clean the inside surface of water dispensing spouts and faucets will be far more effective than just a disinfectant flush. These brushes are available in a wide variety of sizes, for very little cost, and allow users to scrub down otherwise inaccessible surfaces where bacteria and microorganisms may have built-up during the period of vacancy.

Point-of-use (POU) filters: Replace removable cartridges with fresh filters. Follow the manufacturer’s instructions to sanitize the entire treatment system, including the dispensing faucet or dispensing spout. Flush at least two unit-volumes of water through the treatment system after sanitizing.

POU reverse osmosis (RO) systems: Replace all pre- and post-filters. Consider that the membrane module itself may need to be replaced because it may have been damaged by drying or may have been fouled with microbial growth. Follow the manufacturer’s instructions to sanitize the entire treatment system, including the dispensing faucet or dispensing spout. If the treatment system contains a storage tank, fill it and drain it at least two times after the system has been sanitized.

Softeners: Follow the manufacturer’s instructions to sanitize the entire treatment system, including the brine tank. Put the softener in rinse mode to flush out the chemical disinfectant. Once the system has been sanitized, force at least one regeneration cycle and check for hardness in the treated water. Calcium and magnesium may still be bleeding off the bed due to the prolonged stagnation. If there is hardness bleed, force a second regeneration cycle.

UV systems: Follow the manufacturer’s instructions to sanitize the entire treatment system. Be aware that the lamp may need replacing or the system may have become damaged if the lamp was lit during the entire vacancy with no flow. Follow the manufacturer’s instructions to check that the treatment system is operating normally before putting it back into service.

While performing these activities, it is important to take special precautions to protect customers and employees from exposure to the COVID-19 virus. WQA recommends the following guidelines adapted from OSHA and CDC guidance: 

  • Frequently wash hands with soap and water for at least 20 seconds;
  • When handwashing is unavailable, use a hand sanitizer with at least 60% alcohol;
  • Avoid touching your eyes, nose and mouth;
  • Avoid close contact with people who are sick;
  • Maintain a distance of at least 6 feet from other people;
  • Stay home and quarantined if you are sick, except to get medical care;
  • Cover coughs or sneezes with the inside of your elbow;
  • Wear a face mask on the job; and
  • Clean and disinfect surfaces you touch frequently with a U.S. EPA-approved disinfectant for the COVID-19 virus.

Finally, be aware that the prolonged period of stagnation may have caused corrosion problems where they may not have existed before. Watch for signs of corrosion issues, such as colored water, or consider offering lead and copper testing for your customer just to be sure. 

*This article was adapted from a guide created by the Water Quality Association and is available on its website at

About the Author

Eric Yeggy

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