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Posted on: April 2, 2021

(COVID -19) Ensuring the Safety of Your Building’s Water System and Devices

As Vermont considers reopening, commercial facility and even homes, that were vacant or had diminished use for more than 3 weeks should flush their water systems.

Stagnant, or standing water can cause conditions that increase the risk for growth and spread of Legionella and other biofilm-associated bacteria.  When water is stagnant, hot water temperatures can decrease to the legionella growth temperature range (77-108°F).  Stagnant water can also lead to low or undetectable levels of disinfectant, such as chlorine.  Ensure that your water is safe to use after a prolonged shutdown to minimize the risk of Legionnaire’s disease and other diseases associated with water. 

This information issued by the U.S. Centers for Disease Control (CDC), is useful for residential homes and businesses that have had prolonged shutdowns, including seasonal non-use, and mandated pandemic responses.


  1. Develop a comprehensive water management program for your water system and all devices that use water.  Guidance to help with this process is available from the CDC and others.
  2. Ensure your water heater is properly maintained and the temperature is correctly set.
    1. Determine if your manufacturer recommends draining the water heater after a long period of disuse.  Ensure that all maintenance activities are carried out according to the manufacturer’s instructions or by professionals.
    2. Make sure your water heater is set to at least 120°F.
    3. Higher temperatures can further reduce the risk of Legionella growth, but ensure you take measures to prevent scalding if your water heater is set to > 130°F.
  3. Flush your water system
    1. Flush hot and cold water through all points of use (eg. Showers, sink faucets)
      1. Flushing may need to occur in segments (eg. Floors or individual room) due to the facility size and water pressure.  The purpose of building flushing is to replace all water inside building piping with fresh water.
    2. Flush until hot water reaches its maximum temperature.
  4. Clean all decorative water features, such as fountains.
    1. Be sure to follow any recommended manufacturer guidelines for cleaning.
    2. Ensure that decorative water features are free of visible slime or biofilm.
    3. After the water feature has been refilled, measure disinfectant levels to ensure the water is safe for use.
  5.  Ensure hot tubs/spas are safe for use.
    1. Check existing guidelines from your local or state regulatory agency before use.
    2. Ensure that the hot tubs/spas are free of visible slime or biofilm before filling with water.
    3. Perform a hot tub/spa disinfection procedure before use.
  6. Ensure cooling towers are clean and well maintained.
    1. Ensure that cooling towers are maintained (including start-up and shut-down procedures) per manufacturers guidelines and industry best practices.
    2. Ensure the tower and basin are free of visible slime and biofilm before use.
  7. Ensure safety equipment including fire sprinkler systems, eye wash stations, and safety showers are clean and well maintained.
    1. Regularly flush, clean, and disinfect these systems according to manufacturers’ recommendations.
  8. Maintain your water system
    1. Follow your water management program, document activities, and promptly intervene when problems arise. 

Avoiding Water Leaks from Frozen and Broken Water or Sprinkler Systems

The first major cold spell can result in a broken water or sprinkler pipe, with water damage resulting.

  1. Preplan.  Think ahead about known cold spots in your buildings and plan how to adequately heat areas where water or sprinkler lines run.  In some cases, this can be as simple as opening a closet door or turning on the heat.
  2. Have your sprinkler system serviced by a qualified vendor at least annually.   This service should include system tests and flowing water (as appropriate).
  3. For dry sprinkler systems, learn where the systems low spots are and make sure your vendor drains the water and condensation from them.
  4. Furnaces and boilers can and do fail.  Equip infrequently used buildings with low temperature sensors to alert you if a heat source malfunctions.  Follow up with repairs to limit any damage.

(From VLCT Risk Management Services, Sept-Oct 2020, Fred Satink, Deputy Director, Underwriting and Loss Control)

Please call Jay Nadeau, Champlain Water District Retail Director, at 861-4817 if you have any questions regarding this information.

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