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Reopening Building Plumbing after Temporary Closings

For Owners of Temporarily of Partially Shut Down Business,

Church, or School Buildings


Iredell Water Corporation is advising building owners to flush water lines in buildings that have largely been closed during the past several weeks amid the Covid-19 pandemic.

Water held unused in building pipes while businesses or activities are shut down or have unused floors or sections becomes stagnant.  Conditions may develop increasing the risk for the growth and spread of waterborne bacteria, such as Legionella or biofilm, in the building piping.  Disinfectant in the water, such as chlorine, will likely dissipate or become undetectable. Actions are necessary to ensure the water in the building is safe as well as taste and odor free before resumption of normal water use. 

Clearing the water lines, known as flushing, can be done by running the tap water for an extended period in buildings. This process will clear the stagnant and potentially contaminated water.

For commercial buildings

Iredell Water Corporation advises building managers or owners to consider flushing the water lines to ensure the water in the building is safe, as well as taste and odor free, before resumption of normal water use.  Different points of use should be inspected starting with the fixtures closest to the water source. These could include:

  • Sinks
  • Showerheads
  • Toilets
  • Water fountains
  • Ice Makers
  • Water heaters
  • Water features
  • Hot tubs

Steps to consider before reopening a building:

  1. Flush your water system
    1. Flush hot and cold water through all points of use (e.g., showers, sink faucets)
    2. Flushing may need to occur in segments (e.g., floors or individual rooms) due to facility size and water pressure. The purpose of building flushing is to replace all water inside building piping with fresh water.
  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 prolonged period of disuse. Ensure that all maintenance activities are carried out according to the manufacturer's instructions or by professionals.
    2. Make sure that your water heater is set to at least 120°F
    3. Higher temperatures can further reduce the risk of contaminated water, but ensure that you take measures to prevent scalding if you water heater is set to >130°F
  3. Ensure hot tubs/spas are safe for use
    1. Check for existing guidelines from your local or state regulatory agency before use
    2. Ensure that hot tubs/spas are free of visible slime or biofilm before filling with water
  4. Ensure cooling towers are clean and well-maintained
    1. Ensure that the tower and basin are free of visible slime or biofilm before use
  5. Ensure safety equipment including fire sprinkler systems, eye wash stations, and safety showers are clean and well-maintained
  6. Replace all point-of-use filters, including the filter in refrigerators or ice makers.  
  7. Clean all decorative water features, such as fountains.

Iredell Water Corporation recommends that individual entities research guidelines that pertain to their respective industries and buildings.

Resources include: