When buildings are unoccupied for extended periods of time and water is not being regularly used, the water can sit and become stagnant. When this happens, such as during business shutdowns during COVID-19, water quality will degrade over time and may become discolored.

The City of Westminster is sharing these tips for businesses on how to clear or flush the water in their internal water systems before reoccupying the building. The goal is to replace stagnant water in the building’s water system with fresh, high-quality water from Westminster’s distribution system. The city recommends working with your building’s engineer or facility manager for this process.

It is important to follow these tips in the order outlined below:

1. Turn on the cold-water inside the building (break room sinks, drinking fountains, utility closets, restrooms, etc.) on each floor.

  • Start from the furthest point away from where water enters the building (e.g. for a building with two floors, start on the second floor and work your way to the first floor. Remember to run cold water only.
  • The cold water has been successfully flushed when you feel the water temperature go from slightly warm to cold.

2. Repeat step 1 using hot water. Flush hot water storage tanks (boiler and/or hot water tanks per manufacturer’s flushing instructions) to displace stagnant/discolored water with fresh water.

  • The hot water has been successfully flushed when you feel the water temperature turn from warm to hot.

3. Flush and perform preventative maintenance on point of use devices, such as cooling units, systems providing additional water treatment, etc. per the manufacturer’s recommendations as applicable.

4. Flushing irrigation and fire suppression systems is not required for reopening. Follow your regular operation and maintenance schedule for these systems.

The Centers for Disease Control and Prevention have also provided comprehensive guidelines for specific industries, such as hotels or restaurants. Those are available here.

Once all domestic water service lines, internal plumbing, and point of use devices/systems are flushed/properly maintained, the building can be occupied.