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 related to COVID-19, water quality may degrade over time.

The City of Longmont is sharing these guidelines for businesses on how to clear or flush the water in their internal water systems before reoccupying a building. The goal is to replace stagnant water in the building’s water system with fresh, high-quality water from the City’s water distribution system. Working with your building’s facility manager is highly recommended for this process.

Guidelines: It is important to follow these steps 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 (For example, for a building with multiple floors, start on the top 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. Flush hot water storage tanks (boiler and/or hot water tanks per manufacturer’s flushing instructions) to displace stagnant/discolored water with fresh water.
3. Repeat step 1 using hot water.
   • The hot water has been successfully flushed when you feel the water temperature turn from warm to hot.
4. Flush and perform preventive maintenance on point of use devices or systems, such as cooling towers, systems providing additional water treatment, etc. per the manufacturer’s recommendations as applicable.

The Centers for Disease Control and Prevention has also provided comprehensive guidelines for specific industries, such as restaurants.