Re-opening Businesses Requires a Thorough Flush of the Pipes

As businesses in California begin to open again after several weeks of closure, there are many tasks that need to be accomplished in order to open to the public safely. One such crucial task is flushing all of the building’s water systems to ensure optimal safe water quality. The Center for Disease Control (CDC) website states, “The temporary shutdown or reduced operation of a building and reductions in normal water use can create hazards for returning occupants. Two potential microbial hazards that should be considered prior to reopening after a period of building inactivity are mold and Legionella (the cause of Legionnaires disease).”

The longer water sits in the pipes of buildings not in daily use, the more likely it is that these microbial hazards as well as lead, copper and chemicals will build up in the water supply. This doesn’t just apply to drinking water: water splashes from sinks, showers, water features and flushing toilets can release these organisms into the air, which can be very harmful if inhaled. It only takes a few days for these organisms and chemicals to reach unsafe levels in pipes, filters and water softeners. This means that after several weeks of disuse, it is absolutely essential to flush your building’s water systems with fresh water before reopening your business.

The first step is to identify all sources of potable water in your building. This includes, but is not limited to: all hot and cold water taps, toilets, showers, bathtub fixtures, ice makers and water dispensers in refrigerators and freezers, decorative water features, and drinking fountains. Once you have identified all potable water sources, you can begin flushing the water system.

Start by turning on all water taps with drains and let them run for 10-15 minutes. Also, check the drains to make sure they are clear and working properly. This may need to be done in sections by floor or room, depending on the size of the building. The goal is to clear any stagnant water in the building and replace it with fresh water.

While the taps are running, flush all toilets in order to empty the bowls and tanks and refill them with fresh water.

For your refrigerators and freezers:
Dispose of any old ice, and clean the machine. Dispose of any new ice for three to five cycles. Turn on any water dispenser taps to flush the system and refill to the water line in the refrigerator.

Clean all decorative water features, making sure there is no slime or film on the surfaces. Flush the system with fresh water, refill and add appropriate disinfectant.

If the hot water in the building has any sort of unusual odor, or if the manufacturer suggests draining the system after disuse, it is recommended that you drain and refill your water heater, making sure the temperature is set to at least 140°F.

Keep in mind that you may wish to equip anyone carrying out these procedures with PPE, such as face masks to reduce the risk of inhalation of airborne bacteria from water splashes. Following these steps is essential to ensuring the health of your staff and customers as we move forward towards returning to business as usual.

Further resources and information can be found at

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