Flushing Water Systems for Reopening

Recommendations for preparing your building/facility for reopening

State and local Stay-at-Home Orders have changed the way our communities shop, eat, do business, and go to school. When buildings are vacant or operating at significantly reduced capacity for a long time, water is left sitting in pipes and devices. Disease-causing microorganisms, like the one that causes Legionnaires’ disease, can begin to grow. Corrosion control can be impacted. To make sure you remove any stale and potentially unhealthy water in your building’s system, we are asking you to follow these steps as you prepare to reopen.

The key to preparing your facility is to flush the water systems and devices. For larger buildings, a single flush isn’t enough to re-establish good water quality. It’s important to plan ahead and include flushing as a part of the cleaning and routine maintenance done before reopening. This also protects the health of any staff or occupants still working on the premises. We recommend performing a final flush in the 24 to 48 hours before a building officially reopens.


Flushing in stages is best. Begin at the main service line and include all the plumbing, storage tanks, fixtures, and equipment such as water fountains and ice machines. The first flush pulls out stale water, while follow-up flushes draw freshly-treated water through the building. The longer service is interrupted the more flushing is needed.

Consider the following steps when flushing your facilities:

  • Flush all faucets (remove faucet aerators, if possible) for 10 to 30 minutes.
  • Open all outlets at once to flush the service line and then open them again, individually, starting near where the water enters the building.
  • Flush cold water first. Then flush hot water until it reaches its maximum temperature.
  • Follow manufacturer recommendations to flush water fountains, hot water tanks, hot water recirculating loops, ice makers, dishwashers, humidifiers, and cooling towers.

Please consider capturing and reusing the flushed water for outdoor watering or cleaning purposes.

More Information

Flushing pipes is a precaution that should be taken after any shutdown of more than a few days. Depending on the complexity of a building’s water system, facility managers should develop a comprehensive water management program for this process. It should not replace a facility-specific Water Management Plan.

Please visit our Flushing Water Systems FAQs for additional information about flushing pipes after a shutdown.

There is no evidence that the coronavirus can survive in treated drinking water.