Preparing Your Building’s Water System Before Reopening

water flushing

Are you reopening?

Businesses, schools and commercial offices reopening after a lengthy period away should flush their water systems to eliminate any buildup sitting in pipes and plumbing that have not been used for a while. Stagnant water can affect your water quality and cause illness, so it is important to properly flush your water system before reopening to ensure you have high-quality, fresh water.

Flushing Your System

  • Flush hot and cold water through all plumbing sources (sinks, showers, faucets, etc.) by turning on the tap for both your hot and cold water.
  • Flush your hot water until the water reaches its maximum temperature; flush your cold water until it reaches a steady, cool temperature (typically 10 minutes).
  • Larger businesses may need to flush for longer periods and in segments (room by room) to maintain proper water pressure.
  • Dispose of old ice, and flush the water source for your icemaker.

Clean Faucet Aerators and Replace Water Filters

  • Remove and clean your aerators on your taps.
  • If you have water filters, replacing them will also keep your water supply fresh.


  • If you have questions about flushing your system or about your water quality, contact our Water Quality Lab at 415.945.1550.
  • For more information about flushing your system before reopening, visit the Environmental Protection Agency's website.