Preparing Your Building’s Water System Before Reopening

water flushing
Businesses and commercial offices reopening after a lengthy period away should flush their water systems to eliminate any buildup of stagnant water left sitting in pipes and plumbing. Stagnant water can affect your water quality, and cause bacteria-related illnesses, so it is important to properly flush your water system before reopening to ensure you have high-quality, fresh water for your business.

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 here.