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Water System Precautions for Idle Facilities

Water System Precautions for Idle Facilities

If your building or facility has been mostly vacant for several weeks or longer, the water in your internal plumbing is stale from sitting idle. Unused water that has been sitting in pipes for extended periods may appear cloudy or have an unpleasant taste or odor. Depending on the building and its plumbing, Legionella, metal leaching, and other hazards can also pose a health risk.

Commercial and institutional building water systems are not designed for prolonged periods of inactivity and should be flushed thoroughly prior to use. While this is a common practice for seasonally operated facilities such as schools and parks, it is not for the many businesses, houses of worship, social clubs, day care facilities and restaurants which have been idled during the Covid-19 crisis.

At a minimum building or facility managers should:

  • Turn on every fixture and run cold water until it feels cool and fresh. Fresh water from the main will feel cooler than water that has been sitting in your building’s plumbing. It may take longer for fresh water to reach faucets in larger buildings.
  • Flush every toilet as well.
  • Next, run the hot water at every tap until it gets fully hot. This will get fresh water into your building’s hot water lines. For this to be effective, flush hot water only after all cold taps have been flushed.
  • Check cold water supply for chlorine to indicate fresh water has entered the system. (Contact the Water Plant for testing information)
  • Consider draining storage tanks like water heaters and softeners, and check for sediment buildup.
  • Check aerators, filters, showerheads and other equipment for particles and clean as necessary.
  • Clean ice machines, and dispose of three batches of ice after flushing the system.
  • Maintain any other appliance or system with a water connection, such as fire sprinklers, drinking fountains, coffee makers.
  • Replace all point-of-use filters, including the filter in refrigerators.

For more information and recommendations from authoritative sources, please visit:

  • For Plumbers - International Association of Plumbing and Mechanical Officials (IAPMO): Coronavirus Resources

For information on City of Highland Park’s water quality, please visit:

If you need additional information on City’s water testing procedures, please contact Department of Public Work's Water Production Division team at 847.433.4355 or via

If you need information on the City’s building permit requirements including the plumbing code, please visit the Community Development Department's Building page or call 847.432.0808.