Hydrant Flushing

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Fire Hydrant "Flushing"

(AKA) Fire Hydrant Maintenance and Water Distribution System Flushing

Why Do We "Flush" Fire Hydrants?

The City of Ankeny’s water distribution system consists of more than 280 miles of water mains and almost 4,000 fire hydrants.  Each hydrant needs to be operated periodically to lubricate the internal mechanisms and check the overall functionality.  If a deficiency is discovered during this inspection, most maintenance can be performed immediately.  More significant repairs will be scheduled to keep the hydrant working properly.  The end result is that the fire hydrants in your neighborhood are available for fire protection if there is ever a need.

Water chemistry can be very complex.  Temperature and time can change how water reacts with the water mains.  The City’s mains are made of many different materials - cast iron, ductile iron, concrete and polyvinylchloride (PVC).  Flushing the water distribution system helps remove sediment and deposits that may have attached to the walls of the mains or simply settled out of suspension.   The normal velocity of water in the mains is as slow as less than 1 foot per second.  In order to move the sediment and deposits, we have to increase the velocity in the mains to more than 3 feet per second.  This requires large volumes of water - between 500 and 1000 gallons per minute - depending on the diameter of the water main.  This is why you may see us “flushing” fire hydrants and letting the water run down the street.  This is a standard procedure and the water is dechlorinated to protect the environment.

How Often Are Hydrants "Flushed"?

Since the City has almost 4,000 hydrants in the water distribution system, it is not economically feasible to flush each hydrant annually.  The City’s Fire Department and the Public Works Department - Utilities Division partner to maximize the number of fire hydrants flushed annually.  We are currently on a 3-year cycle with a goal of getting to a 2-year cycle in the near future.  Some of the higher priority areas like schools, health care facilities and older, smaller cast iron water mains are flushed on an annual basis.

Will Hydrant "Flushing" Affect Your Water?

If you happen to be using water when the fire hydrant “flushing” process is occurring in your neighborhood, the water that we are scouring out of the water distribution system could be drawn into your home’s plumbing system.  Although the water may be discolored, smell different, and/or have a slightly different taste, it is safe to use.  However if it gets into your ice maker or laundry, there are some simple remedies.  For ice, after the water returns to normal, discard the discolored ice and the new ice will be fine.  For most laundry loads, you may not even notice a change; however, white or light colored laundry may be affected.  If you do observe a rust color in white or light-colored laundry, please contact the City’s Utilities Customer Service at 963-3565.  The City has a product that will remove the rust in most cases.

Questions or Concerns?

The City of Ankeny appreciates your patience and understanding as we strive to provide you and our other customers with the high quality potable water that has been our standard for many years.  We work hard to keep all of the City’s water distribution system operational in order to provide high quality potable water and fire protection for our residents, businesses, and visitors.

Please contact Ankeny’s Utilities Customer Service at 963-3565 for assistance with your questions and concerns.