The water distribution system consists of hundreds of miles of water main and thousands of fire hydrants, and each of those hydrants 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. 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 main. Water mains are made of many different materials including cast iron, ductile iron, concrete and polyvinylchloride (PVC). Flushing the water distribution system helps to remove sediment and deposits that may have attached to the walls of the mains or simply settled out of suspension. This is a standard procedure and the water is dechlorinated to protect the environment.