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Flushing the Town's Fire Hydrants and Water Mains
Each spring the Town of Vienna flushes the water mains in its distribution system to maintain a high standard of water quality and to ensure proper and efficient operation of the fire hydrants. This flushing is done at the same time that water treatment is changed to free chlorine (see below). The preventive maintenance program begins in early April, and flushing usually occurs between 9 pm to 5 am.
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hydrant.jpg Temporary Change to Free Chlorine

 The water disinfection chemistry for the Town of Vienna will be changing  from 
chloramines  to free chlorine from  March 28 – June 20, 2016. This is an annual  program to allow Vienna  and others in the Fairfax Water service area to perform annual  fire hydrant flushing.

 During this period, a change is made in the water treatment process to help facilitate an  effective flushing program.  The treatment used throughout the rest of the year is  chloramine, also known as combined chlorine which is added to the water as the primary  disinfectant.

During this water chemistry change ( March 28 – June 20, 2016), chlorine is added in an uncombined state, commonly referred to as free chlorine. Free chlorine is somewhat more volatile than combined, which allows it to react with sediments suspended during flushing. Water mains are flushed by opening the fire hydrants and allowing the water to flow freely for a short period of time.  This also enables the Town to test and perform routine maintenance on the more than 800 fire hydrants within its service area.

The use of free chlorine for this short period of time also helps control biological film, known as biofilm which is found in all water pipes and can lead to water quality problems if not controlled. Biofilm can become accustomed to the chloramine disinfectant that is routinely used. By switching to free chlorine the biofilm is “shocked” and weakened. Using fire hydrants to flush our water system, combined with the disinfectant change, is a very effective method for controlling biofilm; this process is used nationwide.

Depending on your usage patterns and location within the distribution system, it could take up to a week for your drinking water to transition from combined to free chlorine or from free chlorine to combined chlorine at the conclusion of the disinfection chemistry change.

You may notice a chlorine taste and odor in your drinking water while free chlorine is utilized. If you are especially sensitive to the taste and odor of chlorine, try keeping an open container of drinking water in your refrigerator. This will enable the chlorine to dissipate, thus reducing the chlorine taste.

Please note: If you have an aquarium or pond, throughout the year always test the water you add to your aquatic environment to be sure it is free of chlorine before adding fish or other animals. Chemical additives with directions for removing either free chlorine or chloramines from water for use in fish tanks or ponds are available at pet/fish supply stores. 


Experiencing Discolored Water

Flushing may result in some discoloration and the presence of sediment in the water reaching your home or business. These conditions are not harmful and should be of short duration. If you encounter discolored water in your home, run the cold water faucet until the water is clear. The Town appreciates your tolerance of this inconvenience. 

Reporting Illegal Use of Fire Hydrants
Any use of a fire hydrant can cause discoloration or sediment in the water lines. If you suspect someone is using a fire hydrant illegally, please notify the police immediately at (703) 255-6366

Additional Details
If you need more information, please call the Water and Sewer Customer Service Office at (703) 255-6385.