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Flushing the Town's Fire Hydrants and Water Mains
Each spring, the Town of Vienna flushes water mains in its distribution system to maintain a high standard of water quality and to ensure proper and efficient operation of fire hydrants.This flushing happens at the same time that water treatment by Fairfax Water is changed to free chlorine (see below).This preventive maintenance program generally begins in early April, and flushing usually occurs between 9 p.m. to 5 a.m.

hydrant.jpg Temporary Change to Free Chlorine

 The water disinfection chemistry for the Town of Vienna will change from 
chloramines to  free chlorine from  March 25 - June 17, 2019. 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 25 - June 17, 2019), chlorine is added in an uncombined state, commonly referred to as free chlorine. Free chlorine is somewhat more volatile than combined chlorine, which allows it to react with sediments suspended during flushing. Water mains are flushed by opening 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 that is used nationwide.

Depending on your usage patterns and location within the distribution system, it may 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 during the time that 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 allows the chlorine to dissipate, thus reducing the chlorine taste.

Please note: If you have an aquarium or pond, always test the water you add to your aquatic environment, throughout the year, to ensure that it is free of chlorine before adding fish or other animals. Chemical additives that remove 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.