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If you notice any changes to your drinking water, please contact the Department of Public Works at (703) 435-6853 or email

Click here to View Water Quality Reports

Click here to learn more about the Automated Meter Reading (AMR) Program


Service Repairs

Hydrant Flushing
Each spring, The Town of Herndon flushes its water mains by opening fire hydrants and allowing them to flow freely for a short period of time. We do this to maintain the high quality of water in our distribution system.

Flushing may result in some temporary discoloration and the presence of sediment in your water. These conditions are not harmful and should be of very short duration.  Running your cold water for a few moments should help clear the line. 

If you have questions about this program or the work being conducted in your area, you may contact the Department of Public Works at (703) 435-6860 for more information.

During this period of time, a slight change is made in the water treatment process to facilitate an effective flushing program. Throughout the year, chloramines, or combined chlorine, is added to the water as the primary disinfectant. During the spring flushing program, chlorine is added in an uncombined state, commonly referred to as free chlorine. Free chlorine is somewhat more volatile than combined, providing exceptional availability to react with sediments suspended during flushing. Fairfax Water will use free chlorine as the primary disinfectant from April through July. Depending on your location within the distribution system and usage patterns, it could take up to a week for your drinking water to transition from combined to free chlorine at the beginning of April, or from free chlorine to combined chlorine at the beginning of July.

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. Remember - drinking water has a shelf life! Change out the water in your refrigerated container weekly.

Please note: If you have an aquarium or pond always test the water you add to your aquatic environment to be sure it is free of any 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. 

Valve Maintenance

The Department of Public Works conducts water valve maintenance throughout the town.  The purpose of the program is to exercise main line valves throughout the distribution system to assure reliable operation and maintain water quality.  The American Water Works Association recommends operation of main line valves periodically to prevent build-up of deposits which may render the valve inoperable.

A main line valve is a valve which is installed at certain points in the water main system, usually at an intersection where the main may run in different directions or where access needs to be controlled remotely as with a fire hydrant. The valves provide a means of isolating small lengths of main in the event of a necessary shut down for emergencies or maintenance. The valves are generally in the street located under small lids covering valve boxes, usually about 6 inches in diameter. The program will provide an opportunity to check the condition of the valve box, as well as all aspects of valve operation.

During this program, crews will exercise the valves by operating the valve through a full cycle and returning it to its normal position. Where valves are exercised, a fire hydrant will be flowed to ensure that the water in the mains will remain clear.

All care will be taken to minimize any potential impact on water quality. Even with these precautions, some discolored water is possible. Flushing may result in some temporary discoloration and the presence of sediment in your water. These conditions are not harmful and should be of short duration. If you have questions about this program or the work being conducted in your area, you may contact the Department of Public Works at (703) 435-6860 or email for more information.
Avoiding winter water disasters
Water has a unique property in that it expands as it freezes. This expansion puts tremendous pressure on whatever is containing it, including metal or plastic pipes. No matter the "strength" of a container, expanding water can cause pipes to break. Pipes that freeze most frequently are those that are exposed to severe cold, like outdoor hose bibs, swimming pool supply lines, water sprinkler lines, and water supply pipes in unheated interior areas like basements and crawl spaces, attics, garages, or kitchen cabinets. Pipes that run against exterior walls that have little or no insulation are also subject to freezing.  Click here to read tips on how to prevent winter water disasters.

Related Links

Sanitary Sewer Lateral Repair & Replacement Program
Pay your Water Bill Online
Electronic Funds Transfer Form
Hydrant Meter Rental Application
Tips to Prevent Winter Water Diasters
Water Main Design & Construction Standards
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777 Lynn Street
Herndon, VA  20170
(703) 435-6853

P.O. Box 427
Herndon, VA  20172-0427
(703) 435-6813

1479 Sterling Road
Herndon, VA  20170
(703) 435-6860


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