What is the change in the disinfection process during the flushing period?

During the flushing period, a slight change is made in the water treatment process to facilitate an effective flushing program.  Chlorine combined with ammonia is known as chloramines. Throughout most of the year, chloramines (also known as combined chlorine) are 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). This temporary change in the water treatment process is important because it keeps bacteria from forming resistances to the usual disinfection process.

Free chlorine is quicker acting than combined chlorine, which allows it to react with sediments suspended during flushing. Chloramines tend to take longer to react, but are stable in the water for longer periods of time which is the reason that they are used the majority of the year. Colder water allows the free chlorine to stay in the water longer and it is the reason that flushing occurs during cold water periods in the Spring.  

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

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 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.  See our Water Quality Reports (LINK) for more information.

Show All Answers

1. What is the Annual Water Main Flushing Program?
2. When will crews be in my area?
3. What is the change in the disinfection process during the flushing period?
4. What are chloramines?
5. What is free chlorine?
6. Why is the water that Utilities distributes to customers disinfected with free chlorine instead of chloramines each Spring?
7. How long will free chlorine be used to disinfect my drinking water this year?
8. Is water disinfected with either free chlorine or chloramines safe to consume?
9. Could water disinfected with either free chlorine or chloramines be harmful to dialysis patients if it is used in the dialysis process?
10. Will my water taste different during the temporary conversion to free chlorine?
11. Will chloramines affect household plumbing, pipes and/or water heaters?
12. How can I remove the chlorine taste from my water?
13. Will pool owners need to treat water differently?
14. What does the term hydrant flushing mean?
15. Could I see a drop in water pressure due to hydrant flushing in my area?
16. Can hydrant flushing in my area cause cloudiness or sediment in my water?
17. How can I get more information about Spotsylvania County Utilities water quality?