Environmental Services
Annual Water Line Flushing FAQs
Frequently Asked Questions about the Temporary Conversion to Free Chlorine as the Water Distribution System Disinfectant
Q: Why is the Washington Aqueduct (our water supplier) changing the water disinfectant from Chloramines to Free Chlorine?
A: Temporarily converting from chloramines to free chlorine is done to accompany the annual process of flushing of our drinking water distribution system. A biological film, known as biofilm, is found in all water pipes. It 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 for a short period of time, the biofilm is ‘shocked’ and weakened. Using fire hydrants to conduct a system-wide flushing of our distribution mains, combined with the disinfectant change is very effective method for controlling biofilm that is used nationwide. Find out more.
Q: Is there anything I will notice during the conversion?
A: You may notice a slight chlorine taste and smell to the water during this period. This is normal and poses not health risk. If you would like to minimize this odor, you could put a pitcher of water in the refrigerator until cold and then drink.
You may also see County crews with fire hydrants open and water flowing. This is part of the water main flushing activities. The flushing may result in some increased cloudiness, or turbidity, in streams, but crews will use treatment to remove chlorine from the water before it is flushed into the storm sewer to minimize any adverse effects on streams from the flushing.
Q: How long will it last?
A:The switch will start on March 21, 2001 and end on Monday, May 2, 2011.
Q: Why is it being done now?
A: Spring is the ideal season for water line flushing. During this time, the potential for hard freezing diminishes (thereby avoiding icy roads in the vicinity of hydrants) and demand for water supply is still low before the hotter summer months.
Q: Is this the first time you have temporarily switched the disinfectant?
A: No. Generally we conduct this switch once per year.
Q: Do other water systems make this temporary disinfectant switch?
A: Yes. This is common industry practice. Many utilities throughout the country that use chloramines as a distribution system disinfectant, convert to free chlorine annually for water line flushing.
Q: How will this temporary switch affect kidney dialysis procedures?
A: The processes already in place to remove chloramines in the water will remove free chlorine. No change or adjustment should be needed. However if you have any concerns, please contact your health care provider for more information.
Q: I have a fish tank. How will it affect my fish?
A: The processes already in place to remove chloramines in the water will remove free chlorine. No change or adjustment should be needed. However if you have any concerns, please contact a pet store or aquarium expert for more information.
Q: I recently moved to Arlington from out of state. Right before I moved my local water utility was publicizing the switch from free chlorine to chloramines and the need for dialysis centers and fish tank owners to prepare for the change. Why is this different?
A: All methods for removing chloramines will also remove chlorine, but the reverse is not true. In 2000 the Washington Aqueduct (WA) switched from using free chlorine to chloramines as the primary disinfectant. Affected parties living in Arlington should have already adjusted for chloramines. No adjustment should be needed for this temporary conversion to free chlorine, however be sure to follow the manufacturer’s instructions for your dechlorination equipment. Adjustments should not be necessary when WA switches back to chloramines in May.
Q: Who can I contact with additional questions or concerns?
A: Please call our Water Control Center at 703.228.6555.
Read additional Frequently Asked Questions about the Temporary Conversion to Free Chlorine as the Water Distribution System Disinfectant.
