In January, 2002, OWASA began using a compound of chlorine and ammonia called "chloramines" to disinfect drinking water. Disinfection with chloramines has improved the taste, odor and overall quality of drinking water. Before 2002, OWASA used chlorine in the form of sodium hypochlorite (bleach) for disinfection.

From March 1 through 31, OWASA will use chlorine instead of chloramines for disinfection in accord with a State drinking water quality requirement. The purpose of the chlorine disinfection in March is to help ensure a high level of disinfection in the community's network of water mains. (OWASA used chlorine for disinfection in March of 2003 through 2007 but did not in 2008 due to drought conditions and the need to avoid the related flushing of water mains.)

Some customers may notice that OWASA water will have a chlorine taste or odor in March. However, OWASA's drinking water will be safe to drink as at other times of year.

Customers may also see OWASA crews releasing water from some fire hydrants in March. The purpose of this "flushing" of water mains is to ensure that water with chlorine goes through the entire water system.

The flushing of water mains may cause some discoloration of OWASA drinking water because iron and manganese particles that settle in water mains over time may be stirred up. Air bubbles, which can make water look milky, may also get into the water system. Customers who notice discoloration or air bubbles are encouraged to run cold water through a bathtub faucet, etc. for about 5 minutes to clear up the water.

OWASA will use special equipment and a chemical to neutralize the chlorine and ammonia in the water that is released during flushing so that it will not harm fish in streams and creeks.

Customers with fish or amphibians in aquariums filled with OWASA water should continue to use chemicals as recommended by pet supply stores, etc. to neutralize chlorine and ammonia.

Customers who use OWASA water for special purposes or processes involving careful control of water characteristics, such as kidney dialysis, are encouraged to get advice from an appropriate technical source such as a filter vendor or service company about whether and how to make adjustments to their use or filtration of OWASA water during March. With chlorine disinfection in March, OWASA expects that the pH of its water will be 7.1 to 7.3, compared to the pH of 8.0 to 8.1 in months with chloramine disinfection.

OWASA will resume the use of chloramines for disinfection on April 1, 2009.

Customers are invited to contact OWASA with any questions or comments about the use of chlorine in March and about the characteristics of OWASA drinking water. 

For more information:

Rachel Monschein, Water Treatment Plant Laboratory Supervisor, 537-4227; rmonschein@owasa.org

Ken Loflin, Water Supply and Treatment Manager, 537-4232; kloflin@owasa.org