OWASA changes its drinking water disinfection process from March 1 to April 1 of each year

In January 2002, OWASA began using chloramines (a compound of chlorine and ammonia) to disinfect public drinking water. Before this change, we used chlorine in the form of sodium hypochlorite for disinfection.

From March 1 to April 1 of each year, we will again use chlorine instead of chloramines to disinfect our water. The purpose of this change is to help ensure a high level of disinfection in our community's network of water mains.

North Carolina standards require us to operate the water system with chlorine as our disinfectant for one month each year. The Cities of Raleigh and Durham and Towns of Cary and Apex will similarly operate their water systems with chlorine in March.

Your water will likely have a chlorine taste or smell in March.

Customers who use OWASA drinking water for certain special purposes including kidney dialysis may need to make adjustments because the chlorine disinfection process will change some characteristics of our water.

We will ensure that water with chlorine goes through the entire system of public water mains by releasing water from fire hydrants.

Orange Water and Sewer Authority (OWASA)
400 Jones Ferry Road, Carrboro, NC 27510 telephone: 968-4421 fax: 968-4464;
e-mail: webmaster@owasa.org Website: www.owasa.org

SOME QUESTIONS AND ANSWERS ABOUT
DISINFECTION WITH CHLORINE IN MARCH

How will the change in disinfection affect my drinking water?

The public drinking water will, of course, be safe to drink in March as at other times of year, but we want our customers to be aware of what is going on and how water may be affected as indicated below.

The use of chlorine may cause your water to have a chlorine taste or smell.

Some customers' water may temporarily have a brownish tint because small amounts of iron and manganese, which are normally present in water mains, may be stirred up when we release water through fire hydrants. Similarly, air bubbles may get into the drinking water and give it a white (bubbly) appearance.

If your water becomes brownish or bubbly, please run water through a cold water faucet for 5 to 10 minutes and the water should clear up. If it does not clear up, please contact us at 968-4421. Please delay using your washing machine and dishwasher if our water is not clear.

Our water will have a pH of about 7.5 in March, compared to about 8.3 with our normal process of chloramination. (The "pH" is a measure of alkalinity/acidity; our drinking water is slightly alkaline.)

Why does OWASA normally use chloramines (or chlorine in March) to disinfect water?

In recent years, OWASA and several other water systems in the Triangle region have begun using chloramines in addition to chlorine to kill bacteria and other germs during the drinking water treatment process and for water distribution.

Before using chloramines, the utilities simply used chlorine as the disinfectant in public drinking water.

The utilities began using chloramines because they reduce the levels of certain disinfection by-products called trihalomethanes (THMs) and haloacetic acids (HAAs), which might be harmful to people at high levels. The change to water treatment with chloramines also reduces or minimizes the chlorine taste and smell of water under normal conditions.

However, chloramines are not as strong a disinfectant as chlorine. Water systems in North Carolina that use chloramines are therefore required to flush their water systems with chlorinated water once each year as a precaution.

Is chlorine in drinking water hazardous?

At the levels used in municipal drinking water, chlorine is not hazardous to people for the many normal uses of drinking water.

However, as is already the case, agencies and people who use drinking water for dialysis must remove the chlorine and chloramines so they will not be absorbed into a patient's blood. Water for dialysis is therefore filtered very carefully.

Water used in aquariums must be treated with an appropriate additive or filtered to remove chlorine or chloramines because they are toxic to fish and amphibians and may kill them.

Are some people allergic or sensitive to chlorine?

Yes, some people are. If you are sensitive to chlorine (or chloramines), you would likely have discovered this already because chlorine and chloramines have been widely used across the U.S. to disinfect drinking water. If you are sensitive to water with chlorine, please be aware of the disinfection change in March so that you can take precautions as needed. For example, you may choose to drink or otherwise use bottled water without chlorine.

Will OWASA's use of chlorine affect aquarium owners?

If you add OWASA water to your aquarium or pond in March, you will need to use an additive to neutralize both chlorine and chloramines or use an equivalent method such as special filtering. A pet supply store can give you more detailed advice about an appropriate additive or filter. (Additives typically cost less.)

Will chlorine in drinking water affect the operation of swimming pools?

If you operate a swimming pool in March, please be aware of the temporary changes in our water. We recommend that you get advice from an appropriate vendor or other technical source regarding whether and how you may need to adjust your chlorine feed level and/or pH.

Will the chlorine in drinking water affect some specialized commercial
or institutional uses of water?

As indicated above, people and agencies with dialysis equipment should be aware of and adjust to the changes in our water as needed. We recommend getting advice from an appropriate technical source, such as a filter vendor or service company, about whether to make adjustments in water filtration and processing for dialysis purposes.

If you use our drinking water for other special purposes, you may need to make some adjustments due to our use of chlorine and the lower pH of our water in March. While we are unable to provide advice about your particular water use processes, we will be glad to provide information about the specific characteristics of our drinking water in March and at any other time.

How can I get more information?

Please feel free to get in touch with us by telephone, e-mail, etc. if you have any questions or comments about our use or chlorine in March or regarding any of our services.