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(1) Raw water from University Lake and/or Cane Creek is pumped to the Jones Ferry Road Water Treatment Plant and (2) enters through the headworks facility, where non-toxic chemicals are added to make solid particles clump together and improve taste and odor. (3) Water is then pumped to either a “pulsator” or sedimentation basins, which allow time for solids to settle. (4) As water is pumped to filters, a liquid form of chlorine (bleach) is added for initial disinfection. (5) Water flows downward through dual media filters (sand and anthracite coal), where additional particles are removed. (6) The water enters the post-filtration stage, where we add fluoride for dental health and a chemical to set the pH (acidity/alkalinity) at the right level. The water then flows to the 1.5 million gallon clearwell (7) for temporary storage. Ammonia is added and it combines with chlorine to form “chloramines” to disinfect the water. (Please see the part of this report on “Additional Characteristics of our Water” for important information about chloramines and fish kept in aquariums.) Millions of gallons are pumped daily to one of several elevated storage tanks (8), which provide pressure so finished water can be delivered to your tap through a 330-plus mile network of water lines. |
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Drinking Water Quality: 2003 Test Results In 2003, the Laboratory staff of four people at our Jones Ferry Road Water Treatment Plant tested our drinking water more than 43 , 000 times for over 100 substances in accord with State and Federal requirements. Listed below are the substances that were detected, all of which were below the regulatory limits. To get a list of all test results including substances not detected, please click here or call our Water Treatment Plant Laboratory staff at 537-4227. There were no violations of the federal Safe Drinking Water Act or other related State and federal standards. |
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Glossary Maximum Contaminant Level Goal (MCLG) - the level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety. Maximum Contaminant Level (MCL) - the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology. MCLs are set at very stringent levels. A person would have to drink 2 liters (about two quarts) of water every day at the MCL level for a lifetime to have a one-in-a-million chance of having adverse health effects from many regulated contaminants. Parts per million (ppm) - one part per million corresponds to one minute in two years or one penny in $10,000. One ppm is equivalent to 1 milligram per liter (mg/L). Parts per billion (ppb) - one part per billion corresponds to one minute in 2,000 years, or one penny in $10 million. One ppb is equivalent to 1 microgram per liter (ug/L). Picocuries per liter (pCi/L) - a measure of the radioactivity in water. (A picocurie is one trillionth of a curie.) Nephelometric Turbidity Unit (NTU) - a measure of cloudiness in water. Turbidity over 5 NTU is just noticeable to the average person. Action Level ( AL ) - the concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow. Treatment Technique (TT) - a required process intended to reduce the level of a contaminant in drinking water. Below Detectable Level (BDL) - a concentration that is below the level that can be detected with required tests. Disinfection by-products - Substances such as haloacetic acids and trihalomethanes, which are formed when chlorine or chloramines used to disinfect drinking waster react chemically with organic compounds naturally present in the water from our lakes. Federal standards require public water systems to limit the level of haloacetic acids and trihalomethanes because they could be harmful at high levels. Disinfection by-product precursors - Organic carbon compounds that can combine with disinfectants to form haloacetic acids and trihalomethanes as discussed above. Maximum Residual Disinfectant Level (MRDL) – The highest level of a disinfectant allowed in drinking water. Disinfection is necessary to control microbial contaminants in drinking water. MRDLG – Maximum Residual Disinfection Level Goal (MRDLG) – The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of using disinfectants to control microbial contaminants. Unregulated contaminants – Substances for which the U.S. Environmental Protection Agency (EPA) has not established drinking water standards. Water systems test for unregulated contaminants so that the EPA can monitor the presence of unregulated contaminants in drinking water and decide whether additional regulations are needed. 90 th Percentile – The contaminant level that 90 percent of the samples for a given water characteristic were below. |
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Additional characteristics We disinfect our water with “chloramines,” a compound of chlorine and ammonia, in the months other than March. In March, we instead use chlorine for disinfection in accord with State requirements. Chloramines and chlorine are toxic to fish and amphibians such as frogs. If you have fish in an aquarium with OWASA water, please contact a pet supply store for advice on how to neutralize chloramines and chlorine to protect your fish. OWASA’s drinking water is very “soft”—it has a low mineral content (dissolved calcium, etc.) of about 2 grains per gallon of water. This means that a small amount of soap is needed for washing dishes, clothes, your hands, etc. Our water is slightly alkaline. On the scale of acidity to alkalinity, our water normally has a pH of about 8.3 (in the month of March, we adjust the pH to about 7.4 when we temporarily use chlorine instead of chloramines to disinfect the water). The pH of our water helps make the water treatment process work effectively and helps prevent corrosion in both public water mains and private plumbing system pipes. Sometimes our water looks rusty or bubbly because work that we do on the water system may stir up iron or other minerals that have accumulated in a water main, or because air may enter water mains during a repair. Running a cold water faucet as in a bathtub, etc. for 5 to 10 minutes should clear up the discoloration. If the water does not clear up, please contact us at 968-4421. The water should be clear before washing clothes, etc. |
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If you have any questions about this report or concerning your water utility, please contact our Water Treatment Plant Laboratory Supervisor at (919) 537-4227. Our postal address, e-mail address and fax numbers are also listed in this brochure. We appreciate the opportunity to respond to any questions you may have and we welcome your feedback. Atención How to contact us: OWASA is the public, nonprofit, community-owned water and sewer agency serving the Carrboro-Chapel Hill community. EPA’s Drinking Water Hotline: (800) 426-4791 This report on the quality of drinking water in 2003 was distributed in June, 2004
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