Tucson Water's primary water quality goal is to protect public health and safety. In order to ensure your water is protected from harmful bacteria and other microorganisms, Tucson Water adds an effective level of disinfectant, chlorine, to the water distribution system.
Because of chlorine's effectiveness in killing germs, disinfection with chlorine provides critical protection for drinking water consumers. Around the world, millions of people suffer from waterborne diseases due to microorganisms in their drinking water. Here in the U.S., we have few waterborne disease outbreaks because the water is very carefully monitored for disease-causing organisms and most water providers add a chlorine-based disinfectant to the drinking water supply to kill existing microorganisms. In addition, chlorination can protect against contamination that may enter the public water supply after the water is pumped from the ground. With current technology, only chlorine-based disinfectants provide a lasting measurable residual disinfectant.
Tucson Water chlorinates all water wells to a target chlorine level of 0.8 to 1.2 parts per million (ppm) and seeks to maintain storage reservoirs at this chlorine level. Our goal is to be able to detect some chlorine at every point in the water distribution system as proof that the entire system is protected against harmful microorganisms. Modern technology can detect concentrations of as little as .05 ppm in water.
Many people are able to taste or smell extremely low concentrations of chlorine in water and may be able to detect the levels we try to maintain in our water system. Maintaining an adequate chlorine residual at every customer tap often means that some customers who are located closer to a chlorination point receive higher chlorine levels than those farther away. Tucson Water strives to balance the need for ensuring adequate protection for your drinking water against the possibility of customers experiencing an objectionable chlorine taste and odor. Because chlorine will naturally disappear from your water within a few hours, you may want to set an open container of tap water in your refrigerator overnight. This also saves water since you don't run the faucet until the water gets cooler.
Whenever a chlorine-based disinfectant is used in water, there is a possibility of the chlorine combining with natural organic material in the water to form compounds known as disinfection by-products (DBPs). Some of these DBPs, such as trihalomethanes, are regulated by the U.S. Environmental Protection Agency (EPA) as possible cancer-causing agents and others currently are being investigated for long-term health effects. Because Tucson's groundwater is relatively free of natural organic matter, levels of DBPs in our drinking water are extremely low. Our community must choose between the minimal long-term health risks which DBPs may represent and the certainty of waterborne diseases if the water is not disinfected.
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