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Chetek Wisconsin experiments with UV light in place of chlorine

Excerpts from the May 24 edition of Chetek Alert


In the last few weeks a rumor concerning the city's tap water began circulating. Claims that the city was forgoing chlorine treatments in place of UV light treatments had people questioning the safety of their water. According to Director of Public Work Dan Knapp, the city of Chetek does not use a chlorine based water treatment system.

"We use chlorine only when we have been working on the lines to eliminate any potential bacteria that may have entered the system during repairs," stated Knapp. Following the repairs to the water tower, chlorine was used to remove any bacteria that may have developed. The chemical was then flushed through the system, which resulted in a strong chlorine smell whenever the tap water was turned on. The flush of the system is also the reason behind the running hydrants spotted by residents.

What should be catching the attention of the city's residents is Chetek's participation in a unique water treatment study, which examines the risk of acute gastrointestinal illness and fever in children who drink water from municipal systems that use groundwater. All city residents were informed my mail of the study which uses UV light purification in addition to the city's current methods of treatment.

The WAHTER study, which is being conducted by the Marshfield Clinic Research Foundation and funded through federal dollars as part of the Safe Drinking Water Amendments in 1996, is the first of its kind in the world. According to Mark Borchardt, the study's principal investigator and a scientist with MCRF's National Farm Medicine Center, the Environmental Protection Agency (EPA) commissioned the study after it was acknowledged that no one knew exactly how safe the surface and groundwater supply was under current treatment methods.

"When Congress approved the amendments they asked the EPA to conduct studies to estimate the incidence of waterborne disease in the United States. This study is designed to estimate the proportion of illness in children due to drinking groundwater," Borchardt said. "It is amazing to think that no real studies have been completed until now."

In fact, the Federal Drug Administration has done extensive studies on the safety of food, but when it came to the nation's water supply the government had "no clue," stated Borchardt. Groundwater has been perceived as pure, but between 1991-2000, more than two-thirds of the 163 waterborne infectious disease outbreaks in the U.S. were attributed to groundwater contaminated by viral, bacterial or disease-producing agents.

While disease outbreaks are alarming, there are far more sporadic individual cases, and the source of these infections is not always clear. The water sources identified as needing to be studied were ground and surface water. The federal governmental set aside $3 million for the research. The studies on surface water began first because it was believed that the greater source of contamination would be found here. "The study was held in Davenport, Iowa. What they found is that there was only a small risk of contamination," Borchardt noted. "Considering the source of water is the Mississippi River, this was very good news."

Borchardt says that the findings are reassuring because it gave scientific proof to the fact that standard water treatment methods are being effective. However, the study used all of the funds the government had set aside delaying the groundwater studies. Last year, Borchardt was awarded $1.8 million by the EPA for his proposal. Lighting up Chetek's water

"Instead of installing a UV light system on individual household taps and asking people to only take water from this one source, we realized that people are exposed to water through many sources," the scientist explained. By treating a community's entire water supply with a Wedeco UV light system, the Marshfield researchers could better assess the impact of the treatments. "I think one of the reasons this approach hasn't been taken before is because nobody believed they could get entire communities to participate, but they don't know Wisconsin," stated Borchardt.

Fourteen Wisconsin communities from a pool of 40 were selected to participate in the program. Criteria for selection was based on three factors: the city's water must come from a sand/gravel or sandstone aquifer, the number of wells feeding the communities was limited, and a sufficient number of families with children would be available to participate in the study.

"Test communities are being given a chance to use key technology free of charge," stated Borchardt. "This is equipment that is expensive to purchase and install, but it is being made available through federal funding." The plan is that after six months, the two sets of communities will "cross over," meaning the ultraviolet light units will be moved to the original control communities. All 14 communities will be tracked for another six months.

After speaking with Knapp, Borchardt determined that Chetek would be one of the test communities because it met the main criteria. Currently, every person in the city is using and consuming UV light treated water. Seven control communities will continue current water treatment practices. Surveillance for gastrointestinal illness and fever will be conducted among children in participating households.

"Among the 14 communities in this study, over 1,780 people have already agreed to participate," Borchardt said. "In Rice Lake we had to turn people away." Borchardt added that the communities need to understand that there is no danger associated with the level of UV light being used in the study.

Ultraviolet disinfection uses a UV light source, which is enclosed in a transparent protective sleeve and placed in a water flow chamber. When ultraviolet energy is absorbed by the reproductive mechanisms of bacteria and viruses, the genetic material (DNA/RNA) is rearranged and they can no longer reproduce. The organism is then considered dead, eliminating the risk of contamination.

UV treatments disinfect water without adding chemicals. It does not create new chemical complexes, produce any bi-products, alter the taste, pH, or other properties of the water, or remove any beneficial minerals in the water.

For this reason, UV light treatments are also considered environmentally friendly. Studies show that ultraviolet devices are most effective when the water has already been partially treated, and only the cleanest water passes through the UV flow chamber. In the U.S., chemical treatment with chlorine remains the primary method for disinfecting drinking water.

However, chlorine can produce chemical by-products that have been linked to cancer. Such byproducts are also coming under stricter regulations in the new EPA rules for drinking water. "If we were to try to introduce chlorine today with the protections in place from the EPA, we couldn't do it," Borchardt added.

The EPA started including UV disinfection as an approved water treatment method in 1998. When chlorine gas or sodium hypochlorite are used to disinfect water, they react with organic compounds in the water to form potentially harmful levels of the chemical by-products trihalomethanes (THMs) and haloacetic acids, both of which are carcinogenic and regulated by the U.S. EPA.

Chlorine also fails to kill some infectious microbes, such as the protozoan parasite Cryptosporidium. Known as "Crypto," in the last two decades the parasite has become recognized as one of the most common causes of waterborne disease among people in the U.S., according to the Centers for Disease Control and Prevention. The organism, Cryptosporidium, caused a major epidemic infecting 400,000 people in Milwaukee through the drinking water in 1993.


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