These limits have been established to protect the water ecosystem and downstream users. Under the CWA, these facilities have water-quality limits that their effluent must meet. Industrial manufacturers and wastewater treatment plants discharge effluent from their processes into lakes and rivers. It drains into rivers, lakes, and streams either naturally or via constructed storm-water-drainage systems. Water falls to the earth in the form of precipitation. Consider the water cycle and the water-use cycle. The requirements of the CWA and SDWA are different, but interrelated. The list includes microorganisms, disinfectants and disinfection by-products, inorganic chemicals, organic chemicals, and radionuclides. The SDWA sets maximum contaminant levels (MCLs) and treatment techniques (TTs) that drinking water must meet to be considered safe forĬonsumption. Storm water and discharges into surface water are also regulated under the CWA. The EPA additionally regulates wastewater, but under the requirements of the Clean Water Act (CWA). The EPA, under the requirements of the SDWA, regulates drinking water in the United States. Water Quality Regulations in the United States As the United States entered the twenty-first century, researchers were collaborating with scientists around the world to continuously improve water quality and treatment, and openly share their research findings. The United States drinking water community sees this as an important step to protect customers and the water system from bacteriological regrowth or recontamination. One such philosophical difference is that the European water treatment community does not see the maintenance of a disinfectant residual to the end of the distribution system as a necessary public health protection measure. Although there are some philosophical differences between the United States and Europe relating to the treatment of the distribution system and its operations, the United States has benefited from the European experience. The United States has continued to examine water treatment practices in Europe, particularly water-quality standards established by the World Health Organization (WHO). The need to disinfect water to kill pathogens to protect against acute illnesses, versus the formation of disinfection by-products and their chronic health effects is an example of this risk balance. The revisions also started to address the need to balance immediate (acute) risks versus long-term (chronic) risks. The revisions reflected improvements in analytical methods to detect contaminants at lower levels and improvements in automated monitoring used to evaluate treatment plant performance. The Safe Drinking Water Act (SDWA) became law in 1974, and was significantly revised in 19. Environmental Protection Agency (EPA) later assumed responsibility for this task when it was established in 1970. Public Health Service developed the first drinking-water regulations in the United States in 1914. At the point in which the United States began using chlorine to disinfect drinking water (1908), Europe was also using chlorine but exploring the possibility of employing ozone to treat drinking water. John Snow was credited with this finding. An outbreak of cholera in London was linked to a sewage-contaminated drinking water well in 1854. Water-treatment concepts underlying those used today were developed in Europe during the 1700s. The engineered processes usually mimic or build on natural processes. Some of these occur in the natural environment, whereas others occur in engineered and constructed water treatment plants. The goal of water treatment, usually from surface sources such as lakes, reservoirs, or rivers, is to remove contaminants and organisms through a combination of biological, chemical, and physical processes to make it safe for drinking.
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