Not one drop of the water we consume every day is comprised exclusively of hydrogen and oxygen molecules. It contains some amount of minerals, impurities, microorganisms and other contaminants. 的se substances may be present in only trace amounts, and don’t necessarily have negative health effects.
美国nited States enjoys one of the best supplies of drinking water in the world. 然而, while tap water that meets federal and state standards is generally safe to drink, threats to drinking water are increasing. Actual incidences of drinking water contamination are rare, and typically do not occur at levels likely to pose health concerns. Nevertheless, a wide variety of issues have the potential to contaminate drinking water. 同样的, drinking water that is not properly treated or disinfected, or that travels through an improperly maintained distribution system, 也可能对健康造成威胁.
美国.S. Environmental Protection Agency (EPA) 安全饮用水法 requires municipalities to test water supplies once, 两次, 或者一年几次, depending on the potential contaminants and the size of the population served. Municipalities don’t continuously monitor the water pipes that transport water to homes. Water that leaves the treatment facility can become contaminated by the time it shows up at your tap.
Water suppliers are required by law to promptly inform their customers if the water has become contaminated by something that can cause immediate illness. Water suppliers have 24 hours to inform their customers of violations of EPA饮用水标准 “that have the potential to have serious adverse effects on human health as a result of short-term exposure.”