Quick Answer
In the United States, the Environmental Protection Agency (EPA) regulates water purification under the Safe Drinking Water Act, which sets standards for treatment and disinfection. The EPA also sets standards for water quality under the Clean Water Act. State and local regulations may also apply.
Federal Regulations
The Safe Drinking Water Act requires water treatment facilities to meet specific standards for treatment, including coagulation, sedimentation, filtration, and disinfection. The Act also sets standards for residual disinfectants, such as chlorine and ozone, and for inorganic and organic contaminants. For example, the maximum contaminant level (MCL) for total trihalomethanes (TTHMs) is 80 micrograms per liter.
State and Local Regulations
Some states and local governments have their own regulations for water purification, which may be more stringent than federal standards. For example, California requires water treatment facilities to meet standards for perchlorates, which are contaminants associated with military and industrial activities. States may also have specific regulations for recreational water contact, such as swimming pools and water parks.
Techniques and Technologies
Water purification techniques and technologies can vary widely, depending on the source and quality of the water. Some common methods include distillation, reverse osmosis, and activated carbon filtration. For example, a home water filter system using activated carbon can remove chlorine, lead, and volatile organic compounds (VOCs) from drinking water. In some cases, ultraviolet (UV) light disinfection may be used to kill bacteria and viruses.
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