What Is a Water Purification Plant?

Have you ever wondered how water that falls as rain or comes from the ground is purified and delivered to your home or business? In the United States, it all happens at the tens of thousands of public water purification plants where raw water is treated to remove impurities before being piped to end users through an extensive distribution network. Most water is purified for human consumption, but water can be treated for a variety of other uses. The purification technology used depends on the specific treatment requirements, the raw water source and the contaminants present.

Importance of Purified Water

Water is found in nature, but pure water is not. Contaminants, such as minerals, toxic metals and suspended organic particles, enter the water through contact with air, rain and runoff. Purified water is necessary to sustain life, food production and recreational water use, and to prevent life-threatening illnesses, such as acute diarrhea, parasitic diseases and cholera. Water also must be cleaned to meet the requirements of medical, pharmacological, chemical and industrial applications for these business sectors to survive.

Standards and Methods

The standards for drinking water quality are set by national regulations, including those set forth under the Safe Drinking Water Act in the United States, and by international standards that set safe contaminant concentration levels. Water purification can effectively remove a wide range of contaminants, including aquatic pathogens, heavy metals, toxic chemicals and pesticides. A number of elective treatment processes also address drinking water aesthetics by eliminating objectionable smells and tastes, and improving appearance.

Treating Raw Water

Once raw water from surface water and groundwater supplies enters the purification plant, mechanical and chemical treatment processes are used, depending on the scale of the plant, contaminants present and intended use of the finished water. According to the U.S. Environmental Protection Agency (EPA), three individual treatment processes generally are included in a "treatment train," or series of processes that are customized and applied in sequence: flocculation/sedimentation, filtration and disinfection.

Types of Treatment

Flocculation/sedimentation refers to the process that combines or coagulates small particles into larger particles through flocculation, according to the EPA. The particles settle out as sediment and are removed from the water supply. Filtration using a porous media removes all remaining particles from the water. The process clarifies water and enhances the effectiveness of disinfection. Using chlorination or ozonation, disinfection ensures that potentially harmful organisms and pathogenic bacteria are killed before water is distributed to homes and businesses.

Jardine Water Purification Plant

The James W. Jardine Water Purification Plant, located next to Navy Pier in Chicago, Illinois is the largest water purification plant in the world. Drawing raw water from two offshore cribs in Lake Michigan, the plant pipes nearly one billion gallons of water a day to Chicago area consumers. In 1955, the American Society of Civil Engineers recognized the Metropolitan Sanitary District of Greater Chicago as one of the seven engineering wonders of the United States, according to the Eastland Memorial Society.

Whitney Water Treatment Plant

In 2005, the South Central Connecticut Regional Water Authority completed the Lake Whitney Water Treatment Plant, which replaces an old slow-sand filter facility with a plant that uses two levels of advanced protection, or barriers. Level one protections involve watershed protection to prevent contamination of source water through measures, such as water quality monitoring, hazardous waste disposal education and open space preservation. Level two protections use advanced water treatment technologies in the areas of solids removal, filtration and disinfection.

Purfied Water in Other Countries

Worldwide, the lack of access to water treated at purification plants--or water treated by any means for that matter--presents one of the largest public health challenges today. Some 884 million people lack access to safe drinking water, and about 6,000 people a day die from water-related illnesses, according to Water For People. Many organizations are working to help developing nations identify sustainable clean water solutions, including the drilling of wells. To learn more about safe water issues or find ways to help those in need, visit the EPA, World Water Day and Peace Corps websites or of the sites listed in the Resources section below.

References

• EPA
• Jardine water purification plant information
• Lake Whitney Water Treatment Plant

Resources

• United Nations Human Development Reports
• Water.org
• Charitywater.org