Contaminants in water include biological contaminants such as microorganisms (pathogenic or not), algae, protozoa, etc; organic contaminants such as chemicals, biocides, insecticides, herbicides and residues of organic matter; inorganic contaminants such as some inorganic chemical compounds, fertilizers, and elements (some of them naturally present in water as Calcium and Magnesium that introduce hardness in water), heavy metals such as Lead and Mercury among others; and radioactive substances, of particular concern in some parts of the United States.
As can be inferred, surface water is normally more contaminated than ground water as result of human and industrial activities. However, ground water can in some cases get contaminated through infiltration from septic systems, dumps, landfills and other sources, including industrial waste. In some instances, ground water could have radioactive substances coming from the rock beds in contact with this water. Well supplies normally yield cool and uncontaminated water of uniform quality throughout the year that is easily processed for municipal use, requiring usually removal of gases and some minerals that could be present.
Most of the cities and municipalities have water treatment plants in order to make water potable, and comply with the U.S. Environmental Protection Agency (EPA) regulations (consult http:/www.epa.gov/safewater/mcl.html) and local standards for drinking water. They must perform regular sampling and analysis to check water quality and suitability of the treatment methods used, reducing the concern from real estate owners regarding health and other aspects that could affect property value. Municipal water treatment reduces microorganisms and pathogens to accepted levels, also reduce hardness in water and the presence of some chemical substances that could be present.
Of more concern is water coming from private water wells and owners must exert periodical control of its quality and condition. It is estimated that about 15% of Americans rely on their own private water supply. Private well water is not regulated by the EPA but recommendations for owners of private wells have been presented (http:/www.epa.gov/safewater/privatewells/index2.html). Unlike public drinking water systems serving a large population, private well owners do not have experts regularly checking the water’s source. These households must take special precautions to ensure the protection and maintenance of their drinking water supplies. This could be a concern for home buyers.
Drinking water is usually treated with chlorine compounds in order to inactivate microorganisms and render water potable. Other compounds can also be used for this purpose. Fluoridation is usually also accomplished during the treatment process to supply Fluor (F) to drinking water.
Hardness is produced by multivalent metallic cations in water such as Calcium (Ca) and Magnesium (Mg) that are more common in areas having extensive geological formations of limestone. Although satisfactory for human consumption, Calcium and Magnesium can precipitate soap, reducing its cleansing action and causing scale in pipes, water heaters, boilers and heat exchange equipment that could result in corrosion, internal pipe diameter reduction and waste of energy by reducing the heat transfer rate. Waters with less than 50 milligrams/liter (mg/L) of hardness are considered soft, up to 150 mg/L moderately hard and in excess of 300 mg/L very hard. Hardness can be removed by various methods, including the lime-soda ash method, ion exchange, reverse osmosis and distillation.
Water treatment also regulates important water parameters such as pH, acidity, alkalinity, color, taste and odor, turbidity, Iron (Fe) and Manganese (Mn), suspended and dissolved solids among other substances, making water chemically and microbiologically safe for human consumption and other domestic uses.
Radionuclides in Water
Surface waters are little affected by radionuclides, however, well waters in some parts of the U.S. can present this problem as indicated previously. Of principal concern are isotopes of Radium (Ra) 226, 228 and 224; alpha particle emitters; beta-photon emitters; Uranium (U) 234, 235, 238 isotopes; and Polonium (Po), Strontium (Sr) and other radionuclides. Water can also contain dissolved Radon (Rn) gas originating from decay of Uranium and Thorium (Th).
Radionuclides in water could result in cancer and tumor development, depending on the quantity of water ingested; the level of radionuclides; and time of exposure. For more information about this topic consult the report: http://www.epa.gov/safewater/radionuclides/basicinformation.html.
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