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Definitions and Terms

Aluminum: the most abundant metal in the earth’s crust. Occurs only in combination with other elements such as oxygen, silicon, and fluorine.

Major Use: aluminum compounds have many different uses (e.g., as alums in water-treatment and alumina in abrasives and furnace linings). They are also found in consumer products such as antacids, astringents, buffered aspirin, food additives, and antiperspirants.

Potential Health Effects: usually not harmful, except in high levels. Workers, who breathe large amounts of aluminum dusts, can have lung problems, such as coughing or abnormal chest X-rays. For more information about aluminum visit the ToxFAQ page about aluminum at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

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Arsenic: an inorganic crystalline element that is brittle, metallic steel-gray and poisonous; occurs naturally in the environment

Major Use: a naturally occurring element, also used in insecticides and weed killers

Other Uses: semiconductor manufacturing, petroleum refining, wood preservatives and animal feed additives

Potential Health Effects: skin damage; circulatory system problems; increased risk of cancer. For more information about arsenic visit the ToxFAQ page about arsenic at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Web site on basic information for Arsenic in Drinking Water.

Treatment Method: there are several types of point-of-use, in home filters that can be used to remove arsenic from drinking water, which use methods such as reverse osmosis, ultra-filtration, and ion exchange. Distilling the water can also be used to remove arsenic. For more information about these removal technologies, contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk-management. Boiling water will not remove arsenic and could slightly increase the concentration of arsenic in your water if you continue boiling and lose a large amount of water as steam. Chlorine (bleach) disinfection will also not remove arsenic.

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Barium: an inorganic metallic element that is malleable, silver-white, toxic and occurs only in combination with other chemicals

Major Use: used by the oil and gas industries to make drilling muds

Other Uses: used to make paint, bricks, ceramics, glass, and rubber

Potential Health Effects: short-term: Gastrointestinal disturbances and muscular weakness. Long-term: High blood pressure. For more information about barium visit the ToxFAQ page about barium at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Groundwater and Drinking Water Web page on Consumer Fact sheet on: Barium.

Treatment Method: ion exchange, reverse osmosis, lime softening, and electrodialysis are treatment methods approved by USEPA.

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Cadmium: (total) is a naturally occurring metal that is found in rocks and soil, typically in association with zinc ores

Major Uses: batteries, pigments, metal coatings, and plastics

Potential Health Effects: known human carcinogen because it causes lung cancer. The kidney is generally considered to be the most sensitive target for cadmium toxicity following exposure in food or water. Other systems affected by cadmium in humans include the gastrointestinal tract, respiratory tract and cardiovascular system. For more information about cadmium visit the ToxFAQ page about cadmium at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Groundwater and Drinking Water Web page on Consumer Fact sheet on: Cadmium.

Treatment Method: water treatment technologies certified by NSF for reduction of this contaminant are reverse osmosis or distillation. If you want to know more about these, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Calcium: (calcium hypochlorite) is a white solid that readily decomposes in water releasing oxygen and chlorine. It also has a strong chlorine odor. The compound occurs naturally in the environment.

Major Uses: used primarily as bleaching agents or disinfectants. It is a component of commercial bleaches, cleaning solutions, and disinfectants for drinking water and waste water purification systems and swimming pools.

Potential Health Effects: low calcium intake can be related to hypertension and cardiovascular disorders. It is responsible for water hardness. For more information about calcium visit the ToxFAQ page about calcium at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

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Chloride: naturally occurring salts

Sources: natural deposits. Its presence in large amounts may be due to natural processes such as the passage of water through natural salt formations in the earth or it may be an indication of pollution from sea water intrusion, industrial or domestic waste or de-icing operations.

Potential Health Effects: chloride concentrations in drinking water may be important to people on low-salt diets. Most people will detect a salty taste in water containing more than 250 mg/l of chloride.

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Copper: a common metallic element that is malleable, ductile, reddish-brown and is one of the best conductors of heat and electricity

Major Use: commonly used to make coins, electrical wiring, and household plumbing materials.

Other Uses: copper compounds are also used as agricultural pesticides and to control algae in lakes and reservoirs.

Potential Health Effects: copper is an essential nutrient, required by the body in very small amounts. However, the USEPA has found copper to potentially cause the following health effects when people are exposed to it at levels above the Action Level for relatively short periods of time: stomach and intestinal distress, liver and kidney damage, and anemia. Persons with Wilson's disease may be more sensitive than others to the effects of copper contamination. For more information about copper, see the ToxFAQ page about copper at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Groundwater and Drinking Water Web page on Consumer Fact sheet on: Copper.

Treatment Method: copper can be removed from water successfully by using treatment processes such as reverse osmosis and distillation at each separate faucet. To be effective, these treatment options require careful maintenance and testing. Contact your local health department for recommended procedures. Water can also be treated with a neutralizing filter. If you want to know more about these filters, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Fluoride: an inorganic, nonmetallic halogen element that is isolated as a pale, yellowish, flammable, toxic and diatomic gas

Major Use: water additive that promotes strong teeth

Other Uses: metallurgy and pesticides

Potential Health Effects: bone disease (pain and tenderness of the bones); Children may get mottled teeth. For more information about fluoride see the ToxFAQ for fluoride and related compounds at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

Treatment Method: water treatment technologies certified by NSF for reduction of this contaminant are reverse osmosis or distillation. If you want to know more about these, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Hardness: the measurement of all dissolved solid materials suspended in water. "Hard water" is a type of water that has high mineral content.

Sources: predominantly caused by the existence of the minerals calcium and magnesium in ground and surface water. These minerals come from sedimentary rock such as limestone that dissolves in our water. Hardness may range from zero to hundred of parts per million, depending on the origin of the water or the treatment to which the water has been subjected.

Potential Health Effects: hard water is not a health hazard. The World Health Organization said that there does not appear to be any convincing evidence that water hardness causes adverse health effects in humans. http://www.who.int/water_sanitation_health/dwq/chemicals/hardness.pdf. The National Research Council (National Academy of Sciences) recommends that further studies should be conducted on the correlation between hard water and lower cardiovascular disease mortality http://www.water-research.net/hardness.htm

Treatment Method: a water treatment technology certified by NSF for reduction of this contaminant is cation exchange softener. If you want to know more about this, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Iron: naturally occurring metal

Sources: natural deposits

Potential Health Effects: staining of laundry, plumbing and appliances. High iron concentrates make drinking water look and taste undesirable but will not hurt most people.

Treatment Method: a water treatment technology certified by NSF for reduction of this contaminant is adsorption (i.e. carbon/charcoal). If you want to know more about this, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Lead: a naturally occurring bluish-gray metal found in small amounts in the earth's crust

Major Uses: used in the production of batteries, ammunition, metal products (solder and pipes), and devices to shield X-rays

Potential Health Effects: lead is a poison whose effects are cumulative. Drinking water should not exceed 20 ppb. When groundwater contains a higher level, it may indicate contamination from the discharges of smelting or mining operations, or leachate from municipal sewage sludge fertilizer. For more information about lead visit the ToxFAQ page about lead at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Groundwater and Drinking Water Web page on Consumer Fact sheet on: Lead.

Treatment Method: first, try to identify and remove the lead source. If it is not possible or cost-effective to remove the lead source, flush the water system before using the water for drinking or cooking. Or consider water treatment methods such as reverse osmosis, distillation, and carbon filters specially designed to remove lead. Typically these methods are used to treat water at only one faucet. Contact your local health department for recommended procedures. If you want to know more about these filters, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Magnesium: a commonly used metals and one of the most abundant element in the earth's surface.

Sources: naturally occurring from soil and rocks.

Potential Health Effects: a common mineral that makes water "hard." Hard water is not a health hazard. In fact, the National Research Council (National Academy of Sciences) states that hard drinking water generally contributes a small amount toward total magnesium human dietary needs.

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Manganese: naturally occurring metal found in many types of rocks

Major Uses: common organic manganese compounds include pesticides, such as maneb or mancozeb, and methylcyclopentadienyl manganese tricarbonyl (MMT), a fuel additive in some gasoline.

Potential Health Effects: objectionable taste and may stain plumbing and laundry. For more information about manganese visit the ToxFAQ page about manganese at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

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Mercury: a naturally occurring metal which has several forms

Major Uses: metallic mercury is used to produce chlorine gas and caustic soda, and is also used in thermometers, dental fillings, and batteries.

Potential Health Effects: can permanently damage the brain, kidneys, and developing fetus. Effects on brain functioning may result in irritability, shyness, tremors, changes in vision or hearing, and memory problems. For more information about mercury visit the ToxFAQ page about mercury at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

Treatment Method: water treatment technologies certified by NSF for reduction of this contaminant are reverse osmosis, distillation or adsorption (i.e. carbon/charcoal). If you want to know more about these, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Nitrate: nitrogen-oxygen chemical units which combines with various organic and inorganic compounds

Major Use: fertilizer

Other Uses: in veterinary medicine and explosives

Potential Health Effects: short-term: Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. This is a very serious condition for infants up to six month of age. Long-term: Diuresis, increased starchy deposits and hemorrhaging of the spleen. For more information about nitrate see the nitrate/nitrite toxicity report at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

If you have nitrate in the mid-range (5-10 ppm): when levels of nitrate exceed 4-5 ppm this may indicate that a source of nitrogen is affecting your water quality. Because this could increase, it is important to carry out regular testing to ensure that your water contains levels that are acceptable for public drinking water supply. You may also want to look for sources of nitrogen that could affect your drinking water supply to determine if they can be managed to prevent pollution.

Treatment Method: nitrate may be successfully removed from water using treatment processes such as ion exchange, distillation, and reverse osmosis. Contact your local health department for recommended procedures. For more information on treatment systems, contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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pH: is a unit used to describe the acidity or alkalinity of water. Most drinking water is in the range of pH 6.5 to 8.5. pH 7 is neutral. Water above pH 7 is considered alkaline (basic), and below pH 7 is considered acidic. Rainwater is more acidic than groundwater.

If you have pH below 7: due to acid rain in parts of Hawaii, many water catchment systems, particularly those in the Volcano area, have pH readings that are lower than 5.5. The more acidic the water, the more prone to corrosion the system is. You can lessen the acidity of your catchment tank water by using a concrete water tank or by adding bicarbonate of soda to the tank.

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Selenium: a metal found in natural deposits as ores containing other elements

Major Uses: in electronic and photocopier components

Other Uses: used in glass, pigments, rubber, metal alloys, textiles, petroleum, medical therapeutic agents, and photographic emulsions

Potential Health Effects: exposure to high levels of selenium for a short period of time may result in hair and fingernail changes; damage to the peripheral nervous system; fatigue and irritability. Long-term: Selenium has the potential to cause the following effects from a lifetime exposure at levels above the MCL: hair and fingernail loss; damage to kidney and liver tissue, and the nervous and circulatory systems. For more information about selenium visit the ToxFAQ page about selenium at the Web site maintained by the Agency for Toxic Substances and Disease Registry, or the Environmental Protection Agency's Groundwater and Drinking Water Web page on Consumer Fact sheet on: Selenium.

Treatment Method: water treatment technologies certified by NSF for reduction of this contaminant are reverse osmosis or distillation. If you want to know more about these, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.

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Silver: a naturally occurring element. It is found in the environment combined with other elements such as sulfide, chloride, and nitrate.

Major Uses: processing of ores, cement manufacture, and the burning of fossil fuel may release silver into the air. It may be released into water from photographic processing.

Potential Health Effects: exposure to high levels of silver for a long period of time may result in a condition called arygria, a blue-gray discoloration of the skin and other body tissues. Can also result in breathing problems, lung and throat irritation, and stomach pains if exposed to high levels of silver in the air. Skin contact with silver can cause mild allergic reactions such as rash, swelling, and inflammation in some people. For more information about silver visit the ToxFAQ page about silver at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

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Sulfate: a substance that occurs naturally in drinking water

Sources: erosion of naturally occurring mineral deposits like Epsom salt, Glauber's salt or gypsum or the result of municipal or industrial discharges.

Potential Health Effects: can have gastrointestinal irritation and laxative effects in some individuals. Can give water a bitter or astringent taste. High sulfate levels may also corrode plumbing, particularly copper piping. For more information about sulfate visit the Environmental Protection Agency's Web site on Sulfate in Drinking Water.

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Turbidity: the measure of water clarity

Sources: soil runoff

Potential Health Effects: has no health effects but can interfere with disinfections and provide a medium for microbial growth. It may indicate the presence of microbes.

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Uranium: naturally occurring radioactive metal that occurs in low concentrations in nature. It is present in certain types of soils and rocks, especially granites.

Sources: erosion of natural deposits

Potential Health Effects: increased risk of cancer, kidney toxicity. Studies show that elevated levels of uranium in drinking water can increase a person’s risk of kidney damage. For more information about uranium visit the ToxFAQ page about uranium at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

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Total Dissolved Solids (TDS): the measurement of all dissolved solid materials suspended in water

Sources: erosion of naturally occurring mineral deposits

Potential Health Effects: gastrointestinal irritation in some individuals

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Zinc: naturally occurring metal

Sources: found naturally in many rock-forming minerals. Because of its use in the vulcanization of rubber, it is generally found at higher levels near highways. It also may be present in industrial discharges.

Potential Health Effects: leaves a metallic taste to water. Zinc toxicosis is not a common problem, but zinc poisoning in humans (e.g., from acid foods or beverages stored in galvanized containers) and animals (e.g., from ingesting or exposure to galvanized metal objects, certain paints and fertilizers, zinc-containing coins, etc.) has been documented. For more information about zinc visit the ToxFAQ page about zinc at the Web site maintained by the Agency for Toxic Substances and Disease Registry.

Treatment Method: a water treatment technology certified by NSF for reduction of this contaminant is adsorption (i.e. carbon/charcoal). If you want to know more about this, please contact NSF International, an organization for public health and safety through standards development, product certification, education, and risk management.