Coliforms are bacteria that are naturally present in the environment and used as an indicator that other, potentially harmful, bacteria may be present. Coliforms found in more samples than allowed is a warning of potential problems.

Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5

Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. Approximately 90 percent of industrial arsenic in the U.S. is currently used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps, and semi-conductors. Agricultural applications, mining, and smelting also contribute to arsenic releases in the environment.

Skin damage or problems with circulatory systems, and may have increased risk of getting cancer

Nitrates and nitrites are nitrogen-oxygen chemical units which combine with various organic and inorganic compounds. The greatest use of nitrates is as a fertilizer. Once taken into the body, nitrates are converted to nitrites.

Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome.

Trihalomethanes occur when naturally-occurring organic and inorganic materials in the water react with the disinfectants, chlorine and chloramine.

Liver, kidney or central nervous system problems; increased risk of cancer

Di(2-ethylhexyl) phthalate is the most commonly used of a group of related chemicals called phthalates or phthalic acid esters. The greatest use of di(2-ethylhexyl) phthalate is as a plasticizer for polyvinylchloride (PVC) and other polymers including rubber, cellulose and styrene. A number of packaging materials and tubings used in the production of foods and beverages are polyvinylchloride contaminated with phthalic aced esters, primarily di(2-ethylhexyl) phthalate.

Reproductive difficulties; liver problems; increased risk of cancer

Tetrachloroethylene is a colorless organic liquid with a mild, chloroform-like odor. The greatest use of tetrachloroethylene is in the textile industry, and as a component of aerosol dry-cleaning products.

Liver problems; increased risk of cancer

Haloacetic acids occur when naturally-occurring organic and inorganic materials in the water react with the disinfectants, chlorine and chloramine.

Increased risk of cancer

Antimony is a metal found in natural deposits such as ores containing other elements. The most widely used antimony compound is antimony trioxide, used as a flame retardant. It is also found in batteries, pigments, and ceramics/glass.

Increase in blood cholesterol; decrease in blood sugar

Trichloroethylene, a volatile organic chemical, is a colorless or blue liquid with a chloroform-like odor. Trichloroethylene is primarily used to remove grease from fabricated metal parts and in the production of some textiles.

Liver problems; increased risk of cancer

Pentachlorophenol is a white organic solid with needle-like crystals and a phenolic odor. The greatest use of pentachlorophenol is as a wood preservative (fungicide). Though once widely used as an herbicide, it was banned in 1987 for these and other uses, as well as for any over-the-counter sales.

Liver or kidney problems; increased cancer risk

Ethylbenzene is a colorless organic liquid with a sweet, gasoline-like odor. The greatest use – more than 99 percent – of ethylbenzene is to make styrene, another organic liquid used as a building block for many plastics. It is also used as a solvent for coatings, and in the making of rubber and plastic wrap.

Liver or kidneys problems

Toluene is an organic liquid with a sweet, benzene-like odor. The largest chemical use for toluene is to make benzene and urethane.

Nervous system, kidney, or liver problems

Cadmium is a metal found in natural deposits such as ores containing other elements. Cadmium is used primarily for metal plating and coating operations, including transportation equipment, machinery and baking enamels, photography, and television phosphors. It is also used in nickel-cadmium solar batteries and pigments.

Kidney damage

Lead is a toxic metal that was used for many years in products found in and around homes. Even at low levels, lead may cause a range of health effects including behavioral problems and learning disabilities. Children six years old and under are most at risk because this is when the brain is developing. The primary source of lead exposure for most children is lead-based paint in older homes. Lead in drinking water can add to that exposure.

Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities

para-Dichlorobenzene is an organic solid of white crystals with a mothball-like odor. p-Dichlorobenzene is used mainly as an insecticidal fumigant against clothes moths and as a deodorant for garbage and restrooms. It is also used as an insecticide and fungicide on crops, and in the manufacture of other organic chemicals and in plastics, dyes, and pharmaceuticals.

Anemia; liver, kidney or spleen damage; changes in blood

Benzene, a volatile organic chemical, is a clear, colorless aromatic liquid. It is highly flammable. It is formed through natural processes, such as volcanoes and forest fires. It is also formed from industrial processes. Benzene is also a natural part of crude oil, gasoline and cigarette smoke. The greatest use of benzene is as a building block for making plastics, rubber, resins and synthetic fabrics like nylon and polyester. Other uses include: as a solvent in printing, paints, dry cleaning, etc.

Anemia; decrease in blood platelets; increased risk of cancer

1,2-Dichloroethane is a colorless, oily, organic liquid with a sweet, chloroform-like odor. The greatest use of 1,2-dichloroethane is in making chemicals involved in plastics, rubber and synthetic textile fibers. Other uses include: as a solvent for resins and fats, photography, photocopying, cosmetics, drugs, and as a fumigant for grains and orchards.

Increased risk of cancer

Vinyl chloride is a colorless organic gas with a sweet odor. Vinyl chloride is used in the manufacture of numerous products in building construction, automotive industry, electrical wire insulation and cables, piping, industrial and household equipment, medical supplies, and is depended upon heavily by the rubber, paper, and glass industries.

Increased risk of cancer

Carbon tetrachloride is a clear heavy organic liquid with a sweet aromatic odor similar to chloroform. Most carbon tetrachloride is used to make chlorofluorocarbon propellants and refrigerants, though this has been declining steadily. It has also been used as a dry cleaning agent and fire extinguisher; in making nylons; as a solvent for rubber cement, soaps, insecticides, etc.

Liver problems; increased risk of cancer

1,1,1-Trichloroethane is an organic liquid with a chloroform-like odor. It is largely used as a solvent removing grease from machined metal products, in textile processing and dyeing and in aerosols.

Liver, nervous system, or circulatory problems

Dichloromethane, also known as DCM and methylene chloride, is a volatile organic and colorless liquid chemical with a sweet, pleasant odor like chloroform. The greatest use of DCM is as a paint remover. Other uses include: solvent and cleaning agent in chemical manufacture, textiles, electronics, metals and plastics, pesticides industries; blowing and cleaning agent in the urethane foam industry; fumigant for strawberries and grains, and as degreener for citrus fruits; in pharmaceuticals and as an anesthetic; in extraction of caffeine, cocoa, fats, spices and beer hops; as a heat transfer agent in refrigeration products.

Liver problems; increased risk of cancer

1,1-Dichloroethylene is an organic liquid with a mild, sweet, chloroform-like odor. Virtually all 1,1-dichloroethylene is used in making adhesives, synthetic fibers, refrigerants, food packaging and coating resins such as the saran types.

Liver problems

The gaseous or liquid form of chlorine (CL2) is a water additive used by municipal water systems to control microbes. It is relatively inexpensive and has the lowest production and operating costs and longest history for large continuous disinfection operations. Chlorine is a powerful oxidant.

Eye/nose irritation; stomach discomfort

Styrene is an oily organic liquid with an aromatic, almost floral odor. Initially, styrene was used primarily in the synthetic rubber industry, but it is currently used as a building block for polymers in making plastics, resins, coatings, and paints.

Liver, kidney, or circulatory system problems

Chlorobenzene is a colorless organic liquid with a faint, almond-like odor. Chlorobenzene is used in the manufacture of other organic chemicals, dyestuffs and insecticides. It is also used a solvent for adhesives, drugs, rubber, paints and dry cleaning, and as a fiber-swelling agents in textile processing.

Liver or kidney problems

1,1,2-Trichloroethane, a volatile organic chemical is a liquid with a chloroform-like odor. 1,1,2-Trichloroethane is used to make vinylidene chloride which is in turn used to make synthetic fibers and plastic wraps. It is also used in adhesives, production of Teflon tubing, in lacquer and coating formulations, and as a solvent for fats and oils.

Liver, kidney, or immune system problems

1,2-Dichloropropane is a colorless flammable liquid with a chloroform-like odor. It does not occur naturally in the environment. It is used to make other organic chemicals. It is also used in making lead free gasoline, paper coating, soil fumigant for nematodes, and insecticide for stored grain.

Increased risk of cancer

ortho-Dichlorobenzene is a colorless organic liquid with a pleasant, aromatic odor. The greatest use of o-dichlorobenzene is as a chemical intermediate for making agricultural chemicals, primarily herbicides. Other present and past uses include: solvent for waxes, gums, resins, wood preservatives, paints; insecticide for termites and borers; in making dyes; as a coolant, deodorizer, degreaser.

Liver, kidney, or circulatory system problems

cis-1,2-Dichloroethylene is an odorless organic liquid that has two slightly different forms, a cis form and a trans form. Both the cis and trans forms – usually as a mixture – are used as a solvent for waxes and resins; in the extraction of rubber; as a refrigerant; in the manufacture of pharmaceuticals and artificial pearls; in the extraction of oils and fats from fish and meat; and in making other organics.

Liver problems

1,2-Dibromo-3-chloropropane, or DBCP, is a dense yellow organic liquid with a pungent odor. It is used primarily as an unclassified nematocide for soil fumigation of cucumbers, summer squash, cabbage, cauliflower, carrots, snap beans, okra, aster, shasta daisy, lawn grasses and ornamental shrubs.

Reproductive difficulties; increased risk of cancer

trans-1,2-Dichloroethylene is an odorless organic liquid that has two slightly different forms, a cis form and a trans form. Both the cis and trans forms — usually as a mixture — are used as a solvent for waxes and resins; in the extraction of rubber; as a refrigerant; in the manufacture of pharmaceuticals and artificial pearls; in the extraction of oils and fats from fish and meat; and in making other organics.

Liver problems

Ethylene bromide, also known as EDB, and 1,2-Dibromoethane, is a colorless, heavy synthetic organic liquid with a mildly sweet chloroform-like odor. Ethylene dibromide is mainly used in an anti-knock gasoline mixtures, particularly aviation fuel.

Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancer

Beryllium is an inorganic metallic element in the periodic table. Because it is an element, it does not degrade nor can it be destroyed. Compounds of beryllium are either white or colorless and do not have a particular smell. The greatest use of beryllium is in making metal alloys for nuclear reactors and the aerospace industry. Other uses are as an alloy and oxide in electrical equipment and microwave ovens.

Intestinal lesions

Fluoride compounds are salts that form when the element, fluorine, combines with minerals in soil or rocks. Many communities add fluoride to their drinking water to promote dental health.

Bone disease (pain and tenderness of the bones); Children may get mottled teeth

Selenium is a metal found in natural deposits such as ores containing other elements. The greatest use of selenium compounds is in electronic and photocopier components, but they are also widely used in glass, pigments, rubber, metal alloys, textiles, petroleum, medical therapeutic agents, and photographic emulsions.

Hair or fingernail loss; numbness in fingers or toes; circulatory problems

Chromium is an odorless and tasteless metallic element. Chromium is found naturally in rocks, plants, soil and volcanic dust, humans and animals. The most common forms of chromium that occur in natural waters in the environment are trivalent chromium (chromium-3), and hexavalent chromium (chromium-6). Chromium-3 is an essential human dietary element and occurs naturally in many vegetables, fruits, meats, grains and yeast. Chromium-6 occurs naturally in the environment from the erosion of natural chromium deposits but it can also be produced by industrial processes. There are demonstrated instances of chromium being released to the environment by leakage, poor storage, or inadequate industrial waste disposal practices.

Allergic dermatitis

Thallium is a metal found in natural deposits such as ores containing other elements. The greatest use of thallium is in specialized electronic research equipment.

Hair loss; changes in blood; kidney, intestine, or liver problems

Mercury is a liquid metal found in natural deposits such as ores containing other elements. Electrical products such as dry-cell batteries, fluorescent light bulbs, switches, and other control equipment account for 50 percent of mercury used.

Kidney damage

Barium is a lustrous, machinable metal which exists in nature only in ores containing mixtures of elements. It is used in making a wide variety of electronic components, in metal alloys, bleaches, dyes, fireworks, ceramics and glass. In particular, it is used in well drilling operations where it is directly released into the ground.

Increase in blood pressure