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Common Water Contaminants Classified as Health Risks
How harmful contaminants make their way into your water
  • Water is the breeding ground for a large variety of organisms. These organisms gain entry into water through various sources, such as the natural environmentof the water source , surface drainage, and sewage.

  • Water is an ideal medium in which organisms can grow. Many of the organisms in water are harmless. In fact, they are extremely beneficial to man. Others have a mild nuisance value. And still others are a source of disease.

  • Tremendous strides have been made in the control of these diseases within recent years. Much of the credit goes to sanitary engineers for their careful, consistent control of public water supplies.

  • While there are a large and varied number of pathogens, no single contaminated water supply is apt to contain more than a few of the countless variety. It makes detection of pathogens extremely difficult in terms of a routine water analysis. Both speed and accuracy are essential to detecting contaminants.

  • To ensure protection from waterborne disease, the U.S. Environmental Protection Agency (US EPA) proposed that drinking water should be treated to reduce the risk of contracting an infection to no more than 1:10,000 per year.

  • Toxic chemical contaminants also pose heal th problems, such as: arsenic, chromium VI, fluoride, lead, nitrates, polychlorinated biphenyl compounds (PCBs ) , perchlorate , and inert radionuclides.

  • The amounts of these microorganisms and chemical substances allowed in public drinking water supplies are regulated by the US EPA to comply with the Safe Drinking Water Act.

  • Water supplies can contain dissolved organic chemicals that result from man-made activities, such as insecticides, pesticides, herbicides and the gasoline additive MTBE. Because they are present in water in extremely small amounts, their health effects are usually chronically, rather than acutely, toxic to humans and other life. Additional organic chemicals that can enter surface and groundwater through chemical spills are trichlorethylene, tetrachlorethylene (TCEs), polychlorinated biphenyls (PCBs), and dioxin. Many organic contaminants are likely to be carcinogenic (cancer-producing).

  • Disinfection by-products such as trihalomethanes (THMs) are dissolved organic contaminants. They are formed by the reaction of the chlorine used to disinfect water with humic and fulvic acids present from vegetation decay.

  • Even though found rarely in drinking water—and in much smaller quantities—certain inorganic chemicals can be toxic. Examples include: arsenic, nitrates, heavy metals, chromium (V I ) and hydrogen sulfide.

Water Impurities
  • As water percolates through the ground, it has ample opportunity to dissolve large amounts of earth minerals.

  • The further water travels underground, the higher amounts of dissolved minerals and impurities collect. The longer water has been underground the more dissolved minerals it will contain. Compared to surface water, water from wells will often have high concentrations of dissolved minerals.

  • Surface water runoff picks up impurities (pollutants) left from human, agriculture or industrial activities. These impurities may also be found in poorly constructed or deteriorating wells.

  • At any time, less than 1% of the world’s water is available for use in fresh water rivers, lakes, and underground reservoirs; the other 99% is working its way through the hydrologic cycle.

  • As increases in population, agriculture and industry raise the demand for water, we tap older water resources that have either traveled farther underground or collected underground for longer periods of time. In both cases, the water contains higher amounts of dissolved minerals.

  • The human impact on the hydrologic cycle can be seen by looking at what things we contribute to our water systems, such as human waste, pharmaceutical products, agricultural and gardening byproducts, manufacturing byproducts and industrial waste. We are contributing more impurities to our water systems than the soil can filter out. This leads to an increased concentration of impurities in the useable water.

  • Chlorine is placed into the water supply to attack and kill organic matter. Its great for delivering bacteria free water to your home, the downside is, you are comprised of organic matter too. Its up to you to remove it from your water source.

  • Chlorine causes dry, itchy, flaky skin, brittle hair, eye, lung and sinus irritation. It is readily absorbed through your skin, a great deal of your chlorine exposure happens in the shower. When heated, chlorine forms chloroform gas, leading to added irritation for allergy & Asthma sufferers.

  • Chlorine has very obvious affects on your health but studies show there are even greater concerns regarding your health. In recent studies, chlorine’s disinfection by products have been shown to be carcinogenic

  • Chloramine, like chlorine, is placed into the water supply to attack and kill organic matter. Its great for delivering bacteria free water to your home, the downside is, you are comprised of organic matter too. Its up to you to remove it from your water source.

  • It might sound strange but Chloramine is actually a compound of chlorine and ammonia (didn’t your mother tell you not to mix those two!). Chloramine is typically found in the southern US but is used in select systems throughout the US. Florida, Texas & California often use chloramine.
  • Chloramine is used in water sources where bacteria control is more difficult and/or water is distributed over a larger area. It does does not disperse in the water readily and remains in higher concentrations over a longer period of time. To find out if your system uses Chloramine, Email Us or contact your local Municipal Water Treatment center.

  • Chloramine causes dry, itchy, flaky skin, brittle hair, eye, lung and sinus irritation. It is readily absorbed through your skin, a great deal of your chlorine exposure happens in the shower. When heated, chlorine forms chloroform gas, leading to added irritation for allergy & Asthma sufferers.

  • Chloramine has very obvious affects on your health but studies show there are even greater concerns regarding your health. In recent studies, Chloramine disenfection by products have been shown to be carcinogenic

  • The presence of arsenic in nature is due mainly to natural deposits in the earth’s crust, usually in ancient rock formations.

  • Arsenic enters groundwater through erosion or from man-made sources such as preservation of wood, petroleum production, semiconductor manufacturing or due to its use as feed additive and herbicide. Lumber mills are no longer using arsenic for treated lumber.

  • Higher levels of arsenic tend to be found more in ground water sources than in surface water sources (i.e., lakes and rivers).

  • Arsenic is toxic to humans and the ingestion of as little as 100 milligrams (mg) can result in severe poisoning. The effects of the poison when ingested in small amounts, appear very slowly and include skin damage or problems with circulatory systems, and may increase the risk of getting cancer. (USEPA)

  • Water testing is necessary to detect the presence of arsenic because it is tasteless and colorless.

  • Compared to the rest of the United States, the western states have more water systems with high arsenic levels, although some systems in the Midwest and New England have high arsenic levels.

  • Prior to January 23, 2003 the MCL for as was 50 ppb. It is now 10 ppb. The EPA and CDC have set goals for Zero ppb levels, as studies now confirm, no level of Arsenic is acceptable.

  • Fluoride in water can be detrimental, although it may slow tooth decay, studies show that its ingestion has negative effects in other areas. As a result, not every Municipal Water Treatment center fluoridates their water and there are plans in motion to reduce or eliminate fluoride in Water Treatment Facilities that do add it to the water source. 41% of children, aged 12-15, now suffer from mild to severe Fluorosis, a medical condition caused by over-exposure to fluoride, up from 22% in 1987-1989.

  • Research has shown that a concentration of about one milligram per liter (ppm) of fluoride in drinking water reduces tooth decay. Many cities fluoridate the public water supply in concentrations of one ppm in order to reduce tooth decay.

  • When drinking water contains excessive fluoride, it causes “endemic dental fluorosis.” Sometimes called “Colorado Brown Stain,” it appears as a dark brown mottling or spotting of the teeth or causes them to become chalky white. Above four milligrams of fluoride per liter crippling skeletal fluorosis, a serious bone disorder, and osteopetrosis or brittle “marble” bones, can occur.

  • Lead is a metallic element that is toxic to humans. It tastes sweet.

  • Lead binds to soils and does not migrate to ground water. In water, it binds to sediments. It does not accumulate in fish. This is why it is seldom found in ground waters or natural waters in more than trace quantities.

  • Source waters that contain lead are an indication that intrusions from industrial, mine, or smelter wastes may have occurred.

  • Typically, source water contains less lead than the water at the “point-of-use.”

  • Studies indicate that nearly all the lead in users’ tap water does not come from the primary water source or from the municipal treatment plant, but is a result of corrosion of lead containing materials that contact water after leaving the treatment plant.

  • Lead can enter home drinking water by leaching from lead service connections, from lead solder used in copper piping, and from brass fixtures.

  • The human body can be damaged by ingested lead. Lead poisoning shows no symptoms. However, signs such as irritability, weight loss, vomiting, constipation, or stomach pain could occur. Infants and children may experience delays in physical or mental development. Children could show slight deficits in attention span and learning abilities. Adults may exhibit kidney problems or high blood pressure. (USEPA)

  • Damage to the brain, kidneys, and bone marrow can occur with lower exposures.

  • Coma and convulsions can also be associated with lower exposures of lead.

  • Lead can also damage a person’s nervous system and red blood cells.

  • Children are more at risk than adults when it comes to the dangers of ingesting lead. Children will absorb 30-75% of the lead they ingest while adults will absorb only 11%.

  • The most acute cases of lead poisoning can cause death.

  • Nitrates are formed naturally when nitrogen combines with oxygen or ozone. They have no visible color, taste, or odor.

  • Nitrates are also made in large amounts by plants and animals, and are released in smoke and industrial or automotive exhaust.

  • The presence of nitrates in a water supply indicates possible pollution of the water with animal wastes.

  • Nitrogen is essential for all living things, but high levels of nitrate in drinking water can be dangerous to health, especially for infants and pregnant women.

  • Nitrate in drinking water can be responsible for a temporary blood disorder in infants called methemoglobinemia (blue baby syndrome). In infants less than six months old, a condition exists in their digestive systems which allows for nitrate to be absorbed through the stomach and reacts with blood to reduce the oxygen carrying capacity of hemoglobin. Thus, the oxygen deficiency in the infant’s blood results in the “blue baby” syndrome. When the nitrate-contaminating source is removed, the effects are reversible. If nitrates are suspected, a water analysis should be obtained from a laboratory certified for such analyses.

  • Although extreme levels of nitrate can be associated with central nervous disorders in adults, nitrates and nitrites are rarely a problem in drinking water for humans older than six months of age.

  • Pesticides can be beneficial for the control of pests like weeds and insects, but every pesticide (including organic pesticides) has some level of toxicity to organisms that live in or drink water.

  • Many pesticides can also pose risks to people. Their health effect depends upon: how toxic the pesticides are, the amount of pesticide in the water, and how much exposure occurs on a daily basis. Even products that are low in toxicity can be hazardous with a high enough exposure.

  • Each pesticide may contain a combination of chemicals US EPA has determined that five groups of pesticides each have a common mechanism of toxicity and require cumulative risk assessments because exposure to these pesticide groups may pose potential risks to human health and the environment. The five groups are: the organophosphates, N-methyl carbamates, triazines, chloroacetanilides, and pyrethrins/pyrethroids.

  • Some pesticides, such as the organophosphates and carbamates, affect the nervous system. Others may irritate the skin or eyes. Some pesticides may be carcinogens. Others may affect the hormone, or endocrine, system in the body. ( US EPA & NPIC)

  • Herbicides are chemicals, such as Atrazine or Glyphosate, that are created to control weeds or other undesirable vegetation. The most frequent application of herbicides occurs in row-crop farming, where they are applied to maximize crop productivity by minimizing other vegetation. Other applications are made to lawns, parks, golf courses. They can be applied to water bodies to control aquatic weeds that interfere with agricultural, industrial or recreational uses.

  • Exposure to high levels of Atrazine for many years could lead to problems with the cardiovascular system or reproductive difficulties. Exposure to high levels of Glyphosate over many years could increase risks of kidney problems or reproductive difficulties. (USEPA)

Hydrogen Sulfide
  • Hydrogen sulfide is a colorless gas that has a strong odor of rotten eggs. It is a natural product of decaying organic matter. In residential settings Hydrogen sulfide most commonly results from decomposition in septic or sewer systems.

  • The primary uses of Hydrogen sulfide include the production of elemental sulfur and sulfuric acid, the manufacture of heavy water and other chemicals; in metallurgy; and as an analytical reagent. In agriculture, it is used as a disinfectant.

  • Occupational exposure to Hydrogen sulfide occurs primarily from its presence in petroleum, natural gas, soil, sewer gas and as a byproduct of chemical reactions, e.g., viscose rayon and certain leather tanning processes.

  • Hydrogen sulfide can cause chronic health effects in humans and because of its toxicity, adversely affects aquatic organisms.

  • It affects the central nervous system with symptoms such as dizziness, nausea, headache and more long-acting symptoms such as abrupt physical collapse or unconsciousness. Prolonged unconsciousness can lead to respiratory failure, hypoxia, and death. (USEPA)

Disinfectant by Products from Chlorine/Chloramine
  • Haloaecetic acids are a byproduct of a disinfection process used to control microbial contaminants in drinking water. They are formed when a disinfectant such as chlorine, reacts with naturally occurring organic matter in water.

  • The regulated haloacetic acids, known as HAA5, are: monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid.

  • Ingestion of Haloaecetic acids may cause an increased risk of cancer (USEPA

  • Trihalomethanes are a byproduct of a disinfection process used to control microbial contaminants in drinking water. They are formed when a disinfectant such as chlorine, reacts with naturally occurring organic and inorganic matter in water.

  • The trihalomethanes are a group of these four chemicals: chloroform, bromodichloromethane, dibromochloromethane, and bromoform .

  • Trihalomethanes volatile organic chemical can affect the liver, kidney, or central nervous system as well as cause an increased risk of cancer. (USEPA)

Radioactive Contaminants
  • Radioactive Contaminants are present in 25% of the United States Water Sources


  • Radium is a naturally-occurring radioactive metal. Radium is a radionuclide formed by the decay of uranium and thorium in the environment. It occurs at low levels in virtually all rock, soil, water, plants, and animals.

  • Radium emits several different kinds of radiation, in particular, alpha particles and gamma rays. Alpha particles are generally only harmful if emitted inside the body. However, both internal and external exposure to gamma radiation is harmful. Gamma rays can penetrate the body, so gamma emitters like radium can result in exposures even when the source is a distance away.

  • Long-term exposure to radium increases the risk of developing several diseases. Inhaled or ingested radium increases the risk of developing such diseases as lymphoma, bone cancer, and diseases that affect the formation of blood, such as leukemia and aplastic anemia. These effects usually take years to develop. External exposure to radium’s gamma radiation increases the risk of cancer to varying degrees in all tissues and organs.

  • The greatest health risk from radium is from exposure to its radioactive decay product radon. It is common in many soils and can collect in homes and other buildings. ( US EPA)


  • Uranium is a naturally-occurring element found at low levels of radiation found in virtually all rock, soil, and water. Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as uraninite in uranium-rich ores.

  • A person can be exposed to uranium by inhaling dust in air, or ingesting water and food.

  • Uranium does not absorb through the skin, and alpha particles released by uranium cannot penetrate the skin. Uranium that is outside the body is much less harmful than it would be if it where inhaled or swallowed.

  • When uranium gets inside the body it can lead to cancer or kidney damage, or both. ( USEPA)

Inert Radionuclides

  • A radionuclide is an atom with an unstable nucleus which, to become more stable, emits energy in the form of rays or high speed particles.  This is called ionizing radiation because it can create “ions” by displacing electrons in the body e.g. in the DNA, disrupting its function.  The three major types of ionizing radiation are: alpha particles, beta particles and gamma rays.

  • Approximately 80% of our exposure to radioactivity is natural and another 20% is from man-made sources. More frequent use of diagnostic imaging involving radiation (x-rays, CT scans) is increasing exposure from man-made sources.

  • We are exposed to naturally occurring radiation for example from radon gas emanating from rocks and soil, and cosmic radiation from space.  We also carry small amounts of potassium-40 in our bodies from the foods containing potassium.  Radiation may exist in drinking water from nuclides dissolved in the water from natural sources in the earth or occasionally from radiation releases from laboratories or nuclear power plants.

  • Ingestion of drinking water with high levels of radionuclides over many years may increase the risks of getting cancer. ( US EPA)

Chromium VI
  • There are 3 forms of chromium: Metallic chromium (Cr 0 ), trivalent Chromium (Cr 3+ ) and hexavalent Chromium (Cr 6+ ). The latter forms compounds of chromate and dichromate. It is possible, under the right chemical environment for chromium to convert to different forms.

  • Metallic elemental chromium (or chrome) does not occur naturally in the environment. It is used to make steel and other metal alloys and is produced from chrome bearing ore.

  • Trivalent chromium occurs naturally in the environment and can be found in rocks and soil. It can also be found in fruits, vegetables and meat. It is not considered a significant health risk.

  • Hexavalent chromium does not occur naturally in the environment. It is produced by certain chemical processes and is considered toxic. It is considered a health risk whether it contacts the skin, it is inhaled, or it is ingested. It can cause nausea, gastrointestinal distress, stomach ulcers, skin ulcers, allergic reactions, kidney and liver damage, reproductive problems, and lung and nasal cancer.

  • New scientific research suggests that a separate standard specifically for Chromium VI may be needed . In 2008 , the Department of Health and Human Service’s National Toxicology Program conducted a long-term animal study, which suggested that chromium-6 may be a human carcinogen if ingested. The US EPA is now reviewing data from that study; w hen the review is completed, the US EPA will consider this and other information to determine whether the drinking water standard for total chromium needs to be revised.

  • Perchlorate salts are man-made compounds used as combustion accelerants, primarily in solid-fueled rockets and missiles. It can also be found in some munitions, fireworks, road flares and is thought to exist naturally in some nitrate-based fertilizer products.

  • Manufacturing waste and improper disposal of perchlorate-containing compounds are increasingly being found in groundwater and local drinking water wells.

  • The presence of perchlorate salts in wells and drinking water sources has been linked to hormonal balances and impedes human reproduction and development.

  • The U.S. Environmental Protection Agency (EPA) determined that perchlorate meets the Safe Drinking Water Act criteria for regulation as a contaminant. The agency found that perchlorate may have an adverse effect on the health of persons and is known to occur in public water systems with a frequency and at levels that it presents a public health concern.

  • EPA is currently developing a proposed national primary drinking water regulation for perchlorate.

  • Infectious diseases caused by bacteria, viruses and parasites are the most common and widespread health risk associated with drinking water. Outbreaks of disease caused by these pathogens are found less often in the Unites States (US) and other developed countries than in the rest of the world. However they continue to occur in the US because of inadequate water treatment or contamination after treatment.

  • Water-related infectious disease agents can be divided into two groups:

  • Waterborne pathogens are excreted or shed by infected humans and/or animals. These are referred to as enteric pathogens since they initially infect the intestinal tract, although many are capable of infecting other organs in the body. Waterborne organisms may be transmitted by direct ingestion of water, or indirectly by contamination of food or skin during washing.

  • Water-based pathogens are those organisms naturally present in water such as Legionella bacteria, blue-green algae, and certain parasites. They usually cause health-related problems only when they are allowed to grow excessively in certain environments (e.g. hot water heaters).

Polychlorinated Biphenyls
  • PCBs are a group of organic chemicals which can be odorless or mildly aromatic solids or oily liquids. BCBs were formerly used in the United States as hydraulic fluids, plasticizers, adhesives, fire retardants, way extenders, de-dusting agents, pesticide extenders, inks, lubricants, cutting oils, in heat transfer systems, carbonless reproducing paper.

  • USEPA regulates PCBs in drinking water to protect public health.

  • Potential health problems include: damage to skin, problems with the thymus gland, immune deficiencies, or reproductive or nervous system difficulties, and an increased risk of getting cancer. (USEPA)