21 Most Common Contaminants Found in Drinking Water


21 Most Common Contaminants Found in Drinking Water

Do you drink tap water?

You might be surprised to learn that the drinking water in your home could contain harmful contaminants. In fact, there are more than 350 known contaminants in our nation’s drinking water.

Fortunately, there are many ways to protect yourself and your family from these dangerous chemicals. Most can be effectively removed from your drinking by using a simple filter or other treatment system.

These filtration systems can either be used treat all of the water where it enters your home, or you can install a point-of-use device to treat it at your faucet.

In this article, we review the 21 most common contaminants found in our drinking water and what you can do to protect yourself and your family.

What is a Drinking Water Contaminant?

General considerations about pure waterTap water contamination - color

Before we discuss contaminants in drinking water, we need to know what the definition of a contaminant is.

  1. Health concerns. Is a contaminant something that harms our health? The obvious answer is – Yes! Our health is the most important concern we have when it comes to drinking water. We all want our drinking water to be pure and free of anything that might make us sick.
  2. Taste. What about taste? No one wants to drink water that tastes bad. So, anything that doesn’t taste good is considered a contaminant.
  3. Odor. Is something that smells bad a contaminant? I think most people would say “yes”. We should, therefore, include compounds that have a foul odor in the contaminant category.
  4. Color and clarity. Do you care about the appearance of your drinking water? Is cloudy or discolored water a concern for you? If you’re like most people, you want your water to be clear and pure. Anything that degrades the visual aesthetics of water is a contaminant.
  5. Staining and scaling. Some water has minerals and other compounds that stain our clothes or create scale in our sinks and showers. Are these substances contaminants? Generally speaking, yes. We consider chemicals that cause staining and scaling a problem and consider them contaminants, too.

The 4 Categories of Drinking Water Contaminants

Drinking water is regulated in the United States by the Safe Drinking Water Act. This legislation defines a “contaminant” as any physical, chemical, biological, or radiological substance that is present in water. Some water contaminants may be harmful if they are present above a particular level, while others are harmless. It is important to note that the mere presence of contaminants in drinking water does not necessarily mean that it presents a health risk.

1. Physical contaminants

Physical contaminants impact the physical appearance or other properties of water. Examples include sediment, organic material suspended in lakes from soil erosion and pest control measures like bacteria that are used to rid these bodies of unwanted substances such as algae blooms when it becomes unsafe for swimming due to poor quality conditions.

2. Chemical contaminants

Chemical contaminants are substances which can be either naturally occurring or man-made. They may include things like nitrogen, bleach and salts as well pesticides or metals. They may be found in a variety of places around the world including water sources. Other examples include pharmaceuticals that are improperly disposed of our excreted through our bodies.

3. Biological contaminants

Microbial contamination is any organism that lives in water and can cause a wide array of health problems. Bacteria, viruses, protozoa or parasites are all examples of what we call “biological contaminants.” They’re not only dangerous to humans but also animals like fish who may become infected with these microscopic bugs through consumption!

4. Radiological contaminants

Radiological contaminants are materials that can release ionizing radiation. Cesium and plutonium, for example, have an unbalanced number of protons and neutrons resulting in unstable atoms which emit these dangerous particles when they decay over time. Some radiological elements include cesium, plutonium or uranium.

Secondary Maximum Contaminant Levels

In addition to potential health effects from contaminants in drinking water, people are also concerned about qualities like taste and odor. These properties are very noticeable, and they often determine whether we find the drinking water acceptable or not.

These qualitative properties are referred to as “secondary” because they do not affect the safety of the water. However, just because taste and odor don’t make us sick, they are important because no one wants to drink water that smells or tastes bad.

The US EPA established guidelines for public water supplies to deal with these qualitative issues.

The following table presents the secondary maximum contaminant levels in drinking water

Contaminant SMCL Noticeable Effects above the SMCL
Chloride 250 mg/L Salty taste
Copper 1 mg/L Metallic taste
Corrosivity Non-corrosive Metallic taste
Foaming agents 0.5 mg/L Bitter taste, odor
Iron 0.3 mg/L Metallic taste
Manganese 0.05 mg/L Bitter metallic taste
Odor 3 TON* Rotten-egg, musty or chemical smell
pH 6.5 – 8.5 SU Low pH: bitter metallic taste
High pH: soda taste
Sulfate 250 mg/L Salty taste
Total Dissolved Solids 500 mg/L Salty taste
Zinc 5 mg/L Metallic taste

Learn more about iron in drinking water:
Iron Filter for Well Water: How to Remove Iron from Your Water
Does Reverse Osmosis Remove Iron from Drinking Water

Read my articles about odors in drinking water and how to remove them.
Do Brita Filters Remove Odors? A Look at the Science
Why Does My Tap Water Taste and Smell Bad (and How to Treat It)
Do Carbon Filters Remove Sulfur Smell from Water?
Get Rid of Rotten Egg Smell in Your Drinking Water
8 Reasons Why Your Water Tastes or Smells Like Metal

21 Common Contaminants Found in Drinking Water

Now that we have a good understanding of water quality and what makes something a contaminant, we can evaluate the various chemicals and elements that degrade our drinking water.

Here are the most common contaminants found in drinking water in the United States.

  1. Aluminum
  2. Ammonia
  3. Arsenic
  4. Atrazine
  5. Barium
  6. Cadmium
  7. Chlorine treatment by-products
  8. Chromium
  9. Copper
  10. Fluoride
  11. Lead
  12. Mercury
  13. Nitrates/Nitrites
  14. Pathogens (Bacteria & Viruses)
  15. Perchlorate
  16. Pharmaceuticals
  17. Radioactive compounds (radium, uranium)
  18. Selenium
  19. Silver
  20. Vinyl chloride
  21. Emerging contaminants

The following section presents a detailed discussion of the most common drinking water impurities. It includes a description of what they are, where they come from, their health impacts, and what you can do to remove them from your water.

1. Aluminum contamination in drinking water

Water Distiller
Distillation can remove aluminum from drinking water

Aluminum is an abundantly available metal found in the earth’s crust, and it can be present in drinking water as either aluminum hydroxide or sodium aluminate. These compounds are created during clarification and precipitation softening processes.

Sources of aluminum contamination: Aluminum leaches into groundwater from rocks and soil. It is often detected in groundwater at concentrations ranging from 0.1 ppm to 8.0 ppm.

Health effects of aluminum: The USEPA has not established a drinking water limit for Aluminum because it is not harmful to human health – one exception, aluminum poses a significant risk for dialysis patients.

The USEPA established a Secondary Maximum Contaminant Level (SMCL) between 0.05 to 0.2 mg/L or ppm. A SMCL limit is based on nuisances such as taste or odor and not health concerns. For aluminum, the standard is based on color changes that may occur.

Treatment methods for aluminum in drinking water: Aluminum can be removed from drinking water with cation exchange, distillation, or reverse osmosis.

2. Ammonia contamination in drinking water

Ammonia is a colorless, pungent gaseous compound of hydrogen and nitrogen that is highly soluble in water.

Sources of ammonia contamination: Ammonia is a byproduct of natural processes, but it can also enter the water supply through industrial wastes and fertilizers.

It has been used for decades in municipal treatment systems with chlorine to make sure that drinking water is adequately disinfected.

Health effects of ammonia: The USEPA has not established a MCL for ammonia. Since early in this century, it has been known that ammonia is toxic to fish and the toxicity increases with increasing pH or temperature of water.

Treatment methods for ammonia in drinking water: Ammonia can be removed from drinking water by ion exchange with zeolite, sodium alumino silicate zeolites, or distillation.

3. Arsenic contamination in drinking water

Arsenic is a naturally occurring element that can be found in many places around the world, but it’s most frequently associated with ancient rock formations. The EPA estimates that 36 million Americans drink arsenic-contaminated water, with more than three parts per billion.

Sources of arsenic contamination: Arsenics enters ground water through erosion or from manmade sources such as wood preservative and petroleum production – especially when they’re not handled properly during manufacturing processes. Other sources include improper handling of toxic chemical waste products like pesticides.

Health effects of arsenic: Arsenic causes several health effects including serious skin problems, endocrine disruptor, certain types of cancer (skin, bladder, lung, kidney, liver, prostate), and cardiovascular & nervous system harm.

Treatment methods for arsenic in drinking water: There are several effective treatment technologies that can be used to remove arsenic from drinking water. Commonly used treatments for arsenic include adsorption with iron oxide/ hydroxides, activated alumina, iron-based specialty media impregnated or coated with iron oxide/hydroxides, distillation, titanium oxy/hydroxide, anion exchange (strong base anion exchange resins), manganese greensand, and reverse osmosis (RO).

Read my articles on arsenic treatment:
7 Methods to Remove Arsenic from Drinking Water
Do Brita Filters Remove Arsenic? The Answer May Surprise You

4. Atrazine contamination in drinking water

The most commonly detected pesticides in U.S waters are often endocrine-disrupting chemicals that have serious health impacts. One such chemical is atrazine. This pesticide it’s primarily found throughout parts of Midwest or southern United States.

Sources of atrazine contamination: Atrazine is a pesticide that is widely used throughout the country. In areas where it is applied, it is detected in drinking water.

Health effects of atrazine: Atrazine is an endocrine disruptor. Endocrine disruptors are chemicals that can interfere with our endocrinology (or hormonal) systems. These disruptions cause cancerous tumors and other developmental disorders, including birth defects in fetuses of pregnant women exposed to them during pregnancy

Treatment methods for atrazine in drinking water:

Atrazine can be reduced below 3 parts per billion (ppb), the drinking water standard, using granular activated carbon filtration.

5. Barium contamination in drinking water

Barium is a divalent cation and an alkaline earth metal that occurs in natural mineral deposits.

Sources of barium contamination: Barium in drinking water comes from improper disposal of drilling wastes, mineral deposits, smelting of copper, and motor vehicle parts manufacturing.

Health effects of barium: Ingesting high levels of soluble barium over the short term has resulted in difficulties breathing, increased blood pressure and changes to heart rhythm among other things. The USEPA set their Maximum Contaminant Level Goal at 2 mg / L (or ppm). Barium compounds that do not dissolve well in water are often used by doctors to treat certain medical problems.

Treatment methods for barium in drinking water: Barium can be removed from drinking water using ion exchange (cation), reverse osmosis filtration, and distillation.

6. Cadmium contamination in drinking water

Cadmium is found in zinc ores, lead and copper deposits, coal and other fossil fuels, shales, and is released during volcanic action. Groundwater and surface water can both be influenced by these deposits, particularly when they come into touch with low total dissolved solids (TDS) or acid waters.

Cadmium is also found in many vegetables that we consume. Generally, this metal is present in dissolved form as an ion in water.

Sources of cadmium contamination: Cadmium contamination can be the result of deterioration in galvanized plumbing, along with industrial waste contamination or surface water contamination by certain fertilizers.

Health effects of cadmium: Cadmium causes both short-term and long-term health affects in people. Short term exposure to cadmium can cause nausea and vomiting along with diarrhea. Other short-term problems include muscle cramps, convulsions, and shock. More serious health harms include sensory disturbances, liver damage, and renal failure. Long-term exposure to cadmium is known to cause kidney, liver, bone and blood damage.

Treatment methods for cadmium in drinking water:

Cadmium can be removed from drinking water using coagulation followed by filtration, ion exchange, lime softening, reverse osmosis, or distillation. RO is the most commonly used treatment method in residential settings.

7. Chlorine treatment by-product (THM) contamination in drinking water

Municipalities add chlorine to drinking water to disinfect it. This chlorine reacts with organic material to form by-products know as trihalomethanes (THMs). Chemicals that are formed during chlorination include monochloramine, dichloramine, and nitrogen trichloride.

Sources of THM contamination: The most common source of THM in drinking water is the addition of chlorine. This is a necessary step to neutralize pathogens like bacteria, viruses, and parasites.

Health effects of THM: The harmful byproducts of disinfection have been linked to an increased risk for cancer and infant birth delivery problems. It is estimated that THMs in drinking water are responsible up 2-17% among bladder cancers diagnosed each year. To protect public health, the USEPA has established a maximum contaminant level at 0.08 mg/L or 0.08 parts per million.

Treatment methods for THM in drinking water: THM can be effectively removed from drinking water with activated carbon filters and catalytic activated carbon. The catalytic carbon is usually not used in residential treatment systems because of its cost – and regular activated carbon works extremely well.

Read my articles on removing chlorine from drinking water:
7 Top Methods to Remove Chlorine from Drinking Water
Do Carbon Filters Remove Chlorine and Chloramine from Water?
Do Refrigerator Water Filters Remove Chlorine? Everything You Need to Know
Do Brita Filters Remove Chlorine? A Comprehensive Look
Does Reverse Osmosis Remove Chlorine from Drinking Water?
Does Boiling Water Remove Chlorine from Drinking Water?

8. Chromium contamination in drinking water

Chromium is a tasteless, odorless metallic element. It is found in many natural sources such as rocks, plants, soil and volcanic dust.

Sources of chromium contamination: The release of hexavalent chromium into our water sources is an issue that needs to be addressed. The chemical has been found in many vegetables, fruits meats grains and yeast but can also come from industrial processes through poor housekeeping or leaks at waste disposal sites. Other sources include hazardous materials like paints, wood preservatives, chrome plating, and natural sources.

Health effects of chromium: Long-term consumption of water containing chromium in excess of the maximum contaminant level (MCL) can be unhealthy. The USEPA established the MCL for total chromium at 0.1 mg/L.

Some of the adverse health effects associated with chromium exposure include occupational asthma, eye irritation and damage to skin as well. It can also lead to a number of other diseases including respiratory irritancy or congestion, pulmonary disease, kidney problems, and liver issues.

Treatment methods for chromium in drinking water:

The most effective way to remove chromium-6 from drinking water is either reverse osmosis filtration, carbon adsorption, or micron filtration.

9. Copper contamination in drinking water

Copper is an essential mineral for human health and too little can be unhealthy, but levels over 0.05 mg/L are not naturally encountered in drinking-water.

Sources of copper contamination: The presence of copper could come from industrial discharges or salt used to control algae blooms on reservoirs; another source at points where plumbing materials have been applied such as Corrosion Protection Chemicals (CPCs).

Health effects of copper: Exposure to high levels of copper (acute exposure) can result in copper poisoning. Symptoms of this illness include nausea, vomiting, diarrhea, gastrointestinal illness, abdominal and muscle pain. Severe cases of copper poisoning have led to anemia, liver poisoning, and kidney failure.

Treatment methods for copper in drinking water:

Copper can be removed from drinking water using reverse osmosis filtration, distillation, or ion (cation) exchange resins. RO is the most commonly used treatment method for copper in residential drinking water applications.

Read my article on copper treatment methods.
Does Reverse Osmosis Remove Copper

10. Fluoride contamination in drinking water

Fluorine is a natural mineral that may be found in almost all soils. It makes up approximately 0.08 percent of the earth’s crust.

Sources of fluoride contamination: Fluoride is added to public drinking water – at about one milligram per liter (mg/L) – to prevent tooth decay. It is also abundant in soils and rocks, which is why it’s present in many groundwater supplies.

Health effects of fluoride: Skeletal fluorosis can develop in individuals who have been exposed to drinking water containing more than 4 mg/L for many years. It’s a serious bone disease that resembles osteopetrosis and is characterized by extreme density and hardness and damaged fragility of the bones.

Children under the age of nine who are exposed to fluoridated water in doses greater than about 2 mg/L may develop mottling or discoloration of their permanent teeth.

The USEPA established a secondary maximum contaminant level (SMCL) requirement of 2 mg/L in drinking water to prevent fluorides from creating aesthetic or cosmetic damage.

Treatment methods for fluoride in drinking water:

Drinking water with fluoride can be treated using reverse osmosis filtration, strong base anion exchange, activated alumina adsorption media, or distillation. RO is very effective and is the most commonly used treatment method for residential drinking water contaminated with fluoride.

Read my comprehensive articles on fluoride treatment for drinking water.
Does Reverse Osmosis Remove Fluoride from Drinking Water? My Data
Do Brita Filters Remove Fluoride? The Answer Might Surprise You
The Complete Guide to Fluoride Water Filters
Do Refrigerator Filters Remove Fluoride? Surprising Answer

11. Lead contamination in drinking water

Lead is a metallic element with a sweet taste. When released to land, lead binds very tightly to soils and does not migrate far. Due to this property, lead is very rarely detected in groundwater above trace levels (10 ppb or less).

Sources of lead contamination: Lead contamination in drinking water comes primarily from the water pipes used to convey it to our homes. This includes components such as lead service lines, lead containing solder, and brass fittings. A secondary source of lead contamination in drinking water comes from industrial processes, mines, and smelting operations that contaminate the sources of drinking water.

Health effects of lead: Lead is a ubiquitous metal that can damage the human body. Varying levels of exposure have been shown to cause notable health effects, including death in extreme circumstances following ingestion of high concentrations.

Lead causes harm to the brain, kidneys, and bone marrow, even at very low exposure levels. Coma and convulsions also occur with low exposures to lead. Lead can also damage a person’s nervous system and red blood cells.

When it comes to the risks of ingesting lead, children are more likely than adults to suffer harm. Reduced intelligence, impaired hearing and decreased growth, are associated with lead exposure in children.

Treatment methods for lead in drinking water:

Lead contaminated drinking water can be treated using reverse osmosis filtration, carbon adsorption filters (not all types of carbon remove lead), ion exchange resin (strong acid cation exchange), and distillation. RO is the most effective treatment method for lead in drinking water.

Learn about treating lead contaminated drinking water.
How to Remove Lead from Drinking Water in Your Home: 4 Quick and Effective Tips
Reverse Osmosis Filtration: Removing Lead from Drinking Water
Brita Filters: Which models remove lead from drinking water?
Do Refrigerator Filters Remove Lead? Comprehensive Evaluation
Lead in Drinking Water – Top 50 Trusted Online References

12. Mercury contamination in drinking water

Mercury is a naturally occurring metal that has several forms. Mercuric salts are naturally occurring inorganic chemical compounds. Metallic mercury is a shiny, silver white liquid with no odor. It is a liquid at room temperature and pressure.

Sources of mercury contamination: Mercury is a highly toxic element that can accumulate in fish tissue over time. Methyl mercury is primarily produced by microscopic organisms present in both water and soil. Burning coal also emits a significant amount of mercury to the atmosphere. All of these sources can cause contamination of surface water and groundwater that are used for drinking.

Health effects of mercury: People are often exposed to high levels of mercury through the environment, food sources and dental work.

High levels of metallic, inorganic, or organic mercury can severely harm the brain, kidneys, and fetus during pregnancy. Changes in the brain’s functioning can result in irritability, shyness, tremors, vision or hearing problems, and memory difficulties.

Treatment methods for mercury in drinking water: Treatment methods for drinking water contaminated with mercury include distillation, reverse osmosis filtration, activated carbon filters, and properly designed submicron filters.

13. Nitrates/Nitrites contamination in drinking water

Most nitrogenous materials in natural waters are turned into nitrates. So, even if they are organic or ammonia, they will usually be turned into nitrates.

Sources of nitrate and nitrite contamination: Nitrate contamination comes from sources such as human sewage and livestock manure, fertilizer run-off from agricultural lands, and erosion of natural deposits.

Health effects of nitrate and nitrite:

Nitrate and nitrate exposure can cause negative health affects in humans. Infants who drink nitrates can develop methemoglobinemia, known as blue baby syndrome. Most potential health effects are seen in infants under the age of 6 months. Very high levels of nitrate can cause central nervous disorders in adults

The USEPA set the Maximum Contaminant Level Goal (MCLG) in drinking water at 10 mg/L total nitrate. They also established an MCLG and an MCL of 1 mg/L for nitrite, and an MCL of 10 mg/L for total nitrate plus nitrite.

Treatment methods for nitrate and nitrite in drinking water: Drinking water contaminated with nitrates and nitrites can be treated using reverse osmosis with thin film composite membrane, ion exchange resin (anion Type I and II), nitrate “selective” anion exchange resins, distillation, and electrodialysis.

Read my article on nitrate treatment.
Does Reverse Osmosis Remove Nitrates? – Find Out Here!

14. Pathogens (bacteria & viruses) contamination in drinking water

Not all microbial contaminants can be recognized by sight, odor, or taste. Although some waterborne microorganisms might cause disease, many species are non-threatening or even beneficial. Many water supplies naturally host a variety of microorganisms, although some are more harmful than others.

The most common pathogens encountered in drinking water are bacteria, viruses, and cysts.

Sources of pathogen contamination: Sources of biological pathogens in drinking water include agriculture runoff (e.g., dairy farms and livestock operations), cross-contamination from sewer systems, and inadequate chlorination at municipal drinking water plants.

Health effects of pathogens: The most dangerous microbial contaminants are E coli and giardia. They can cause gastrointestinal problems, flu-like symptoms or other diseases that mimic those caused by food poisoning.

Treatment methods for pathogen in drinking water: Treatment methods used to inactivate biological pathogens in drinking water include chlorination, UV light, reverse osmosis, and ozone oxidation. Boiling can also be used to treat drinking water. Read my detailed article on using reverse osmosis to remove bacteria and viruses from drinking water.

Read my articles on removing bacteria and other pathogens from drinking water.
Does Reverse Osmosis Remove Bacteria from Drinking Water?
How to Remove Bacteria from Drinking Water
6 Ways to Remove Viruses from Drinking Water

15. Perchlorate contamination in drinking water

Perchlorate is both a naturally occurring as well as man-made inorganic chemical. Perchlorates are used to manufacture fireworks, explosives and other pyrotechnics throughout the world, but they can also be found contaminating soils from areas where munitions were manufactured over 50 years ago.

Sources of perchlorate contamination: Inorganic in nature, perchlorate is a component of fireworks, explosives, and rocket propellants. Low levels of perchlorate are known to occur naturally as well.

Health effects of perchlorate: The use of perchlorate, a chemical used in rocket fuel and fireworks, has been linked to developmental and learning issues in children. If ingested, it inhibits the absorption of iodine, an important element for the proper functioning of the thyroid glands.

Treatment methods for perchlorate in drinking water: Perchlorate contamination can be removed from drinking water by reverse osmosis filtration, ion exchange resins (anion exchange) and distillation.

16. Pharmaceutical contamination in drinking water

Pharmaceuticals are synthetic chemicals that can be found in prescription, therapeutic and veterinary medication. These drugs often end up going down the drain from poorly controlled manufacturing facilities or through improper disposal methods.

Sources of pharmaceutical contamination: Pharmaceuticals are a common source of water pollution. They enter the environment through human excretions, improper disposal, and poorly controlled manufacturing facilities.

These discharges lead to contamination of surface water and groundwater. You may believe wastewater treatment facilities would handle it, but pharmaceuticals go through water treatment.

Health effects of pharmaceuticals: The potential for hormones and pharmaceuticals to be present in drinking water is a concern because they could affect human health at low doses. These compounds disrupt internal biological processes like development, growth or reproduction that are regulated by hormones. All of this can lead to adverse effects on our health if inadvertently consumed.

Treatment methods for pharmaceuticals in drinking water: Pharmaceuticals in drinking water are problematic. Treatment methods for removing pharmaceuticals from drinking water include activated carbon and reverse osmosis filtration. It is important to note that pharmaceuticals are a broad class of chemicals, and it is necessary to evaluate each specific drug to determine the best method of treatment. There is no “one size fits all” treatment method for pharmaceuticals.

17. Radioactive compounds (radium, uranium) contamination in drinking water

There are many sources of naturally occurring radioactive compounds in the environment. Radium is a rare, trace element that occurs commonly in all rocks and soil. It’s constantly being produced by the radioactive decay of uranium or thorium.

Sources of radioactive compound contamination: Surface water sources and shallow groundwater will typically have low to moderate levels of radioactive compounds (e.g., radium) while deeper groundwater may have higher concentrations, depending on several natural factors.

Health effects of radioactive compound: Exposure to radioactive compounds is known to cause certain types of cancer.

Treatment methods for radioactive compound in drinking water: Radioactive compounds can be removed from drinking water using ion exchange resins (cation exchange softening), reverse osmosis filtration, distillation, and lime softening. RO is the most commonly used method to remove radioactive compounds from drinking water in residential applications.

Read my articles on removing radioactive compounds from drinking water.
Do Brita Filters Remove Radium from Drinking Water: A Homeowner’s Guide
Does Reverse Osmosis Remove Radium from Drinking Water?
Do Carbon Filters Remove Radon from Drinking Water?
Does Reverse Osmosis Remove Radon from Drinking Water?
How Reverse Osmosis Removes Uranium from Drinking Water

18. Selenium contamination in drinking water

Selenium is a metal found in natural deposits as ores containing other elements. The greatest use of selenium compounds is seen with its use in electronic and photocopier components, but they’re also widely used for many other products too. Another source is from copper smelting industries which release this environmental toxin through poor waste management practices.

Sources of selenium contamination: Selenium is rarely encountered in groundwater. Most sources of drinking water contamination are from poorly managed hazardous wastes.

Health effects of selenium: Selenium is required in trace amounts by humans and higher doses produce clear toxic symptoms, according to studies. When people are exposed to high levels of selenium over a short period of time, it has been linked to the following health problems: damage to the peripheral nervous system, hair and fingernail loss, fatigue and irritability, kidney and liver damage, and nervous and circulatory system harm.

The USEPA established the Maximum Contaminant Level (MCL) in drinking water for selenium at 0.05 mg/L.

Treatment methods for selenium in drinking water: Selenium contamination in drinking water can be achieve using activated alumina adsorption, ion exchange media (strong base anion type I), distillation, and reverse osmosis filtration.

19. Silver contamination in drinking water

Silver is a precious metal that has been used for centuries as an antibacterial agent. There are no scientific studies to show it causes health problems in humans.

Sources of silver contamination: Silver is present in soil as insoluble silver chloride and silver sulfide. The primary source of contamination is from its use as a bacteriostat in water treatment systems.

Health effects of silver: Silver is retained indefinitely within tissue, especially skin, eyes, and mucous membranes, when ingested and absorbed. Silver toxicity can induce a variety of skin discolorations, such as blue-black or silver white. This effect, called argyria, does not have any negative effects on body functions.

The USEPA established a Secondary Maximum Contaminant Level (SMCL) for silver of 0.10 mg/L.

Treatment methods for silver in drinking water: Silver can be removed from drinking water using reverse osmosis filtration, distillation, and ion exchange resins (strong acid cation exchange).

20. Vinyl chloride contamination in drinking water

Vinyl chloride is a solvent that is used to make PVC plastic products and is an ingredient in many industrial processes.

Sources of vinyl chloride contamination: Vinyl chloride is usually found in groundwater at hazardous waste sites. It is also an industrial agent that is used to make other products – spills and poor waste management practices can release this compound to the environment.

Health effects of vinyl chloride: Vinyl chloride is a human carcinogen.

Vinyl chloride can irritate your eyes, skin, and mucous membranes. Long term exposure can cause permanent liver injury or even lead to cancer. It is known to cause neurologic and behavioral symptoms as well as changes to the bones of the hand.

Treatment methods for vinyl chloride in drinking water: Vinyl chloride can be removed from drinking water using air stripping – a process in which air is bubbled through contaminated water to strip (i.e., volatize) the dissolved gas. Reverse osmosis filtration is used to treat drinking water contaminated with vinyl chloride.

21. Emerging contaminant contamination in drinking water

Emerging contaminants are a synthetic or naturally occurring chemicals that have the potential to enter our environment and cause known adverse ecological effects as well human health problems.

Three emerging contaminants that are generating a lot of interest are PFAS, 1,4-dioxane, and microplastics.

PFAS, per-and polyfluoroalkyl substances, are a group of chemicals used to make special coatings and products that resist water, heat, oil, and stains.

1,4-dioxane is a synthetic chemical that is used as a solvent stabilizer and an ingredient in many industrial processes.

Microplastics are small particles of plastic that have been detected in more than 90% of all drinking water.

Sources of emerging contaminant contamination: Emerging contaminants are released into the environment through poor housekeeping, spills, and improper disposal of industrial wastes. They contaminate drinking water through discharges to surface water bodies and releases to groundwater.

Health effects of emerging contaminants: The health effects of emerging contaminants depend on the specific chemical involved.

PFAS compounds cause a variety of negative health effects including liver damage, thyroid disease, decreased fertility, high cholesterol, obesity, hormone suppression and cancer.

1,4-dioxane is a suspected human carcinogen. Short-term exposure can cause vertigo, drowsiness, headache, and irritation of the eyes, nose, throat, and lungs.

Treatment methods for emerging contaminants in drinking water:

Emerging contaminants are often difficult to treat. Each compound has specific treatment methods that are used.

Treatment methods for PFAS contamination in drinking water include activated carbon adsorption, ion exchange resin (specific to PFAS), advanced oxidation processes, and reverse osmosis filtration.

Treatment of 1,4-dioxane in drinking water is achieved by advanced oxidation processes and ion exchange resins (specific to 1,4-dioxane).

Microplastics can be removed from drinking water using reverse osmosis, activated carbon filtration, and sediment filters. Only RO is able to achieve 99+% removal of microplastics.

Read my articles about removing PFAS from drinking water.
Eliminating PFAS from Drinking Water: Top Treatment Technologies
PFAS Contamination – Does Boiling Drinking Water Remove PFAS
Do Brita Filters Remove PFAS – Real World Testing Data
Does Your Refrigerator Water Filter Treat PFAS
Reverse Osmosis: How Well Does It Treat PFAS
Do Carbon Filters Remove PFAS and GenX Chemicals?
Do ZeroWater Filters Remove PFAS? The Definitive Answer
New Brita Filter Removes 11 PFAS Compounds – Purefast

Chief Guru

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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