5 Common Water Contaminants

The quality of our drinking water is something that we have always taken for granted. However, the world is changing rapidly and so too are our concerns. Fracking, pollution, misuse of land, and an increasing population each threaten the quality of our drinking water.

Contaminants in our water can be both naturally occurring and formed as by-products during the water treatment process. In this article we’ll take a look at 5 common water contaminants and how they might affect you.


1) Arsenic

Arsenic is famed for its use as an ancient poison, but natural geology and the activity of us humans mean arsenic can be found in our drinking water supply. Arsenic is a carcinogen (it causes cancer) and just one teaspoon of arsenic oxide could kill 40 adults. It is also tasteless and odorless.

Arsenic is unfortunately for us a naturally occurring element in the earth’s crust. By dissolving from soil and rocks, it often seeps into underground aquifiers (A layer of rock that holds water). Drinking water that is taken from underground aquifiers may contain a wide range of arsenic concentrations. These values range from 1 microgram per liter (MG/L) to 1000 MG/L. The maximum amount allowed in US drinking water by law is 0.01 MG/L. If arsenic is not specifically removed during the water treatment process then when ingested it will accumulate in your body. Concentrations of arsenic as low as 2 MG/L can have dangerous consequences on human health over time.

Arsenic Cancer Risk

Lifetime Arsenic Cancer Risk (Source: simplewater.us)

Health Fact: The US Environmental Protection Agency (EPA) campaigned to reduce the maximum arsenic level allowed in American drinking water. In 2001, the Public Health Standard was reduced from 0.05 MG/L to 0.01 MG/L. Health experts actually advocated a much lower level of 0.003 MG/L but were put off by the huge costs of improving water treatment facilities.

Health effects of overexposure: Cancer, lung damage, lowered IQ, cardiovascular disease, renal failure.

Arsenic levels in U.S. groundwater

Arsenic levels in U.S. groundwater (Source: publicintegrity.org)




2) Fluoride

Fluoride has been added to American water supplies since the 1940’s. Its purpose is to reduce dental cavities. By binding to tooth enamel, fluoride makes teeth more resistant to acid and bacteria, and helps prevent tooth decay. It is thought that around 75% of U.S. public water has added fluorine.

But this sounds great right?

Well the addition of fluoride to our water divides opinion. It is endorsed by the American Dental Association, American Medical Association, and Centers for Disease Control and Prevention (CDC). The CDC actually regards the fluoridation of drinking water as one of the 10 biggest achievements in public health in the 20th century.

However, there are opponents and reasons to wary. Opposition to fluoridation arises from studies which indicate that large levels of fluoride can impair brain function and development. A 2012 study published in the Environmental Health Perspectives journal linked naturally occurring high fluoride levels in public drinking water and children with lower IQs. They actually investigated the results of various studies and concluded that 26 out of 27 studies found links between drinking water containing high fluoride levels and lower IQ.

Perhaps dental fluorosis is the more common concern though. Caused by excessive exposure to fluoride, dental fluorosis can cause white streaks, pits, brown stains, and broken enamel. The CDC reports that 41% of 12-15 year olds suffer from some form of dental fluorosis.

So is the fluoride in our water good or bad?

There is no definitive answer, and it depends very much on who you ask and where you get your information. What is certain though is that fluoride is undeniably toxic at high concentrations.

Health effects of overexposure: Bone disease, dental fluorosis.


3) Lead

Lead is a naturally occurring metal which exposure to can cause many adverse health effects. It is particularly dangerous for children and babies as it may stunt their mental and physical development. Long term exposure for adults can cause kidney problems and increased blood pressure.

Lead is commonly used as a plumbing material and can enter our drinking water supply through the corrosion of pipes or fixtures. Lead used in plumbing systems is more likely to be a problem for homes built pre-1986. Chrome or brass plated fixtures and faucets may be particularly problematic as they can contain up to 8% lead. The Massachusetts Water Resources Authority states that most faucets purchases before 1997 were constructed of brass or chrome plated brass.

How do I minimize my exposure to lead?

  • Run the kitchen faucet for one minute in the morning (Lead is more likely to leach in to water if it sits in the pipes for a long time)
  • Only use cold water for drinking (Hot water may sit in a tank for a long time).

Health effects of overexposure: Development problems in children, concentration and attentions span issues in children, high blood pressure, kidney problems.


4) Chromium

Chromium is a naturally occurring metallic element found in plants, soil, rocks, and even animals. It is odorless and tasteless. There are two forms of chromium which are found in water. They are trivalent chromium (chromium-3) and hexavalent chromium (chromium-6). Chromium-3 is actually essential to our diet and can be found in meat, vegetables, grains, and fruit. Chromium-6 is more toxic and besides occurring naturally can also be produced through industrial processes. Chromium-6 has been known to be released into the environment because of poor storage, and insufficient waste disposal methods. Chromium-6 is thought to be a carcinogenic when ingested. The research of the Environmental Protection Agency (EPA), World Health Organization (WHO), and National Toxicology Program (NTP) support this thought. The EPA are actually working towards completing a new health assessment and review of the drinking water standard of chromium-6.


5) Chlorine, Chloramine, and Chlorine Dioxide

Chlorine, Chloramine, and Chlorine Dioxide are chemical disinfectants which are commonly added to our water supply to protect us from disease-causing pathogens. While chlorine can be an effective weapon, the disinfection process is not without problems. Certain bacteria are very resistant to the process, and minerals in water can even react with the chemical disinfectants to form harmful by-products (Such as haloacetic acid and trihalomethanes). A delicate balance must be struck at the water treatment facilities between the potential danger of the by-products and the benefits of the disinfectant chemicals.

Health effects of overexposure: Irritation of eyes and nose, stomach discomfort, anemia, nervous system effects on the pregnant and young.


References and Sources

Simple Water

United States Environmental Protection Agency

Oxford Journal

Centers for Disease Control and Prevention

Live Science

Massachusetts Water Resources Authority

Scientific American


See how we rate the best reverse osmosis systems on the market at protecting you from harmful pollutants, in our RO system comparison article.


Hi I'm Jamie, teacher and owner/chief contributor at waterfilteranswers.com. We strive to bring you the most informative water filter reviews in the most intuitive and user friendly way. Besides offering advice on the water filter to suit your needs, we also post topical articles on water pollution and the environment. Stay connected and follow us on, Facebook, Twitter, Google+ and more!

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