Chemical Contaminants in Water

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Have you ever wondered what the major causes of the chemical contamination of our precious water supply are? Or, perhaps you've wondered what important chemical contaminants are? This lesson outlines both.

Chemicals in the Water

In most parts of the U.S., drinking water is quite safe. This, of course, can't be said for every part of the country. The recent water crisis in Flint, Michigan comes to mind, where lead was found to be in their poorly treated water. Plenty of nations around the world have a lack of clean drinking water.

So what is clean? Water can have many chemical contaminants. There are literally hundreds of them. While this lesson is not an exhaustive list of each chemical contaminant that may be found in water, it will give you a good idea of some examples and the variety of sources.

Natural Chemicals

When we think about chemical contamination of water, it's easy to fall into the trap of believing all of it is human-made. This is not true. Sometimes, a water system will have naturally occurring chemicals within it. A lot of these chemicals are derived from the soil and rocks found within a river, lake, or other body of water used as a source. Chemicals derived from these non-living entities are called inorganic. On the flipside organic chemicals, those with carbon from living entities like plants and algae, can be found in our water sources as well.

Natural inorganic chemical contaminants can cause discoloration of the water, this is especially true of iron and manganese. Chloride can contribute to a salty taste to the water while sulfate combined magnesium can actually cause the runs! Diarrhea is the least of our concerns when it comes to natural chemical contamination, however. Far worse are:


  • Arsenic, which can cause cancer and heart, respiratory, and neurological problems
  • Fluoride, too much of which can cause skeletal disorders
  • Selenium, high levels of which can lead to all sorts of skin, hair, and tooth issues
  • Nitrate, a substance that may lead to a serious blood disorder called methemoglobinemia

Natural organic (bio)chemicals, such as toxins produced by bacteria, can also cause people a lot of issues. One notable example of this is the production of toxins by an overgrowth (bloom) of cyanobacteria, sometimes called blue-green algae. Coming into contact, or drinking water contaminated with cyanobacterial toxins can cause everything from skin irritation to liver damage.

An overgrowth of cyanobacteria.

Human-Made Chemicals


Of course, we can't blame nature for all of our water troubles! We've done our fair share of contamination too. Nitrates and pesticides are the most common source of chemical contamination of drinking water as a result of agriculture. Add to that animal manure, fertilizers, and even human feces and sewage used in agriculture, and excess nutrients like phosphorus found therein contribute to the overgrowth of microorganisms in water. This can poison the water with various toxins as a result.

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