Water Contamination

Any water source can become contaminated either with contaminants that are naturally present in the earth or contaminants that are introduced through human activity.  An example of the latter is microbial contamination.  Potable water, that will be used for drinking or cooking, must be free of contaminants that can damage our short- or long-term health.

Sources of contamination

Comprehensive Water Analysis

The best way to understand the quality of your water is through a comprehensive water analysis which will identify the levels of any contaminants present.  After which the appropriate water treatment technology can be applied.

This exercise is like a medical examination by your doctor, based on questions designed to detect the problem, often followed up with a laboratory test (e.g. blood work).

Water Contaminant Regulations

Each regional municipality typically has its own regulations that limit the permissible quantities of contaminants or elements present in potable water. It is advisable to be aware of the maximum mandatory or suggested contaminants level covered by local regulations. In the absence of local regulations, guidelines are published by international organizations such as the World Health Organization (WHO) Standards.

Most people take for granted their water supply and safety. Thankfully in large public systems, the standards are high for testing and treatment, and they are closely regulated by authorities like the EPA. Those who are on a private water source such as a well, lake, or other water source are on their own. They, themselves, are responsible for the quality of their water.

Water Contaminants

Water contaminants can generally be grouped into three groups: suspended solids, dissolved solids and microbiological concerns. These may not be the only classifications but cover many of the contaminants encountered in water supplies worldwide.

Suspended Solids

This describes material that exists in a suspended (insoluble) form in water, which will typically settle on the bottom of a glass or bottle as visible sediment. This type of contamination is very common in surface waters, such as rivers where water movement generates high turbidity. To remove this type of contamination, the physical method of filtration is employed. Different filter pore sizes allow for removal of particles to specific “micron” (millionth of a meter) ratings.

Dissolved Solids

This contaminant refers to material dissolved in the water. The solids are chemically dissolved as part of the water, and their concentrations are measured overall as total dissolved solids (TDS), and the maximum concentration allowed in drinking water is usually around 1000 ppm.

“Total dissolved solids” is a general measure of all solids dissolved while more detailed analysis will report the levels of individual dissolved substances (for example, calcium, magnesium, bicarbonates, and nitrates). Dissolved solids are generally in the form of “ions”, cations carrying a positive charge and anions carrying a negative charge.


This type of contamination is a major challenge in many parts of the world where water distribution systems are lacking or not in a good state of operation and where water is often stored at length. In any situation, the primary concern is to eliminate illness-causing pathogens that may be present in the water.

Illustration of giardia

There are three main groups of pathogens that are often found in water sources that can cause illness in humans. These are bacteria, protozoa and viruses.


The bacteria most often discussed is E.coli.  It is a type of coliform bacteria. Coliforms are bacteria that are naturally present in the environment and also live in the intestinal tracts of animals. The presence of coliforms indicates a general water quality issue. However, if E.coli is found in the water, it indicates the presence of fecal contamination and  signals an elevated risk of pathogens also being in the water. Some other waterborne bacteria of concern are Salmonella, Shigella and Campylobacter.


Giardia and Cryptosporidium are both organisms that live in the intestinal tracts of animals. As part of their lifecycle, both organisms are flushed out with feces and form an extremely difficult-to-penetrate cyst to protect them, even in harsh environments. These organisms can persist, even in cold water, for months in the environment until they are ingested and start the cycle over again.

They typically originate from surface water intrusion due to flooding events or poor well construction or the deterioration of well components. Both Giardia and Cryptosporidium can cause illness, and in children, the elderly, or immune-compromised people, they can be serious illnesses. Because of their protective cyst coatings these organisms are resistant to disinfection with chlorine.


Waterborne viruses like norovirus or Hepatitis A can be found in many different water sources.  They are highly prevalent in surface water but have been found in groundwater too.  Shallow wells or wells in fractured bedrock are more vulnerable to contamination by viruses.

UV Disinfection for Microbial Contaminants

At proper doses, ultraviolet disinfection can be effective against most microbes found in water.