To better understand the water pollution problem and what we can do about it, we present an overview of what water pollution is and what causes it.
Water pollution means that harmful substances, such as chemicals and microorganisms, contaminate surface water and groundwater.
Sadly, water pollution is most often caused by human actions and it causes one of the most valuable resources we have becomes toxic to us and to the environment.
Water is able to dissolve more substances than any other liquid on earth - it's why it is so easily polluted.
There are many ways to classify water pollution: surface water, groundwater, marine, point source, non-point source, chemical, pathogen, physical, organic, inorganic...
Surface water is covering 70% of the earth - oceans, lakes, rivers. In only 100 years we have managed to pollute our surface waters to the extent that they are not even fit for swimming, let alone drinking. This source often gets polluted by directly discharging sewage and industrial waste to rivers and oceans.
Such pollution mostly occurs in developing nations, although also developed countries are not immune to it, they only do it more discreetly.
Groundwater contamination depends on soil characteristics and geology, it is caused by sewage, fertilizers, pesticide use, industrial leaks...40% of Americans and 75% of EU inhabitants rely on groundwater which becomes drinking water after being pumped to the earth's surface.
Cleaning groundwater from contaminants is very difficult or even impossible. Once polluted, this water source can be unusable for thousands of years.
Point sources have one identifiable cause of pollution, such as pipe or ditch. A good example would be a factory discharging contamination legally or illegally.
Non-point means that the source is more diffused, like agriculture for example. Often it is the cumulative effect of smaller amounts of contaminants gathered from larger areas. Nitrogen compounds from agricultural lands are the result of such pollution.
The agricultural sector is the biggest consumer of global freshwater resources and also a major water polluter. Along with nitrogen, phosphorus is the primary threat to water quality worldwide.
Wastewater and sewage are used water - 80% of it flows back into the environment without being treated. It can hold metal, solvents, oils, chemicals and also includes stormwater runoff (road salts, oils, grease, and debris).
Chemicals found in our water sources can also be naturally occurring (calcium, sodium, iron, magnesium). Some of these elements are welcome in our water as they have beneficial properties to the human body.
It all depends on their concentrations. High concentrations of naturally occurring substances can also have a negative effect on aquatic flora and fauna. But even more alarming is the fact that many chemical substances are highly toxic.
Pathogens are disease-causing microorganisms. They can lead to waterborne diseases. Most often pathogens that cause human health problems are salmonella, E. coli, viruses, and parasitic worms.
Aging infrastructure may cause leaky sewage systems which can cause such hazards to be found also in drinking water in developed countries.
Organic contaminants are detergents, water disinfection by-products, insecticides, herbicides and other chemical compounds, petroleum, industrial solvents, drugs...
Inorganic contaminants include acids from industrial discharges, ammonia, chemical waste, fertilizers (nitrates, phosphates), heavy metals, silt (sediments)...