What is Groundwater Contamination?

Mary McMahon
Mary McMahon

Groundwater contamination is a situation which arises when groundwater becomes polluted by substances of human origin. Since groundwater is generally regarded as safe to drink, groundwater contamination can become a serious issue, as people may drink the water, not realizing that it has become dangerous to consume. There are a number of potential sources of groundwater contamination, making regular testing of groundwater supplies critical to ensure that the water is still clean.

Oil spills can contaminate the ground, making remediation necessary.
Oil spills can contaminate the ground, making remediation necessary.

Groundwater is water which is stored underground. It forms when water from lakes, rivers, streams, snow melt, and rain trickles underground, becoming trapped there. When a deposit of groundwater is large enough to sustain human consumption, it becomes known as an aquifer. There are two primary types of aquifers: confined and unconfined. In a confined aquifer, the groundwater is surrounded by an envelope of impermeable rock, while an unconfined aquifer is surrounded by permeable materials, putting it at risk of contamination.

Regular tests ensure that groundwater remains safe for drinking.
Regular tests ensure that groundwater remains safe for drinking.

Chemicals, road salt, bacteria, viruses, medications, fertilizer, and fuel can all cause groundwater contamination. Some common sources of contamination include: leaking storage tanks, the use of chemicals in farms, landfills, poorly controlled hazardous waste sites, and septic systems. Groundwater contamination can also occur when factories dump materials into surrounding waterways, and when polluted runoff from storm drains reaches the aquifer.

Chemicals can pollute groundwater.
Chemicals can pollute groundwater.

Many nations have strict laws concerning the release of pollutants, to prevent groundwater contamination and other environmental problems associated with pollution. However, regular inspection of the thousands of potential sources of pollution is simply not possible, and nations rely on individual citizens and companies to exercise caution when it comes to handling and disposing of materials which could cause groundwater contamination.

Once the aquifer is contaminated, it is very difficult to clean up. Sometimes, the water can be cleaned with filtration systems, but in other cases, it may be rendered useless. Since much of the world's supply of drinking water comes from groundwater, this makes groundwater contamination a serious problem. Especially in a community which cannot afford to ship in clean sources of water, people may be forced to drink the contaminated groundwater, because there is no alternative.

The issue of groundwater contamination is one reason why artesian wells are so popular. Artesian wells are wells which have been sunk into confined aquifers, accessing water which is locked safely inside a layer of impermeable rock. The water from such wells tends to be pure, and sometimes very flavorful, thanks to the dissolved minerals from the surrounding rock.

Damaged septic systems can lead to groundwater contamination.
Damaged septic systems can lead to groundwater contamination.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Oh my god, I heard that sites where there used to be chemical factories or where there was a chemical accident before are completely contaminated.

The chemicals never disappear and get through the soil and reach groundwater even after many years. They say that there are such incidents all over the world. People are still getting sick after 25-30 years.

We are not careful enough when it comes to dealing with chemicals. We are not regulating these industries enough. The BP accident is probably the best one. Who knows for how many years the world will be affected by it.

The saddest part is that even unborn babies are affected by groundwater contaminants. They may be born with disease or mental problems because of the chemicals.


I remember in biology class, we were taught about what a great source groundwater is because it runs through so many layers of rocks and sediments. These layers are sort of like a filtration system.

This might have been true before, but I doubt this is the case anymore. Just the effects of global industrialization is enough to contaminate groundwater. Plus, the population of the earth is increasing and we are slowly using up sources of fresh water.

I just read that 80% of rural areas in India rely completely on groundwater and 50% of urban areas rely on it too. India is what, the second most populated nation in the world. That's a lot of people using groundwater!

I just don't think that there are many pure sources of groundwater available anymore.


My mom was a nurse for over thirty years. She tells me that in the 1950s, groundwater contamination was common. She saw breakouts of typhoid and cholera many times in her career. I think these illnesses happen when things like sewage get into groundwater.

I've also noticed that during war there is breakouts too. So the lack of burial of war victims and the damage and destruction to water and sewer lines must be contaminating groundwater. Aside from these extreme cases, I'm so glad that we are living in an era where these illnesses are less common.


enough information.

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