Ground Water Contamination Defined: Everything You Need to Know

Have you ever wondered just what’s in your water?

This is a question that crosses a lot of peoples’ minds now and then, but have you ever really stopped to research more about the contaminants and pollutants you can find in the water where you live?

Did you know some of them can be potentially very dangerous?

Whether you’ve looked into this matter before or you’re just digging up information for the first time, this article is here to help. Here, you’ll find out all about the most important type of pollution that affects the entire world: ground water contamination.

If you’ve never heard of contamination of ground water, don’t worry. You’ll be introduced to the idea from the most basic concepts all the way up to more intricate details. You’ll find out where groundwater comes from, why it’s important, and the many different sources of groundwater contamination in the United States and beyond.

By the time you’ve finished reading this article, you’ll be well acquainted with the contamination of groundwater and its causes, its meaning, and how it can be prevented or cleaned up. You’ll be better informed so you can make solid judgment calls about how you take care of waste in and around your home, and you’ll be better able to figure out how you can help clean up underground water contamination in your part of the world.

Read on for a crash course in groundwater from start to finish.

What is Groundwater?

Before you can learn the correct groundwater contamination definition, it’s a good idea to first understand what groundwater is. Although you might have heard the term thrown around here and there, you might not have ever heard it completely explained to you. Read through this section for a brief introduction to groundwater.

If you walk out into nature and look around, chances are eventually you’ll see some water in the form of a pond, lake, stream, river, or even the ocean. When those bodies of water are made of freshwater (as opposed to salt water like the ocean), they’re called surface water. This is simply water that exists at the surface of the planet. However, there’s more water than that lying below the earth’s surface, and that’s what we call groundwater.

contamination of ground water

Over 50% of the people in the United States rely on groundwater for their main or sole source of clean, fresh drinking water. It’s also widely used in the agricultural field to water crops and provide drinking water for animals. This water can be found below ground, filling the space between rocks, dirt, or sand. It moves slowly through this part of the earth, and eventually, it reaches surface water.

The soil, sand, or rock that contains groundwater is called an aquifer. The part of the earth where groundwater is present is called the water table, and it can be found a couple of layers down from the surface of the earth, although the depth may change from place to place. There are many ways to reach groundwater, but one of the most traditional is the drilling of wells. Although groundwater may seem well-protected because of its location, it’s actually quite easy for other substances to reach it, and this can lead to very fast pollution or contamination.

Where does Groundwater Come From?

Now that you know what groundwater is, you can learn about where it comes from. Groundwater’s presence in the world today is crucial to sustaining life and the environment, but understanding where it comes from might be more challenging than you may think. There is a process involved with groundwater, and when it’s left to work correctly without interruption from humans, it’s a cycle that keeps replenishing itself. Unfortunately, when pollution and overuse take place, this cycle doesn’t work as well as it should.

  • In order to understand where groundwater comes from, you first need to remember the aquifers mentioned in the previous section. Groundwater is held in these aquifers below the surface of the earth. This water slowly but surely trickles through the ground and eventually reaches surface water sources.
  • When groundwater filters into surface water, this is called discharging. Ideally, it discharges into rivers, lakes, and wetlands that rely on it as their only source of new, fresh water. However, when human intervention takes place, this process is interrupted, and these bodies of water can no longer receive groundwater discharge properly. This leads to the disappearance of the wetlands and drying up of water sources around the world.
  • Water that evaporates from surface water sources is carried by clouds in the form of rain or snow. When this rain falls on the land or snow melts and seeps into the soil, it recharges the groundwater all over again. The source of groundwater is basically the water and snow that falls from clouds, which in turn comes from surface water that is fed by groundwater. This creates a perfect loop that should be left to function as nature intended.
  • When groundwater is used up, it’s almost impossible to replace it. Water is dwindling resource, and groundwater is no different. When it’s gone, it’s gone, and surface water will soon suffer as well from a lack of groundwater to discharge into it.

How Important is Groundwater Anyway?

Okay, so you know what groundwater is, and you understand where it comes from. But just why is this something you need to be concerned with, anyway? Why is it so important that pollution prevention and cleanup efforts are so drastically focused on it now? You may be surprised to find out just how important groundwater really is, and what a difference it makes in the lives of people who rely on it for drinking water instead of using up surface water sources instead.

  • In rural parts of the United States, about 90% of the residents who live there rely completely on or almost completely on groundwater. Some of these areas include major cities that are populated with tens of thousands of people. This groundwater may be sourced by city and county utilities and private water companies that distribute it to their customers, or it may come from wells that have been drilled for an individual household house. Either way, the water comes from groundwater sources in these situations, and it sustains a lot of human life across the country.
  • Almost half of the water used for irrigation across the country comes from groundwater. Many of the crops grown in the United States would be completely impossible to grow (or to grow well) without irrigated groundwater. Unfortunately, this also puts a huge strain on groundwater sources and contributes significantly to overuse. Even so, these crops would dwindle quickly without the aid of groundwater to keep them thriving.
  • In places where the climate is very arid, groundwater may sometimes be the only option for water for plants, animals, and humans when drought takes place. Surface water dries up quickly during a drought situation, but it takes a while for groundwater to be affected. Of course, in a very serious drought, groundwater will still eventually dry up too, but it’s a much more stable source of water for a longer period of time in places where this happens.
  • 98% of domestic water use in 2005 came from groundwater sources, while 60% was used for raising livestock alone and 42% went toward irrigation. With numbers like these, it’s easy to see just how much the United States relies on groundwater every year.
  • Groundwater is just as widely used in much of the rest of the developed world. While developing countries still mostly rely on surface water to supply drinking water to their populations, developed countries are learning how to tap into groundwater sources across the world. This has both good and bad results.

Contaminants vs. Pollutants

So what is groundwater contamination exactly? In order to understand this, you’ll need to first find out the difference between pollutants and contaminants. They’re very similar, but they’re not exactly the same thing, and you need to be more concerned with one than you do with the other. In this section, you’ll have them both laid out for you in easy to understand terms so you can start recognizing groundwater pollution and contamination when you see it taking place.

what is groundwater contamination
  • Contaminants are substances present in water that aren’t part of the natural chemical makeup of water. This could be anything that you can find in a water sample. Even if you just look at a sample of water and see leaves or dirt floating in it, you’re seeing contaminants. Of course, they may also be chemicals and other things that can’t always be seen or even smelled by humans without scientific intervention.
  • Contaminants aren’t always dangerous. In the event of leaves or dirt floating in your water, for example, these contaminants aren’t exactly dangerous, especially in lower quantities. Many natural types of contaminants, like the animal waste in sources of untreated freshwater, can be very easily filtered away without too much trouble. These contaminants don’t pose a threat to human life or to the environment, so they aren’t dangerous.
  • Pollutants are also substances present in water that shouldn’t be. Just like contaminants, pollutants have no place being in a given water sample. They might also be visible or otherwise noticeable without laboratory testing, but not usually.
  • Pollutants are always dangerous in some way. Whether they are harmful to the environment, to human beings, or both, pollutants are always dangerous or present in quantities that are dangerous. This is what makes them pollutants instead of just contaminants.
  • A contaminant isn’t always a pollutant, but it can be. A pollutant is always a contaminant. When a contaminant crosses the line and becomes dangerous, then it is classified as a pollutant and should be avoided at all costs.
  • Sometimes, it takes laboratory studies to determine whether or not a substance is a contaminant or a pollutant. You might know that your water source has some chemicals in it, for example, but those chemicals might be there to help treat the water and actually make it safer to drink. Only laboratory testing can prove whether or not water treatment chemicals, for example, are present in levels that are too high and therefore become dangerous. This is true of many types of contaminants.
  • Most of the time, the classification of a substance in water depends on how much of it is present in any given water sample. Some contaminants aren’t a problem until they’re present in high quantities. Once again, it takes lab testing to figure this out, so it’s always important for water companies and providers to have their water tested on a regular basis.

Common Sources of Groundwater Pollution

Are you wondering just where groundwater pollution comes from? There are several different sources of this type of pollution, and wherever they are present, you’re likely to find polluted groundwater. You might also find groundwater that’s been contaminated but not necessarily polluted, although it’s always very likely that pollution is going to take place in these waters too. Below, you’ll find a list of common sources of groundwater pollution and a few sources of contamination too.

groundwater pollution
  • Septic and sewage systems – These are common contributors to the problem of groundwater contamination. Both septic and sewage systems rely on the placement of pipes to carry human waste away from homes, businesses, and other buildings. However, when these systems fail for any reason—even just due to a lack of maintenance—they develop cracks or leaks that allow human waste to seep into the surrounding soil. From there, it’s very easy for this to contaminate groundwater and lead to the spread of disease.
  • Chemical storage facilities Unfortunately, chemical storage facilities aren’t held to very high standards of maintenance or upkeep. Many of them are allowed to continue operating without regular assessments, or when these assessments are performed, they’re allowed to let many things slide. This leads to leaks and cracks that eventually allow very harsh and sometimes even potentially deadly chemicals to spread into the surrounding soil. This, too, leads to contamination of groundwater and pollution from chemicals that can do a lot of harm in a short amount of time.
  • Road salts and pesticides – Road salts and pesticides are both used in large quantities around the country every year. Especially in colder climates where freezing of roads is common, road salts pose a unique problem for groundwater. They don’t contaminate groundwater with anything dangerous, but they do raise the salinity of the groundwater in places where snow and ice have melted and carried the salts into the soil nearby. When this happens, groundwater carries this salt to surface water sources, and the increased salinity causes the death of fish and increased algal blooms. Pesticides cause a similar problem, and they also lead to serious algae problems in surface water. Sometimes, depending on the type of algae and the type of pesticide that caused it, these algal blooms can be toxic to humans and animals.
  • Landfills – It’s no secret that landfills contribute to just about every type of pollution on record. When people dispose of garbage inappropriately in landfills, they end up throwing away items that leak or otherwise seep into the soil and contaminate the groundwater in that area. Electronics and batteries are major proponents of this type of groundwater pollution. Plastics also cause pollution of groundwater and even surface water sources surrounding landfills. These products should always be recycled in dedicated recycling plants to avoid this type of pollution.
  • Hazardous waste spills and leaks – Of course, oil spills and other types of leaks of hazardous waste and chemicals cause groundwater pollution as well as surface water pollution. Although these events aren’t purposeful by any means, they still happen, largely because of human error or maintenance issues that could be prevented by stricter assessments or harsher punishments for these types of problems.
  • Natural contaminants – Especially in areas where mining is common, natural contaminants like lead and arsenic are widely present in groundwater. Although these come from rocks and from the earth itself, in high quantities, they are very dangerous and can lead to poisoning in humans, animals, and the environment.
  • Runoff – Runoff from construction sites, power plants, landfills, agricultural sites, and even residential communities can lead to groundwater pollution from chemicals used in all of these processes. When chemicals are present at these locations and it rains, stormwater carries the chemicals away from these sites and deposits it in the water table below the earth’s surface.
  • Factories – Factories cause toxic runoff as well, but they also pollute the groundwater in their areas through dumping. Although they often dump wastewater into surface water sources, sometimes they dump it on the soil instead, and this causes groundwater pollution from chemicals and other types of waste.

Why is Groundwater Pollution So Dangerous?

You probably have some idea why water pollution, in general, is a bad thing, but why is groundwater pollution so especially troubling? Groundwater is a vital part of our planet and, as such, we and much of the environment rely on it to help us survive and thrive. Below are some of the many ways groundwater pollution can seriously affect us all if it’s left untreated and without prevention.

  • Depleting wetlands – One of the biggest ways groundwater pollution can affect the environment is through causing the wetlands to disappear. These important ecosystems make up a huge part of the earth, and they were once very common in the United States. However, today, the wetlands are disappearing quickly because groundwater is simply not available to recharge them and keep them going strong.
  • Poisoning – Humans, animals, and plants can all be poisoned by groundwater pollution, depending on the pollutants present. When groundwater feeds into surface water sources that are used for drinking purposes, it carries pollutants into that water with it. If those pollutants are dangerous, like lead or arsenic, this can lead to widespread poisoning and very severe illness in all life in that area.
  • Algal blooms – Nitrate pollution is the leading contributing factor in algal blooms growing in freshwater surfaces, but this can come about from other causes as well. Wherever algal blooms get out of control, fish and insect life is choked out, and bird and mammal life in the area suffers because of a lack of food. This water may also become toxic to humans.
  • Waterborne illnesses – Especially in places where human waste is present in water supplies, waterborne illnesses are very common. This is a much bigger problem in developing countries than it is in developed ones, but that doesn’t mean it isn’t present sometimes in the United States too. Dysentery, hepatitis, stomach and digestive issues, and even some types of cancer can be caused by drinking water polluted with various types of contaminants.
  • Increased water strain – When groundwater is polluted, this puts a serious strain on the remaining sources of clean freshwater in the world. More people will turn to other sources of water, and that water will be used up much more quickly. Since water is a dwindling resource anyhow, this can be especially dangerous.
  • Decreased agricultural crops – Groundwater is used largely for agricultural purposes, so when it’s seriously polluted, crops and livestock both suffer. Crops may be seriously polluted or even poisoned because of polluted groundwater. This is how E. coli finds its way into vegetables and other food items on a regular basis, and in turn, this can lead to widespread illness if it isn’t caught in time.

What Are Some Major Groundwater Pollution Events?

In this section, you’ll find out about a few groundwater contamination cases that have taken place in the United States. You’ll discover what caused these events, why they affected the groundwater around the areas where they took place, and what’s being done to help improve the situation today. Remember that this is not a problem that affects the United States alone, however, and similar events have taken place all over the world.

1. Hinkley groundwater pollution

wastewater pollution

Between the years of 1952 and 1966, over 370 million gallons of wastewater polluted with chromium were dumped into water sources in and surrounding Hinkley, California. This mostly affected parts of the Mojave Desert, and although the dumping initially took place in surface water sources, groundwater was very quickly affected. To this day, the groundwater is so saturated with chromium that people who live in this area continue to be afraid of it in their drinking water supplies. It’s so present in the groundwater that it is still seeping into surface drinking water sources today, and Hinkley has been all but abandoned because of it. Chromium is known as a chemical that causes cancer.

2. Woburn groundwater pollution

pollution source

In the 1970s, leukemia became a huge problem in the town of Woburn, Massachusetts. This prompted studies of the water quality in the area, which turned up results of many chemicals present in the water. The contamination of the groundwater in the city’s drinking water wells came from chemical pesticides as well as from heavy metals naturally present in the surrounding environment, including zinc, arsenic, mercury, and chromium. All of these combined to create water that led to high levels of cancer and even death in the town. As soon as this was discovered, the wells were closed down, and they haven’t been used since. In the years since then, contaminated soil has been removed from five factory sites determined as the sources of this pollution.

3. Crestwood groundwater pollution

groundwater contamination

 The city of Crestwood, Illinois was the center of a groundwater contamination scandal as recently as 2009. The city promised to stop using a contaminated well for drinking water supplies in 1986 but continued to use it until 2007. This well was contaminated by chemicals used in dry cleaning services in the area, which were dumped and eventually found their way into the groundwater that fed into the well. These chemicals have been known to cause liver damage as well as other serious symptoms and even cancer. The water source is no longer being used, and many lawsuits were filed over illness and death that occurred from drinking this water for over twenty years. A cancer study showed an increased number of cancer patients in the Crestwood area.

How is Groundwater Pollution Being Addressed?

All hope is not lost! Even though groundwater pollution and contamination are on the rise, there are still plenty of things being done to make a difference. Depending on where you live, the local government might be a little more or a little less concerned with the state of groundwater in your area, but either way, there’s always something you can get involved with to help change things for the better. Here are just some of the ways groundwater pollution is being addressed in the United States today.

  • Clean Water Act – The Clean Water Act has been in effect since 1948, but in 1972 it began to grow into the serious of regulations it is today. This Act allows for the implementation of programs intended to help control the dumping of wastewater and other garbage into surface water sources. More recently, it’s also started to allow for stricter regulations against groundwater contamination through toxic runoff from factories, agricultural sites and more. This Act also makes it illegal to dump or allow pollutants to enter the water.
  • Local regulations – Depending on where you live, regulations may be very strict in terms of factories, construction sites, and agriculture, or they may be very lax. Unfortunately, in rural communities where agriculture is one of the largest sources of income and groundwater is used much more than surface water, regulations are usually not very strict at all. Enforcement of regulations may not be very strict in these places either.
  • Individual household changes – One of the best ways to address the problem of groundwater pollution is to stop it at its source in residential communities. More and more people are pitching now and helping prevent groundwater pollution by refraining from using harsh chemicals at home and making sure to dispose of waste properly. Recycling is also on the rise in these parts of the country, which leads to a decrease in landfill runoff over time too.
  • Improved assessments of water and storage sites – As groundwater’s importance becomes more and more obvious, counties and cities are performing better assessments of their water quality and of any chemical storage facilities in the area. The idea is to catch groundwater pollution before it gets too bad and to notice problem areas that might lead to leaks and spills before they happen.


Are you ready to get out there and make a difference? You might be surprised by what you’ve learned about groundwater contamination and pollution, but even though it may sound a little scary, don’t worry. The state of groundwater in the world today isn’t great, but it isn’t hopeless either. When more people like you become interested in making a difference and start taking steps to improve groundwater in different parts of the world, the situation will improve, even if it takes some time.

Now that you’ve learned what groundwater contamination is, where it comes from, and why it’s important, you can look at situations in your area and see if they seem to be contributing to the pollution of groundwater nearby. If you see a lot of factories operating without safe dumping of wastewater, for example, you might be able to speak to someone in a position of power in your community and start moving toward improving that.

Remember that there’s always something you can do to make a difference. Start by keeping harsh chemicals away from your household, and when you absolutely must use them for something, be sure to store them safely. Never throw away batteries or electronics in landfills, and be sure to recycle whenever possible. Even without speaking out to your community about groundwater, you can still make some changes for the better. Pretty soon, you might even find yourself feeling more comfortable about your cause to reach out to city leaders and see about making changes on a bigger scale.