Groundwater is water beneath the surface of the earth, that has seeped down through soil layers above, through spaces in soil and fissures in stone, collecting in aquifers below the ground. This water naturally returns to the surface of the soil through springs and wetlands, and is replenished with rainfall.

For centuries, the active filtration of these layers of soil and stone were sufficient to purify the groundwater, making the water that emerged from springs clean and fresh. However, many human activities pollute the soil. These pollutants either seep down themselves into the aquifer or contaminate rain water as it penetrates the soil and are carried down into the groundwater. This can render the spring water unsafe for humans or animals to drink.

Groundwater contamination is generally used to refer to water that is unsafe to drink due to natural causes. Fluoride, arsenic, and nitrate are harmful natural compounds that can seep into groundwater. Contamination can also be caused by animal feces that may contain pathogens that filter into the water.

Groundwater pollution is generally used to refer to water that is unsafe to drink due to human activity. Fertilizers and pesticides, industrial leaks, sewage, and similar human activities all have a harmful effect on groundwater.

There are hundreds of potential causes and sources of groundwater pollution, large and small. Groundwater can get polluted through many of the daily activities that we may take for granted, such as:

In junkyards and auto repair shops, it's common for oil to be spilled or to leak gradually into the ground. In salting and de-icing, large quantities of salt or chemicals are sprayed onto roads and runways, where they leak into the ground as ice melts. Dry cleaning, photography, furniture refinishing, and medical care often involve specific solvents, chemicals, and compounds that can cause pollution when they aren't properly disposed of.

While all these factors contribute incrementally to groundwater pollution, the biggest contributors to large-scale groundwater pollution are:

Sewage and septic leaks. In places where sewage or septic facilities are inadequate or in poor repair, pathogens from human waste can seep into and pollute groundwater. Whether modern sewage treatment or septic systems develop a leak or discharge poorly-filtered materials into surface water, or whether less developed areas use pit latrines located near wells for drinking water, groundwater can get polluted by human waste and cause a variety of health issues, including skin lesions and dermatitis as well as intestinal problems.

Fertilizers and pesticides. Modern agricultural practices often include sweeping use of fertilizers and pesticides on acres of land at a time. Only a fraction of the nitrogen in fertilizers is used by the plants, leaving high levels of nitrate in the soil, potentially seeping down into the groundwater.

Often animal manure also contains residues of pharmaceuticals used in veterinary drugs, which can then enter groundwater. While many commercial pesticides have reduced risk of entering groundwater, the insecticide monocrotophos is persistent, soluble, and does not bind with minerals in soils, meaning that it can reach groundwater and potentially drinking water.

The effects of pesticides on groundwater are not well known due to the high cost of conducting analysis.

Commercial and industrial leaks. Mining and metal processing have both been shown to pollute groundwater, including increasing concentrations of arsenic. In addition, we store gasoline, oil, and chemicals in large underground tanks.

There are an estimated 10 million of these tanks in the United States, and they risk groundwater pollution in two ways: because they are underground, a leak may be undetected for longer than if the storage tanks were aboveground and visible. And because they are underground, potential leaks are closer to the water table, reducing the natural filtration of the aquifer.

Hydraulic fracturing. Hydraulic fracturing is the process of injecting high-pressure fluid to create cracks in deep rock formations. While there is debate about the degree to which fracking pollutes groundwater, with some studies finding elevated levels of methane, ethane, and propane gasses, as well as increased concentrations of helium and other noble gasses near fracking sites, the United States Environmental Protection Agency has not found evidence of a widespread, systemic impact on the quality of groundwater due to fracking.

Of potentially greater concern are the repeated spills of enormous volumes of fracking fluids at fracking sites, with major spills causing massive species deaths and home evacuations. Fracking fluid is generally made of water, solid materials, polymers, surfectants, friction reducers, biocides, and often radioactive tracer isotopes.

Controversially, hydraulic fracking fluid was specifically excluded from the 2005 American Clean Water Act, a decision believed to be due to lobbying from special interest groups.

While everyone can do their part to dispose properly of their household waste and chemicals, plant native plants, and conserve water, the truth is, the causes of groundwater pollution aren't due to the efforts and activities of most private individuals. If you want to prevent groundwater pollution, you have to get involved:

People have lived on, around, or near rivers for thousands of years. We have left a permanent mark on river ecosystems and in some case made them completely inhospitable.

River pollution happens when harmful substances come in contact with water. Centuries of improper waste management created and still create deposits of garbage on river beds. The industrial revolution and advancements in technology and transportation only made things worse.

Increased number of factories, poor environmental standards, and lack of proper legislation has made certain rivers in the world not only polluted but outright dangerous to be around. However, in the last few decades we can observe an increased awareness about the issue, and in some cases stricter regulations are being introduced and enforced.

You may think that the most polluted rivers in the world are located in developing countries. But you will be surprised to find out that river pollution exists in Europe, North and South America, as well as Asia and Africa. The only common denominator is human influence.

Ganges River

The Ganges runs for 1,569mi through India and Bangladesh. Not only is it one of the most sacred rivers for Indians, but the Ganges also represents a lifeline for millions of those whose daily needs depend on it. The environmental impact over the years has been devastating, by all accounts enough to make the Ganges the dirtiest river in the world.

Even though the Hindus believe the Ganges will cleanse them from sins, there is nothing clean about it. Human waste levels, or fecal coliform, are 100 times higher than the legal limit. The Hindus have been performing burial rituals in the Ganges, and if you combine that with rapid industrialization it is easy to understand why the Ganges is extremely polluted.

There were some conservation efforts, but little has been achieved. The authorities devised The Ganga Action Plan back in 1986, but due to corruption and lack of proper education and equipment it is considered a failure. We can only hope that future plans will yield a safer river ecosystem for almost half a billion people who use it every day.

Citarum River

Indonesia is the home of the Citarum River, and it is the longest and largest river in West Java. Java is the most populated Indonesian island, the site of Jakarta and other major cities, so around 200 million people share the areas around the Citarum River. There are also a great number of factories, which only makes the matter worse. The river has been used for everything from water supply, agriculture, industry, sewerage, and power supply.

The Citarum River landed on the list because of the fact that industries, primarily textile, contribute to major accumulation of toxic waste. The river contains lead, mercury, and arsenic. The levels of lead are 1000 times higher than the US legal limit. The combination of these factors is responsible for more than 50,000 deaths every year.

In the past decade, there were some efforts to improve the situation. The government set up a $3.5 billion plan to clean the Citarum River over the course of fifteen years. And, in 2009 an additional $500 million loan was secured by The Asian Development Bank. The revitalization began in 2011 and we can only hope that it will achieve the desired results.

Yellow River

The Yellow River got its name because of yellow sediment loess that gives it the distinct yellow color. It is the second longest river in Asia with an estimated length of 3,395mi. The Yellow River was very important to early Chinese civilization, but due to changing elevation and flooding it has earned nicknames like China’s Sorrow and Scourge of the Han People.

These nicknames are still applicable today, since the Yellow River has become one of the most polluted rivers in China. It is suggested that one third of the river is not suitable for industrial or agricultural use. The factors contributing to this are the fast-growing cities and factory discharges.

The Chinese government assembled the Yellow River Conservancy Commission which conducted a detailed investigation into the environmental problems. The results concluded that more than 33% of the river is unsuitable for any use. Additional conservation efforts are needed to prevent further pollution of the Yellow River.

Sarno River

Sarnus as it is known to the Romans, or the Sarno River, flows from the base of Mt. Sarno to the Bay of Naples. The Sarno River accumulates water from its two tributaries Solofrana and Cavaiola. Although its course runs for only 15mi it is arguably the most polluted river in Europe.

The good thing is that its source is not contaminated, and the water is safe for drinking. However, discharge from agriculture and industry has contributed to extreme pollution downstream. Poor sanitary standards and waste management, especially in the area around Naples, caused an increase in liver cancer cases.

Some preservation efforts have been made to protect the river and the ecosystems around it. A Padova University study outlined all of the problems, including detailed measurements at every part of what the researchers termed the “River Sarno fluvial corridor, and proposed a number of potential solutions. But, as of this writing, more things need to be done to remove the Sarno River from this list.

Buriganga River

The Buriganga River, or the Old Ganges, is located in Bangladesh and it flows near the outskirts of Dhaka, the capital of Bangladesh. The course of the Buriganga River is only 11mi long, but the number of people and industries that depend on the river make it one of the most polluted in the world.

There are plenty of pollution problems along the Buriganga River. They include chemical waste, household waste, medical waste, dead animals, and many more. However, the biggest polluter of the Buriganga River may be the tanning industry. It releases a great number of toxic chemicals directly into the river, causing an array of environmental and health hazards for the people working in the industry.

Residents of Dhaka organized a human chain in order to appeal to the authorities to improve the situation. Although the High Court of Bangladesh issued a verdict back in 2009, providing a legal framework for protection, the authorities have yet to properly enforce the legislation.

Marilao River

The Marilao River is located in the Philippines, and it has seen real battles in the Philippine-American War, as well as the battles to protect it from pollution. It is home to hundreds of thousands of people and a great number of industries. Most of the drainage is untreated and the factories release waste directly into the Marilao River without the use of water filters.

A lot of contamination comes from lead recycling facilities. Similar to the Buriganga River, the tanneries located along the Marilao River release untreated hexavalent chromium directly into the river. This pollutes the Manila Bay and seriously affects the fishing industry. There are reports that do a good job of outlining all of the hidden dangers and costs of the Marilao River pollution.

There are international projects that aim to clean and preserve the Marilao River, but they have been met by indifference from some of the locals. Since the people who live near the Marilao River believe that the pollution is the price they have to pay for economic progress.

Mississippi River

The Mississippi is the second longest river in the United States, stretching for 2,320mi from northern Minnesota to the Gulf of Mexico. It has been one of the most important lifelines in North America, and as such a home for millions of peoples. However, it is also the most polluted river in the US.

The Mississippi is brown because of all the wastes that are being dumped into the river. The main environmental dangers to the Mississippi River come from industries and agriculture. The aquatic life in the river has been seriously affected by nitrogen-based fertilizer which seeps into the water instead of remaining in the soil. In the past, oil spills were also one of the main pollutants of the Mississippi.

The positive thing is that in the past decades there has been an increased awareness about the pollution of the Mississippi River. There are numerous organizations and individuals who are contributing to the preservation of the Mississippi basin. And the EPA has been fairly good at enforcing the Clean Water Act.

Jordan River

The Jordan is a 156mi-long Middle Eastern river. Its source is in Mount Hermon and it flows into the Dead Sea. The Jordan River has a great cultural and religious significance to Christians and Hebrews. According to the legend, it is where the Israelites crossed into the Promised Land, and the place of Jesus’ baptism.

The water at its source is clean and can be used by humans. But, the level of toxicity increases as the water travels downstream. Poor waste management, as is the case with most of the other rivers on our list, is one of the primary causes of pollution in the Jordan River. The main issue is the increased salinity of the water which makes it unfit for human consumption.

Recently, another major contributor to the pollution is the number of refugees who found shelter along the banks of the Jordan River. The refugee crisis coupled with local population increases is worsening the pollution problems. However, steps are being taken by the international community to prevent the situation from escalating.

Matanza River

The Matanza River, or the slaughterhouse river, is located in Argentina and it marks the southern boundary of the Buenos Aires federal district. It runs for 40mi, and the course of the Matanza River is heavily canalized, particularly in the lower parts of the river. As you may have guessed, there are a great number of industries located along its banks, making it hard to protect the river.

Millions of tons of sewage are released into the Matanza River every day. Even worse is the fact that chemical factories deposit mercury and lead into the river, which has caused a spike of cancer cases in the region. The Matanza earned the nickname slaughterhouse river because of the numerous slaughterhouses and tanneries along its banks. They are also the reason for the river’s foul smell.

However, it is not all bad news. The World Bank reports that significant improvements have been made in cleaning and protecting the Matanza River. There projects to limit the discharge of sewage and industrial waste into the water and those that oxygenate the Matanza River to revitalize its ecosystem.

Yamuna River

The Yamuna River is the second largest tributary of the Ganges River. It originates from the Yamunotri Glacier and flows for 855mi before it meets the Ganges. Around 57 million people depend on the Yamuna River for the highly-fertile alluvial plains along its banks.

Although the land around the river is highly fertile, agriculture is one of Yamuna River’s main sources of pollution. Another thing contributing to its pollution, besides agriculture and industry, is poor raw-sewage management. New Delhi has a handful of functional sewage plants which increases the pH level of the Yamuna water.

Many are wondering if the Yamuna River can ever be saved. There have been initiatives led by prominent Indian intellectuals to clean up the river. The awareness of the problem seems to be great, but a more integrated, government-supported effort is needed to achieve long-term results.

We all need to make a joined effort to protect the rivers, or we may soon find the dirtiest river in the world in our backyard.

We hope that this list of the most polluted rivers in the world makes you aware of the great magnitude of river pollution. Prompt actions need to be taken, or we might find ourselves living in a Mad Max-like world very soon.

There is still some hope left, as evidenced by the conservation and recovery efforts on the Mississippi River, the reigning most polluted river in the US. So, in all seriousness and without virtue signals let us all join forces and protect our rivers before they are damaged beyond repair.

More than half of Americans regularly take prescription medication. Of those who take a prescription, most take four different medications a day. And these numbers are rising steeply: in 1997, Americans filled 2.4 billion prescriptions. In 2016, the number increased to a whopping 4.5 billion.

While modern drug therapies play an important role in overall health, and these medications save lives every day, there are also problematic side effects for the individual and the environment. After a person has used their medication and it's passed through their body, those pharmaceuticals go into our sewage and waste water, where they end up in the environment, and often in our drinking water. 

Drugs and their metabolites (substances formed as the body metabolizes a drug) enter our water supply in several ways:

• As residual amounts in sewage and waste water from the homes of those who are taking the pharmaceuticals
• As effluents and runoff from drug manufacturing and production facilities, particularly those that are poorly controlled and have little oversight
• As agricultural runoff from animal production facilities, where pharmaceuticals are present in the excreta of animals that receive them
• Some studies also show that people flush unused prescriptions down the toilet to dispose of them.

These are bioactive chemicals, designed to have pharmacological effects on a person, but have unintended effects in the environment and drinking water supply. Pharmaceuticals are controlled substances, after all, and not intended to be consumed by anyone other than a person with a demonstrated medical need.

The broad term “pharmaceuticals” also includes over the counter and personal care chemicals, ranging from vitamins and painkillers, to active ingredients in shampoos and cosmetics.

While these drugs have all be found in tap water, they are only present in trace amounts and at safe levels. However, the fact that these drugs are present at all is a cause for some concern, when you consider that they may be unintentionally taken by those for whom the drug poses a health risk, such as those with existing liver or bone marrow disorders, or by pregnant women.

The World Heath Organization has assessed drinking water in the UK, Australia, and the United States, and determined that the concentrations of pharmaceuticals in drinking water are below the level of dosage that would have a negative effect, and that adverse health effects in humans are “extremely unlikely”

However, human health risk from direct consumption of tap water is not the only risk from these high levels of pharmaceuticals. For example, according to the National Center for Biotechnology Information, there are a number of additional effects, including:

• Food plants irrigated with waste water can have enough carbamazepine metabolites and lamotrigine to have a clinical effect on a human when, for example, eating a carrot.
• Waste water from a hospital in Spain was found to contain enough ibuprofen to pose a risk to aquatic organisms.

Furthermore, this is a problem that will only get worse over time, as the levels of available fresh water decrease, and prescription medication usage continues to increase.

The biggest determinant of how much and what kind of pharmaceuticals end up in our drinking water is what kind of filtration methods are being used by the government or utilities that supply the water. Advanced countries usually employ several methods for treating and filtering water for human consumption, including:

• Granular activated carbon
• Membrane technologies
• Ozone treatments
• Ultraviolet radiation

But not all countries have the facilities to treat their drinking water with these methods, and, unfortunately, even with all these treatments, some compounds remain unaffected.

More work needs to be done by governments and regulators. However, there are several steps that consumers can take to prevent pharmaceuticals from getting into the water supply in the first place:

Following these steps will reduce the number of pharmaceuticals available in our waste water, protecting human health and the environment.