Water pollution is the result of harmful particles entering bodies of water. This includes rivers, oceans, lakes, seas, groundwater, and human-built water systems. Water pollution endangers the aquatic ecosystem as well as plants and animals that live on solid ground. It also poses a very real threat to public health.

Causes of water pollution range from sources right in our homes, such as pills flushed down the toilet or our weekly laundry, to massive outputs from agriculture runoff and industrial waste. In order to prevent further water pollution, we need to identify the sources and act to eliminate them.

What are the main causes of water pollution?

Agriculture, commercial industries, transportation, and human wastewater all contribute to water pollution. Some sources of water pollution enter waterways directly. These sources include urban wastewater (sewage), wastewater dumped from industries, mariculture (fish farms), sludge from sourcing fossil fuel, and the shipping industry. These sources of water pollution are called ‘point sources’ because the pollution originates from one specific source.

Some sources of water pollution enter waterways through secondary means. This is often in the form of runoff. For example, chemicals spread on agricultural fields for fertilizer and pesticides will enter our water ways. Water from irrigation, rain, and rivers will carry the chemicals from the fields into the water system. Another example is oil, great, and chemical runoff from urban areas. These are ‘non-point sources’. Non-point sources are diffuse and more difficult to identify, making them more difficult to eliminate.

In order to better understand how water is so susceptible to pollution, let’s do a quick crash course on the water system. Let’s divide the natural water system into three sections: groundwater, surface water, and ocean water.

What is groundwater?

When it rains, rainwater makes its way downward through porous earth and crevices in the rocks. It collects in an aquifer. Some aquifers hold groundwater close to the Earth’s surface, while others are deeper than 30,000 feet below the surface. Groundwater is an essential resource – aquifers account for 30% of the world’s liquid freshwater.

Groundwater in aquifers becomes contaminated when the water picks up pollutants from agricultural fields and leached waste from septic systems and landfills. The process to remove pollutants from groundwater is difficult and expensive – sometimes even impossible. Once an aquifer is rendered unsafe, the groundwater within it may be unusable for decades to thousands of years.

What is surface water?

Surface water includes oceans, lakes, rivers, ponds, and streams. These bodies of water cover about 70% of the earth. Surface water houses vast and complicated ecosystems and provides us with much of the water we use on a daily basis.

Pollutants have reached even the deepest depths of surface water. Researchers found plastic in the Mariana Trench – a 30,000 foot deep trench that marks the deepest point of the ocean. Surface water suffers from both synthetic pollution and biological pollution. Synthetic pollutants include chemicals, plastics, and anything manmade. Biological pollutants include waste such as human sewage and some fertilizers used in farms,  yards, and landscaping.

Marine Pollution

Marine pollution is contamination of the ocean by harmful substances. A massive 80% of marine pollution comes from sources on land. Marine pollution also comes from pollutants in the air and wind-blown dust and debris.

What are the main effects of water pollution?

Water pollution affects life in the water as well as life on land in many ways. If the pollutant is of substantial size, say a plastic balloon let loose at a party, a plastic straw from a to-go cup, or even a plastic microfiber, marine life can entangle themselves or mistake it for food.

On a less visible but just as dangerous level, pollutants introduce toxins and drastically alter the nutrient levels of the habitat. Nutrient pollution is especially prevalent in freshwater sources. Runoff from agricultural fertilizers and waste carries large quantities of toxins, nitrates, and phosphates into bodies of water. Then, the nutrient imbalance can cause an overgrowth of algae – known as an algae bloom.

What is an algal bloom?

Algal blooms create a number of disruptions in marine habitats. Some algae blooms emit toxins which may cause illness and death for a range of animals including seabirds, turtles, fish and dolphins.

Shellfish can also absorb the toxins emit from an algae bloom. Animals who eat the affected shellfish can experience negative effects. Humans who eat shellfish tainted by an algae bloom can develop stomach illnesses and short-term memory problems. Humans who drink or come in direct contact with the algae can experience stomach aches rashes among a host of other problems.

Agricultural areas can experience a higher incidence of drinking water contaminated with excess nitrogen. This can be especially dangerous for infants 6 months old and younger. Treatment of contaminated water doesn’t eliminate the dangers. Some chemicals, such as chlorine, that are used to treat nutrient-polluted water have a reaction with the algae that creates by-products that are connected to developmental and reproductive health problems in humans.

Algal blooms also consume high amounts of oxygen. Oxygen is paramount for fish, shellfish, marine plantlife, and other organisms living in the marine habitat to survive. The threat of algal blooms doesn’t end there. Algal blooms can clog fish’s gills and make water cloudy, impairing predator’s ability to find food.

What are the common pollutants of water?

Chemicals, debris, and pathogens enter surface water from a number of point and non point sources. When rainfall is not absorbed through earth into aquifers, it becomes runoff and runs over the ground into bodies of water. Along its way, the water will pick up physical and chemical pollutants from its path. This includes fertilizers and pesticides from residential landscaping as well as agricultural fields. Runoff picks up oil and grease from roads and parking lots. Think of the small oil spot you’ve probably seen under your own car from time to time. Now realize that there are well over 1 billion vehicles in use worldwide. Runoff also collects heavy metals and chemicals from construction sites and industrial factories. These are all carried into bodies of surface water.

Pathogens are microorganisms that cause disease in human or animal hosts. This includes parasitic worms, viruses such as norovirus, salmonella, giardiasis lamblia, and more. These pathogens come from insufficiently treated sewage discharges, sanitation systems such as septic tanks in the surrounding environment, overflow of sewers due to weather, and livestock.

Other water pollutants come from chemicals we use in our daily lives. Detergents, soaps, pills flushed down the toilet, cleaning products, cosmetics, food waste like fats and grease, and fuels all end up in our water. There are even harmful chemicals created as a by-product of disinfecting water – chloroform is formed when water is disinfected for drinking.

How much plastic is there in the ocean?

Quite a bit! A professor of engineering at the University of Georgia, Jenna Jambeck, made a researched estimate in 2015 that between 5.3 million and 14 million tons enter the ocean every year – from coastal regions alone. Most of this staggering amount isn’t dumped directly into the ocean, but it is dumped on land or in rivers from where it inevitably ends up in the ocean. Since plastic takes hundreds of years to break down and some plastic doesn’t break down at all, every piece of plastic that has been made is still around. The plastic may be in smaller pieces than its original form, but it’s all still there.

In fact, as the plastic gets smaller, it becomes more dangerous for the ecosystem. Smaller pieces travel farther, are more pervasive, and are more likely to be eaten. Microplastics are small enough that even filter feeders mistake them for food. Among these filter feeders, oysters, water fleas, and common crabs have shown reproductive problems, decreased appetites, and death due to eating plastic. These little guys are the keystone to the entire marine ecosystem. If they are in danger, all marine life is in jeopardy.

Made with fossil fuels, plastic contains and leaches toxins. In addition to the toxins inherent in plastic, the substance absorbs environmental toxins. This happens at an increased rate in saltwater. Plastic has a tendency to absorb chemicals such as DDT and BPA. In a sense, plastic in the ocean act as chemical sponges. Unfortunately, these sponges are mistaken for food too often. They also make their way into our drinking water.

A study tested for plastic in drinking water in more than twelve countries across five continents. Microplastics were in 83% of the tap water sources tested. Numbers in the US were higher than the average. From tapwater sources tested in the US, 94% had microplastics – this included the tap of the EPA headquarters.

How can we prevent water pollution?

The first step to solving any problem is understanding it. Since you’re here with us, you’ve already started. The next step is to take action.

We need to tackle water pollution with a three-pronged approach. First, make changes in your daily habits. A few things you can do to start:

• Use biodegradable soaps and detergents for personal hygiene and cleaning your home.
• Eliminate plastics from your life as much as possible; use reusable bottles and bags.
• Use a microfiber catching laundry bag when washing your laundry – or better yet, eliminate synthetic clothes from your wardrobe.
• Say no to plastic straws.
• If you’re a smoker, keep an eye on your butt. Cigarette butts are now thought to be the most prevalent type of trash in waterways. Don’t flick ’em for the fish, dispose of them responsibly.

Next, we need to support brands and companies that employ sustainable methods. After all, a significant portion of pollution comes from industrial waste and byproducts.

Finally, tell your friends. Because again, the first step to solving a problem is understanding it.