What is Water Pollution?
Water pollution occurs when waste, chemicals, or other particles create a body of water (i.e. rivers, seas, lakes) that is harmful to fish and animals that need water to survive. Water pollution can also disrupt and negatively impact the natural water cycle.
Natural Causes of Water Pollution
Sometimes water pollution can be caused by natural causes such as volcanoes, algal blooms, animal waste and silt from storms and floods.
Human Causes of Water Pollution
Much water pollution comes from human activities. Some of the anthropogenic causes include sewage, pesticides and fertilizers from farms, sewage and chemicals from factories, silt from construction sites and waste from humans.
Oil Spills
Some of the most famous water pollution incidents are oil spills. One was the Exxon Valdez oil spill, which occurred when an oil tanker hit a reef off the coast of Alaska and spilled more than 11 million gallons of oil into the ocean. Another bad oil spill was the Deepwater Horizon oil spill when an oil well explosion spilled more than 200 million gallons into the Gulf of Mexico.
Acid Rain
Air pollution can also have a direct effect on water pollution. When particles like sulfur dioxide are abundant in the air, they can combine with rain to produce acid rain. Acid rain can turn lakes acidic, killing fish and other animals.
Effects on the Environment
Water pollution can have disastrous effects on the environment.
Water pollution can reach the point where there is not enough oxygen in the water for the fish to breathe. Fish can actually suffocate!
Sometimes pollution affects the entire food chain. Small fish absorb pollutants, such as chemicals, into their bodies. Then the larger fish eat the smaller and also contaminated fish. Birds or other animals can eat larger fish and be harmed by pollutants. An example is the use of the insecticide (insecticide) DDT. When birds of prey eat infected fish, they lay eggs with thin shells. The number of birds of prey began to decrease until DDT was banned.
Sewage can also cause major problems in rivers. Bacteria in the water will use oxygen to break down the wastewater. If there is too much wastewater, the bacteria can consume so much oxygen that there won’t be enough left for the fish.
Water pollution from major events like acid rain or oil spills can completely destroy marine habitats.
Effects on Health
Clean water is one of the most valuable and important commodities for life on planet Earth. For more than a billion people on the planet, clean water is nearly impossible to obtain. Dirty and polluted water can make them sick and is especially difficult for young children. Certain bacteria and pathogens in water can make people very sick and possibly die.
Types of Water Pollutants
There are many sources of water pollution. Here are some of the main causes:
Wastewater – Even today, wastewater is dumped directly into rivers and streams in many parts of the world. Sewage can carry harmful bacteria that make people and animals very sick.
Waste from farm animals – Waste from large herds such as pigs and cows can enter water supplies through runoff from heavy rains and storms.
Pesticides and Herbicides – Pesticides are usually sprayed on crops to kill insects and herbicides are sprayed to kill weeds. These harsh chemicals can enter the water through runoff from rainstorms. They can also contaminate rivers and lakes through oil spills.
Construction, Floods and Storms – Alluvium from construction, earthquakes, floods and storms can reduce the oxygen content of the water and suffocate fish.
Factories – Factories often use a lot of water to process chemicals, keep engines cool, and wash things down. Used wastewater is sometimes discharged into rivers or seas. It can be full of contaminants.
What can you do to help?
Save water – Fresh, clean water is a precious resource. Don’t waste it! Take shorter showers, ask parents not to water the lawn, make sure the toilet doesn’t leak, and don’t let the faucet run.
Don’t use weed killer – Ask your parents if you can weed in the yard so they don’t need herbicides (a type of herbicide).
Scrape your clean plates in the trash and don’t pour grease down the kitchen drain.
Trash – Always pick up your trash, especially at the beach, lake or river.
Facts About Water Pollution
Soap from washing your car can run down the drain and contaminate the water.
Only about 1% of the water on Earth is freshwater. The rest is salty and you can’t drink it.
About 40% of rivers and lakes in the United States are too polluted for fishing or swimming.
The Mississippi River carries about 1.5 million tons of pollutants into the Gulf of Mexico each year.
Between 5 and 10 million people die each year from diseases related to water pollution.