"Water, water everywhere / Nor any drop to drink." For many people around the world this famous line from Samuel Taylor Coleridge's poem "The Rime of the Ancient Mariner" holds grim truth. Rather than the undrinkable sea water of Coleridge's poem, however, people drink, bathe and cook with contaminated water. Sadly, their water isn't safe to drink because of water pollution.
Sources of Water Pollution
Water pollution comes from point sources or non-point sources. Point sources include factories, sewage pipes and specific spills from pipelines or containers. These point sources have a specific source and can be identified and controlled. Regulation, legislation, monitoring and sewage treatment facilities in the U.S. have greatly reduced water pollution from point sources.
Point sources remain the leading sources of water pollution in other countries, however. An estimated 2 billion people around the world drink water contaminated by feces because no sewage control systems are available. In addition, some high-polluting industries are moving from higher income countries to countries with lower costs and fewer regulations.
Non-point sources, however, do not have a specific point of origin. Runoff from storms and melting snow carry fertilizers, pesticides, oil and gasoline, litter such as plastic bags and animal feces into storm drains, creeks, rivers, lakes and, ultimately, the ocean. In the United States, non-point source pollution has become the main cause of water pollution.
Read more about the kinds of things that pollute water.
Types of Water Pollution
Major types of water pollution around the world is caused by microbial pathogens (mostly disease-causing bacteria and viruses), nutrients from fertilizers and feces, heavy metals such as arsenic and mercury, chemicals from roads and industry, and litter. Heat pollution, especially near power plants, can severely impact local ecosystems.
Effects of Water Contamination on People
The combined effects of air, land and water pollution cause an estimated 7.4 million deaths around the world each year. An additional one million deaths occur due to direct contact with toxic chemicals.
In developing countries, more than 80% of untreated sewage contaminates creeks, rivers, lakes and coastal areas. In some developing countries as much as 95% of sewage remains untreated. As a result, more than 2 billion people must use water polluted with disease-carrying bacteria and viruses. In 2016, lower respiratory tract infections and diarrheal diseases ranked as the third and fourth leading causes of death around the world, respectively.
Respiratory Tract Infections
Lower respiratory tract infections (LRTI) include bronchitis, pneumonia, tuberculosis and bronchiolitis. These infections can be caused by viruses such as the flu and respiratory syncytial virus (RSV), bacteria like streptococcus and staphylococcus, fungal infections and mycoplasma (small organisms with characteristics of bacteria and viruses).
LRTI prevention includes washing hands frequently, not touching one's face with unwashed hands and cleaning and disinfecting surfaces. Treatment includes drinking lots of fluids. Unfortunately, water contamination makes these treatment and prevention methods impossible for many people.
In 2015, diarrhea caused 8.6% of deaths of children less than 5 years old. Although diarrheal diseases impact people, especially children, worldwide, areas with poor water quality, poor sanitation and lacking medical facilities remain at highest risk for diarrhea. Cholera, giardia and typhus occur most often where sanitary conditions are poor or nonexistent.
Impacts on Nature
Another effect of water pollution on human populations results from the impact of water contamination on nature. Bioaccumulation occurs as heavy metals like mercury move up through the food chain contaminate shellfish and fish like mackerel, tuna and sharks, exposing consumers to these toxic chemicals. Mercury poses higher health risks to children under 6 and to child-bearing women because it interferes with brain development.
Effects of Water Pollution in Nature
Nutrient pollution due to untreated sewage and fertilizers in runoff often leads to algal blooms in fresh and salt water. Small algal blooms provide food for fish and other aquatic organisms. Large algal blooms, however, deplete the dissolved oxygen in the water, leading to dead zones in aquatic systems.
An estimated 30% of water quality issues in the U.S. are caused by nutrient pollution. Dead zones due to oxygen depletion or eutrophication (too many nutrients due to runoff) range from local ponds to an estimated 7,700 square mile area in the Gulf of Mexico.
Oil Pollution in Water
Most of the oil pollution in the U.S. comes from the millions of drips from vehicles being washed into waterways. Oil floats on water, cutting off oxygen for plankton. Oil causes tissue damage in coral and coral larvae, causes heart defects in bluefin tuna larvae and other fish and even small amounts of oil impairs the ability of seabirds to fly, swim and dive for food. Beach stranding of sea turtles and dolphins increased after the 2010 Gulf oil spill, suggesting a relationship.
Litter, especially plastic, has become an increasing source of water contamination. From tangling to choking, plastics and other debris adversely impact animals ranging from sea gulls and shellfish to turtles and whales. Besides the physical dangers, plastics introduce toxins into the ecosystem as they decompose or when chemicals in the plastic leach out.
- National Geographic: Freshwater Pollution
- Natural Resources Defense Council: Mercury Sources
- Dictionary.com: Water, water everywhere,/Nor any drop to drink
- Natural Resources Defense Council: Water Pollution - Everything You Need to Know
- Inter Press Service: In Developing World, Pollution Kills More than Disease
- Institute for Health Metrics and Evaluation: Global Burden of Disease Study 2017
- Institute for Health Metrics and Evaluation: Despite Substantial Global Reduction in Diarrhea Deaths, Half a Million Children Still Die from Diseases Each Year
- Natural Resources Defense Council: Mercury Guide
- National Oceanic and Atmospheric Administration: Ocean Pollution
- Smithsonian Ocean: Marine Plastics
- Smithsonian Ocean: Gulf Oil Spill
About the Author
Karen earned her Bachelor of Science in geology. She worked as a geologist for ten years before returning to school to earn her multiple subject teaching credential. Karen taught middle school science for over two decades, earning her Master of Arts in Science Education (emphasis in 5-12 geosciences) along the way. Karen now designs and teaches science and STEAM classes.