When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.
Water pollution has many sources. The most polluting of them are the city sewage and industrial waste discharged into the rivers. The facilities to treat waste water are not adequate in any city in India. Presently, only about 10% of the waste water generated is treated; the rest is discharged as it is into our water bodies. Due to this, pollutants enter groundwater, rivers, and other water bodies. Such water, which ultimately ends up in our households, is often highly contaminated and carries disease-causing microbes. Agricultural run-off, or the water from the fields that drains into rivers, is another major water pollutant as it contains fertilizers and pesticides.
Domestic sewage refers to waste water that is discarded from households. Also referred to as sanitary sewage, such water contains a wide variety of dissolved and suspended impurities. Biochemical oxygen demand, or BOD
The amount of organic material that can rot in the sewage is measured by the biochemical oxygen demand. BOD is the amount of oxygen required by micro-organisms to decompose the organic substances in sewage. Therefore, the more organic material there is in the sewage, the higher the BOD. It is among the most important parameters for the design and operation of sewage treatment plants. BOD levels of industrial sewage may be many times that of domestic sewage. Dissolved oxygen is an important factor that determines the quality of water in lakes and rivers. The higher the concentration of dissolved oxygen, the better the water quality. When sewage enters a lake or stream, micro-organisms begin to decompose the organic materials. Oxygen is consumed as micro-organisms use it in their metabolism. This can quickly deplete the available oxygen in the water. When the dissolved oxygen levels drop too low, many aquatic species perish. In fact, if the oxygen level drops to zero, the water will become septic. When organic compounds decompose without oxygen, it gives rise to the undesirable odours usually associated with septic or putrid conditions.

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It amounts to a very small fraction of the sewage by weight. But it is large by volume and contains impurities such as organic materials and plant nutrients that tend to rot. The main organic materials are food and vegetable waste, plant nutrient come from chemical soaps, washing powders, etc. Domestic sewage is also very likely to contain disease-causing microbes. Thus, disposal of domestic waste water is a significant technical problem. Sewage generated from the urban areas in India has multiplied manifold since 1947.
Today, many people dump their garbage into streams, lakes, rivers, and seas, thus making water bodies the final resting place of cans, bottles, plastics, and other household products. The various substances that we use for keeping our houses clean add to water pollution as they contain harmful chemicals. In the past, people mostly used soaps made from animal and vegetable fat for all types of washing. But most of today’s cleaning products are synthetic detergents and come from the petrochemical industry. Most detergents and washing powders contain phosphates, which are used to soften the water among other things. These and other chemicals contained in washing powders affect the health of all forms of life in the water.
What is the Cause of Water Pollution?
Water pollution refers to the changes in the physical, biological, and chemical conditions of any body of water which harmfully disrupts the balance of the ecosystem.
Like any type of pollution, water pollution results when an overwhelming amount of waste coming from different sources of pollutants can no longer be accommodated by the natural ecosystem. Consequently, when the wastes are not destroyed as fast as they are produced, they make it unfavorable to humans and many other organisms. But that’s not all. Learn more about what causes water pollution.
There are actually many specific reasons behind what causes water pollution. However, it is important to familiarize yourself with the two main categories of water pollution. Some pollution comes directly from one’s specific location. This type of pollution is called point source pollution such as sewage pipes that empty polluted water into the river and farmland. Meanwhile, non-point source pollution is pollution that comes from large areas like gasoline and other dirt from highways that go into the lakes and rivers.http://farm2.static.flickr.com/1068/1023347477_821ecbb29e.jpg
What are the causes water pollution? Who are the culprits who should be responsible for the harm brought by their pollutants? How do these sources of pollution pollute different bodies of water?
One major cause of water pollution that has caused serious environmental and health problems are the pollutants coming from chemical and industrial processes. When factories and manufacturers pour their chemicals and livestock wastes directly into streams and rivers, the water becomes poisonous and oxygen levels are depleted causing many aquatic organisms to die. These wastes include solvents and toxic substances. Most of the wastes are not biodegradable. Power plants, paper mills, refineries, automobile factories dispose waste into the rivers.
The heated water from the power plants is called thermal pollution. This kills aquatic animals and plants by reducing the oxygen content of the water. Power plants use water to cool their machineries, thus changing the temperature of the water.
Aside from thermal pollution, there are also organic and inorganic pollutants. The organic wastes include refuse from slaughter houses, fish and meat canning factories, and leather tanning companies, manufacturing plants, pesticides and crude oil companies. Since organic wastes are decomposed by microorganisms, much of the dissolved oxygen in water is used up and the waster begins to stink.
Inorganic wastes include toxic and corrosive substances like acids, heavy metals, mercury, cadmium and lead which can impair the normal body processes. Battery manufacturers, mining, paper mills increase the concentration of mercury making the water dangerous and poisonous for most living things.
Another cause of water pollution is from pesticides. Farm pesticides poison aquatic plants and animals. Animal manure, chemical fertilizers, phosphate detergent pollute water by supplying excess nutrients. This pollution is known as eutrophication. This greatly increases the growth of algae in water thereby decreasing the amount of oxygen level in water causing the death of many aquatic organisms.
Water is also being polluted by garbage specifically plastics and other plastic-like substances. Some plastic like nylon can entangle fishes and other marine animals. Plastics that have broken down into tiny pieces can be eaten by sea creatures which may cause their death. Since plastic is non-biodegradable, it will continue to kill more fishes.
One more cause of water pollution is sewage coming from households. Since no one wants to live in a polluted area, near a dumpsite or landfill, the wastewater and untreated sewage are carried away from the home polluting different bodies of water. Most developing countries practice this type of sewage disposal. Even modern countries carry poorly treated sewage to canals leading to major bodies of water. The danger is when the sewage pipes gets broken and waste contaminates the drinking water. When this happens, the breakage will open a wide array of water borne diseases that will surely pose peril to consumers.
Last among the causes of water pollution are personal care and household products. Shampoo, lotion, moisturizer, hair dye, bleach, laundry detergent, fabric softener, and many others contribute to water pollution. Human waste is not the only thing that goes to sewage. These products also join the wastewater to contaminate the streams, rivers, and lakes.
Although the world abounds with water, only three percent of it is potable. Included in the 3% source of potable water are the streams, spring, rivers, lakes, and waterfalls that are continuously being threatened and contaminated by the different factors that cause of water pollution. If the sources of water pollution are not controlled, this basic necessity will eventually become a rare commodity only a few can afford to have.
Agricultural Run off
Eutrophication
When fresh water is artificially supplemented with nutrients, it results in an abnormal increase in the growth of water plants. This is known as eutrophication. The discharge of waste from industries, agriculture, and urban communities into water bodies generally stretches the biological capacities of aquatic systems. Chemical run-off from fields also adds nutrients to water. Excess nutrients cause the water body to become choked with organic substances and organisms. When organic matter exceeds the capacity of the micro-organisms in water that break down and recycle the organic matter, it encourages rapid growth, or blooms, of algae. When they die, the remains of the algae add to the organic wastes already in the water; eventually, the water becomes deficient in oxygen. Anaerobic organisms (those that do not require oxygen to live) then attack the organic wastes, releasing gases such as methane and hydrogen sulphide, which are harmful to the oxygen-requiring (aerobic) forms of life. The result is a foul-smelling, waste-filled body of water. This has already occurred in such places as Lake Erie and the Baltic Sea, and is a growing problem in freshwater lakes all over India. Eutrophication can produce problems such as bad tastes and odours as well as green scum algae. Also the growth of rooted plants increases, which decreases the amount of oxygen in the deepest waters of the lake. It also leads to the death of all forms of life in the water bodies.
The use of land for agriculture and the practices followed in cultivation greatly affect the quality of groundwater. Intensive cultivation of crops causes chemicals from fertilizers (e.g. nitrate) and pesticides to seep into the groundwater, a process commonly known as leaching. Routine applications of fertilizers and pesticides for agriculture and indiscriminate disposal of industrial and domestic wastes are increasingly being recognized as significant sources of water pollution.
The high nitrate content in groundwater is mainly from irrigation run-off from agricultural fields where chemical fertilizers have been used indiscriminately.
Industrial effluents
Waste water from manufacturing or chemical processes in industries contributes to water pollution. Industrial waste water usually contains specific and readily identifiable chemical compounds. During the last fifty years, the number of industries in India has grown rapidly. But water pollution is concentrated within a few subsectors, mainly in the form of toxic wastes and organic pollutants. Out of this a large portion can be traced to the processing of industrial chemicals and to the food products industry. In fact, a number of large- and medium-sized industries in the region covered by the Ganga Action Plan do not have adequate effluent treatment facilities. Most of these defaulting industries are sugar mills, distilleries, leather processing industries, and thermal power stations. Most major industries have treatment facilities for industrial effluents. But this is not the case with small-scale industries, which cannot afford enormous investments in pollution control equipment as their profit margin is very slender.
Transport and chemical reactions of water pollutants
Most water pollutants are eventually carried by the rivers into the oceans. In some areas of the world the influence can be traced hundred miles from the mouth by studies using hydrology transport models. Advanced computer models such as SWMM or the DSSAM Model have been used in many locations worldwide to examine the fate of pollutants in aquatic systems. Indicator filter feeding species such as copepods have also been used to study pollutant fates in the New York Bight, for example. The highest toxin loads are not directly at the mouth of the Hudson River, but 100 kilometers south, since several days are required for incorporation into planktonic tissue. The Hudson discharge flows south along the coast due to coriolis force. Further south then are areas of oxygen depletion, caused by chemicals using up oxygen and by algae blooms, caused by excess nutrients from algal cell death and decomposition. Fish and shellfish kills have been reported, because toxins climb the foodchain after small fish consume copepods, then large fish eat smaller fish, etc. Each successive step up the food chain causes a stepwise concentration of pollutants such as heavy metals (e.g. mercury) and persistent organic pollutants such as DDT. This is known as biomagnification which is occasionally used interchangeably with bioaccumulation.http://feww.files.wordpress.com/2007/10/water-pollution.JPG
The big gyres in the oceans trap floating plastic debris. The North Pacific Gyre for example has collected the so-called “Great Pacific Garbage Patch” that is now estimated at 100 times the size of Texas. Many of these long-lasting pieces wind up in the stomachs of marine birds and animals. This results in obstruction of digestive pathways which leads to reduced appetite or even starvation.
Many chemicals undergo reactive decay or chemically change especially over long periods of time in groundwater reservoirs. A noteworthy class of such chemicals are the chlorinated hydrocarbons such as trichloroethylene (used in industrial metal degreasing and electronics manufacturing) and tetrachloroethylene used in the dry cleaning industry (note latest advances in liquid carbon dioxide in dry cleaning that avoids all use of chemicals). Both of these chemicals, which are carcinogens themselves, undergo partial decomposition reactions, leading to new hazardous chemicals (including dichloroethylene and vinyl chloride).
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Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great distances through unseen aquifers. Non-porous aquifers such as clays partially purify water of bacteria by simple filtration (adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity: however, in some cases, the pollutants merely transform to soil contaminants. Groundwater that moves through cracks and caverns is not filtered and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use natural sinkholes as dumps in areas of Karst topography.
There are a variety of secondary effects stemming not from the original pollutant, but a derivative condition. Some of these secondary impacts are:
Silt bearing surface runoff from can inhibit the penetration of sunlight through the water column, hampering photosynthesis in aquatic plants.
Thermal pollution can induce fish kills and invasion by new thermophilic species. This can cause further problems to existing wildlife.
EFFECTS OF WATER POLLUTION
The effects of water pollution are seen in Thermal, Heavy Metal, Agricultural regions and due to fertilizers, chemicals, oil and contaminated ground water.
Effects of Water Pollution
Effects of Run-off Pollution
Rain picks up dirt and silt and carries it into the water. If the dirt and silt settle in the water body, then these sediments prevent sunlight from reaching aquatic plants. If the Sun can’t reach the plants, these perish. These sediments also clog fish gills and smother organisms that live on the bottom of the body of the water.
Effects of Oil Pollution and Antifreeze
If oil is spilled on the water, the effects on the ecosystem and the components are harmful. Many animals can be annihilated in case they ingest oil. Oil contaminated prey may be a reason of death for many. If the oil coats the feathers of birds, these may die. Oil and antifreeze makes the water have a foul odor and there is a sticky film on the surface of water that kills animals. Oil is the most harmful pollutant in the water.
Contaminated Ground Water Effects
If contaminated water enters the ground, there may be serious effects. People may become very sick and there is a probability of developing liver or kidney problems and cancer or other illnesses.
Fertilizers and other chemicals
Nitrates in drinking water leads to diseases of infants that may lead to their death. Cadmium is a metal in sludge-derived fertilizer. This can be absorbed by crops. When people ingest this, they may cause diarrheal disorders, liver and kidney damage. The inorganic substances like mercury, arsenic and lead are the causes of pollution. Other chemicals can also lead to problems concerning the taste, smell and color of water. Pesticides, PCBs and PCPs are all poisonous to all sorts of life. Pesticides are used in farming, homes and forestry. PCBs are found as insulators in old electrical transformers. PCPs are found in products like wood preservatives.
Effects of Agricultural Water Pollution
Rain and irrigation water drains off cultivated land that has been fertilized and treated with pesticides, the excess nitrogen and poisons are mixed with it into the water supply. These pesticides are toxic and pollute the water in a different mode. Aquatic plants growth cause de-oxygenation of water and annihilate flora and fauna in a stream, lake and river. Fertilizers enhance the growth of bacteria that are in water and increase the concentration of bacteria to hazardous levels.
Effects of Thermal Water Pollution
Machinery in the industries are cooled with water from lakes and rivers. This water reaches the river in a heated state. This water decreases the ability of the aquatic system to hold oxygen and raises the growth of warm water species.
Effects of Heavy Metal Water Pollution
Heavy metals like lead, mercury, iron, cadmium, aluminum and magnesium are present in water sources. If these metals are present in the sediment, these reach the food chain through plants and aquatic animals. This causes heavy metal poisoning in case the level in the water is very high.
Some other effects of water pollution
In rivers, oceans and seas, water pollution effects flora and fauna in them. Further, the birds and animals that consume this contaminated food supply can perish. Blood diseases, nervous system disorders and heart diseases are some of the effects of water pollution. Many toxins in polluted water lead to cancer. Rarely, the body’s chromosomal makeup can be altered. Some of the less potent effects are skin lesions, vomiting and diarrhea.
The effects of water pollution are not only devastating to people but also to animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers. More seriously, contaminated water destroys aquatic life and reduces its reproductive ability. Eventually, it is a hazard to human health. Nobody can escape the effects of water pollution.
The individual and the community can help minimize water pollution. By simple housekeeping and management practices the amount of waste generated can be minimized.http://www.danharlow.com/blog/wp-content/uploads/2007/09/esa-ganesh-img1.jpg
GLOBAL WATER POLLUTION

Estimates suggest that nearly 1.5 billion people lack safe drinking water and that at least 5 million deaths per year can be attributed to waterborne diseases. With over 70 percent of the planet covered by oceans, people have long acted as if these very bodies of water could serve as a limitless dumping ground for wastes. Raw sewage, garbage, and oil spills have begun to overwhelm the diluting capabilities of the oceans, and most coastal waters are now polluted. Beaches around the world are closed regularly, often because of high amounts of bacteria from sewage disposal, and marine wildlife is beginning to suffer.
CONCLUSION
Clearly, the problems associated with water pollution have the capabilities to disrupt life on our planet to a great extent. Congress has passed laws to try to combat water pollution thus acknowledging the fact that water pollution is, indeed, a seriousissue. But the government alone cannot solve the entire problem. It is ultimately up to us, to be informed, responsible and involved when it comes to the problems we face with our water. We must become familiar with our local water resources and learn about ways for disposing harmful household wastes so they don¿½t end up in sewage treatment plants that cannott handle them or landfills not designed to receive hazardous materials. In our yards, we must determine whether additional nutrients are needed before fertilizers are applied, and look for alternatives where fertilizers might run off into surface waters. We have to preserve existing trees and plant new trees and shrubs to help prevent soil erosion and promote infiltration of water into the soil. Around our houses, we must keep litter, pet waste, leaves, and grass clippings out of gutters and storm drains. These are just a few of the many ways in which we, as humans, have the ability to combat water pollution. As we head into the 21st century, awareness and education will most assuredly continue to be the two most important ways to prevent water pollution. If these measures are not taken and water pollution continues, life on earth will suffer severely.
Global environmental collapse is not inevitable. But the developed world must work with the developing world to ensure that new industrialized economies do not add to the world’s environmental problems. Politicians must think of sustainable development rather than economic expansion. Conservation strategies have to become more widely accepted, and people must learn that energy use can be dramatically diminished without sacrificing comfort. In short, with the technology that currently
exists, the years of global environmental mistreatment can begin to be reversed. See full size imagehttp://coris.noaa.gov/glossary/runoff_186.jpg
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