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• Water pollution


  Water gets polluted when any undesirable substance, which is not a natural component of water, is discharged into water bodies. This causes dissolved oxygen depletion, and other undesirable changes in water, making it unfit for use.
• Example of water pollution

  • Used water from industries
• Types of water pollution

  • Industrial
  • Stormwater Runoff
  • Domestic
  • Grey water
  • Black water
  • Feces
  • Urine
  • Bathroom
  • Laundry
  • Kitchen
• Stormwater Runoff


  Water from streets, open yards, etc. after a rainfall event that runs through drains or sewers
• Industrial wastewater


  Liquid waste from industrial establishments such as factories, production units, etc.
• Domestic wastewater


  Wastewater from residences (homes), business buildings (e.g. hotels), and institutions (e.g. universities)
• Greywater


  Liquid waste from washrooms, laundries, and kitchens which do not contain human or animal excreta
• Blackwater


  Wastewater generated in toilets. Blackwater may also contain some flush water besides urine and feces (excreta)
• Night soil


  Urine and feces together
• Sewage


  The term used for blackwater if it ends up in a sewerage system
• Influent


  Wastewater that is yet to enter a wastewater treatment plant or liquid waste that is yet to undergo a unit process or operation
• Sludge


  A semi-solid slurry from a wastewater treatment plant
• Point source pollution


  Pollutants that belong to a single identifiable source. Any single identifiable source of pollution from which pollutants are discharged.
• Example of point source pollution


  • Pipe, ditch, ship
• Non-point source pollution


  Pollutants emitted from multiple scattered sources. It is often termed 'diffuse' pollution and refer to those inputs and impacts which occur over a wide area and are not easily attributed to a single source.
• Examples of non-point source pollution

  • Excess fertilizers, herbicides and insecticides from agricultural lands and residential areas
  • Oil, grease and toxic chemicals from urban runoff and energy production
  • Sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks
  • Salt from irrigation practices and acid drainage from abandoned mines
  • Bacteria and nutrients from livestock
• Potential sources of contamination for surface and ground water

  • Industries
  • Sewage and wastewater
  • Mining activities
  • Agriculture run-off
  • Marine dumping
  • Burning of fossil fuels
  • Facilities handling radioactive materials
  • Urban development and run off
• Classification of water pollutants

  • Chemical Pollutants
  • Physical Pollutants
  • Physiological Pollutants
  • Biological Pollutants
  • Groundwater pollution
• Organic pollutants


  Compounds that contain carbon atom and are mainly of biological origin. They are the oxygen depleting substances in water.
• Types of organic pollutants

  • Biodegradable organic pollutants
  • Non-biodegradable organic pollutants
• Biodegradable organic pollutants


  Organic materials which can be easily degraded by microorganisms. Most of the naturally occurring organic compounds (originated from plants and animals) are biodegradable.
• Examples of biodegradable organic pollutants


  • Proteins, fats, carbohydrates, alcohols, acids, esters, soaps etc.
• Non-biodegradable organic pollutants


  Organic materials which are resistant to biological degradation. Most of these are synthetic organics, which are of high concern.
• Examples of non-biodegradable organic pollutants

  • Pesticides (DDT, aldrin, dieldrin, endrin, endosulfan, lindane, toxaphene, mirex, heptachlor etc.), tannic acid, cellulose, and many of the organics associated with petroleum.
• Inorganic pollutants


  Inorganic acids, alkalis, salts, anions, cations, free chlorine, ammonia etc. They are added as a result of industrial effluents, sewage, household cleansers and surface run-off from urban and agricultural field etc. They affect the physical and chemical quality of water.
• The biochemical oxygen demand (BOD) is a measurement of the quantity of oxygen utilized in the respiration of bacteria to oxidize organic materials in sewage and for the subsequent metabolism (oxidation) of cellular components generated from wastes.
• The BOD is proportional to the amount of oxidizable organic material in the wastewater; the more oxidizable organic material, the greater the BOD.
• BOD level is used to quantify the "strength" of wastewater.
• Physical Pollutants


  Pollutants which deteriorate the physical parameters of water quality, including color, turbidity, suspended matter, radioactivity, froth and thermal pollutants.
• Thermal pollution


  Increase in temperature of water body due to discharge of heated water or wastewater into the watercourse. Waste heat is mainly discharged into water by nuclear and thermal power plants, and by industries involving water as coolant in industrial manufacturing. Increased water temperature leads to depletion of oxygen and increased respiration.
• Physiological Pollutants


  Pollution caused by the presence of some chemicals, including taste and odor.
• Taste


  Many chemical compounds are released by industrial waste, which impart unpleasant taste to the water.
• Odor


  Odor in water is mainly produced by presence of volatile organics or due to metabolites produced by microorganisms.
• Biological Pollutants


  Pollution due to introduction and growth of micro and macro-organisms in water body, which adversely affect the quality of water, human health and ecosystem. Various biological pollutants include bacteria, algae, weeds, viruses, protozoa and worms.
• Groundwater pollution


  Pollution of groundwater found underground in soil or under rock structures called aquifers. About 25% of the planet's overall fresh water supply is groundwater, while surface water stored in rivers, lakes and soil moisture accounts for less than 1%. Groundwater and surface water are often closely interconnected, so when surface water becomes polluted, groundwater can become contaminated as well.
• Factors affecting ground water pollution

  • Rainfall pattern
  • Depth of water table
  • Distance from the source of contamination
  • Soil properties such as texture, structure and filtration rate