Theory

• Water pollution is the contamination of water sources including rivers, lakes, oceans, aquifers and groundwater. It occurs when pollutants are directly or indirectly discharged into water without adequate treatment to remove harmful compounds.
• Indirect sources of water pollution include contaminants that enter the water from soils or groundwater and from the atmosphere via rain.
• The high concentration of impermeable surfaces in urban areas increases run-off from roads and can carry numerous pollutants such as oils, heavy metals, rubber and other vehicle pollution into waterways and streams.
• The reduction in water percolation can also affect the quantity and quality of groundwater. Storm water run-off in urban areas can overwhelm combined storm water and waste water treatment systems when high volume flows exceed treatment capacities.
• Causes of water pollution in urban areas

  • surface run-off carry contaminants
  • industrial waste
  • poorly treated sewage low in oxygen, high in bacteria
  • rubbish dumps can leak pollutants
  • air pollution leads to acid rain
• Consequences of water pollution - affects 1.2 billion people

  • heavy metals from industry results in birth defects
  • industrial waste damages aquatic animal health, causing immune suppression
  • microbial pollutants result in diseases such as cholera, a major cause of infant mortality in LICs
  • nutrients deplete oxygen in water, suffocating aquatic organisms
  • suspended particles reduce quality of sea water
• In most HICs, water quality improvement focuses on:

  • the construction of water-treatment facilities and waste water plants
  • regulations aimed at 'point source' polluters such as industries which discharge water pollution into receiving waters or sewer systems that flow into treatment plants
• Lack of money and inadequate technology in LICs have resulted in much lower water quality standards. Effective legislation is often absent and enforcement of pollution controls limited.
• Low-impact development (LID) is a storm water management approach that helps reduce run-off. Done through the use of vegetation and permeable surfaces to allow water to seep into the ground. This reduces pollutants by more than 90 per cent.
• Legislation, regulation and enforcement: Some cities charge polluters per unit or businesses given a maximum discharge
• Education and awareness: the more people who know about the causes and effects of pollution, the more likely they will be to avoid adding to the problem e.g. wet wipes and tampons down the toilet
• Appropriate technology, e.g. the omniprocessor boils sewage solids burned to produce steam for electricity