States of matter - potable water

• Sources of potable water

  • Sea water
  • Water contaminated by a human process
  • Rivers
  • Aquifiers
  • Lakes
  • Ground water
  • Surface water
• Treating waste water to make it potable

  1. Preferable to disposing of the water which could pollute the environment

  2. Depends on how easy/costly it is to treat based on type/levels of contaminants

  3. Can be done by simple distillation which is expensive in terms of energy required

  4. Condensation produces pure water
• Potable water is only carried out in countries that have abundant sea water or no other water sources, and have cheap energy resources
• Contaminants in fresh water sources

  • Objects such as leaves/twigs
  • Bacteria and other microorganisms
  • Soluble substances like salts/pesticides/fertilisers
  • Small insoluble particles like silt/sand
• Water treatment process


  1. Screening to remove twigs/leaves

  2. Sedimentation using iron/aluminium sulfate to clump fine particles

  3. Filtration through sand/gravel bed to remove smaller insoluble particles

  4. Chlorination to kill harmful microorganisms
• Cheaper option than simple distillation in terms of energy required
• Deionised water


  Water with dissolved ions removed by chemical process, pure water
• Distilled water


  Water isolated by simple distillation, pure water
• If water contains dissolved salts/ions, it may give false results or interfere with chemical analysis and produce precipitates