potable water

• • potable water is water that has been treated or safe for drinking
  • potable water is not pure water because it contains dissolved impurities
• • potable water must have low levels of dissolved salts and microbes
  • dissolved salts can be harmful to humans
  • microbes can cause illness
• • in dry countries, there is a lack of rivers or lakes
  • so, fresh water cannot be produced
  • so, sea water must be treated by desalination to make potable water
• • destalination makes potable water from sea water
  • distillation and reverse osmosis are forms of destalination
• • it is easier to make potable water from fresh water rather than from sea water
  • removing large amounts of sodium chloride requires a lot of energy
• distillation:

  1. test PH of water
  2. test water for presence of sodium chloride using flame test and using dilute nitric acid
  3. heat sea water in flask until it boils
  4. steam produced and is pure water, cooled and condensed
  5. salt stays in flask
• • distillation requires a lot of energy to boil water and to condense steam
  • waste water is hard to dispose of sustainably
• reverse osmosis:

  • water is under high pressure and passed through membrane with pores
  • pores allow water molecules to pass through but prevent most ions or molecules
• • reverse osmosis requires expensive membranes and produces large volume of waste water