Potable water

• What is potable water?

  Water that is safe to drink, however it does contain dissolved substances in small amounts.
• What is pure water?

  Water that is free from impurities or contaminants
• Where does most of our potable water come from?

  Rain water which contains low levels of dissolved substances which collects in the ground in aquifers and lakes and rivers.
• How do you produce potable water?

  1. Choose a good source of freshwater
  2. Pass the water through filter beds to remove materials e.g. leaves and suspended particles.
  3. Sterilise the water to kill microbes (chlorine, UV, ozone)
• What is desalination?

  Reduces the levels of dissolved minerals down to an acceptable level for potable water. This is done in countries where freshwater is scarce and the only available water source is too salty to drink.
• What are the two ways of carrying out desalination?

  Using distillation, or to pass the water through membranes called reverse osmosis. These both reduce the levels of dissolved minerals, however they both require large amounts of energy which makes them expensive.