water

• drinking water

  water goes through a process so it can be cleaned:

  reservoir- stored until water is needed

  sedimentation - water stored in tanks solid particles settles to the bottom

  filtration - water passes through layers of sand particles removing smaller & smaller particles

  chlorination- bubbles in chlorine to kill bacteria
• desalination

  removed salt from sea water to create drinking water using a process of evaporation

  uses lots of energy to heat the water so it’s very expensive
• fluoridation of water

  added fluoride to water to prevent tooth decay 


  advantages

  reduce NHS cost

  reduce anasthetic given to children

  disadvantages

  against human rights

  class II poison

  can cause cancer in high amounts
• soft water

  advantages

  makes soap lather better

  leaves no scale in pipes

  cleaner clothes

  disadvantages

  contain more sodium ions -> sodium is linked to heart disease

  dissolves metals from pipes -> poisonous
• hard water

  advantages

  nice taste

  calcium compounds are good for bones

  coats pipes w calcium carbonate help prevent corrosion

  disadvantages

  coating develops into a scale -> must be removed to prevent blocking

  uses more soap
• removing hardness of water

  temp- removed by boiling water to create a deposite called limescale 


  permanent- uses ion exchange

  the water passes into a collum containing glass beads coated in sodium chloride

  calcium ions in water swap places with the sodium ions in the salt and removes hardness