Potable Water

• What is potable water?

  Water that is safe to drink
• How can we obtain potable water?

  By treating fresh water sources or desalinating seawater
• What does it mean for water to be pure in chemistry?

  It contains only H2O molecules
• What are the three criteria for water to be considered potable?

  Low levels of dissolved substances, pH between 6.5 and 8.5, and no microorganisms
• Why is potable water often considered impure?

  It contains other dissolved substances
• What is the acceptable pH range for potable water?

  Between 6.5 and 8.5
• What types of microorganisms should be absent in potable water?

  Bacteria and fungi
• Where does the availability of potable water generally depend on?

  Where in the world you live
• What is fresh water?

  Water that doesn't have much dissolved in it
• What are examples of surface water sources?

  Lakes, rivers, and reservoirs
• How does the UK obtain its fresh water?

  From rain, which collects as surface water or groundwater
• What is the benefit of using surface water?

  It is easy to access and gets replaced frequently by rain
• What are groundwater sources?

  Water found under the ground, like aquifers
• What is a disadvantage of surface water in hot weather?

  It can dry up because it is exposed to the sun
• What is the first step in treating fresh water?

  Passing it through a wire mesh to filter out large particles
• What is the second step in the treatment of fresh water?

  Passing it through a bed of sand and gravel
• What are the three methods to sterilize water?

  Bubbling chlorine gas, exposing to ozone, or ultraviolet light
• What is desalination?

  A technique used to extract potable water from seawater
• What are the two techniques currently used for desalination?

  Distillation and reverse osmosis
• What is the final step in treating fresh water?

  Sterilizing it to kill harmful microbes
• Why is desalination considered a great idea?

  Because there is a limitless supply of seawater
• How does reverse osmosis work?

  Salty water is passed through a membrane that allows only water molecules to pass
• What do both distillation and reverse osmosis produce?

  Pure distilled water
• What is the process of desalination by distillation?

  Boiling large quantities of salty water and collecting the water vapor
• What are the methods of sterilizing water and their purposes?

  Methods:

  • Bubbling chlorine gas: kills bacteria
  • Exposing to ozone: kills microorganisms
  • Ultraviolet light: disinfects water
• What are the steps involved in treating fresh water to make it potable?

  1. Pass through a wire mesh to filter out large particles
  2. Pass through a bed of sand and gravel to filter smaller solids
  3. Sterilize to kill harmful microbes
• What are the advantages and disadvantages of using surface water versus groundwater for potable water supply?

  Advantages of surface water:

  • Easy to access
  • Frequently replenished by rain

  
  

  Disadvantages of surface water:

  • Can dry up in hot weather

  
  

  Advantages of groundwater:

  • Less likely to dry up
  • Often more protected from contamination

  
  

  Disadvantages of groundwater:

  • More difficult to access
• What are the challenges associated with desalination techniques?

  Challenges:

  • High energy requirements
  • Expensive processes
  • Impractical for large-scale production
• What is the difference between distillation and reverse osmosis in desalination?

  Distillation:

  • Involves boiling salty water and collecting vapor

  
  

  Reverse osmosis:

  • Involves passing salty water through a membrane to separate water molecules