Potable Water

• What is potable water?

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

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

  It contains only $H_2O$ molecules
• Why is potable water often considered impure?

  It contains other dissolved substances
• What are the three criteria for water to be considered potable?

  Low dissolved substances, pH 6.5-8.5, no microorganisms
• 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 depend on?

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

  Water with low dissolved substances
• How does the UK obtain fresh water?

  From rain, surface water, and groundwater
• What are surface water sources?

  Lakes, rivers, and reservoirs
• What are groundwater sources?

  Water found under the ground, like aquifers
• What is the benefit of using surface water?

  It is easy to access and replenished by rain
• What is a disadvantage of surface water?

  It can dry up in hot weather
• What is the first step in treating fresh water?

  Filtering through a wire mesh
• What is the second step in treating fresh water?

  Passing it through sand and gravel
• What is the final step in treating fresh water?

  Sterilizing to kill harmful microbes
• What are the three methods to sterilize water?

  Chlorine gas, ozone, ultraviolet light
• What is desalination?

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

  Distillation and reverse osmosis
• What is the process of desalination by distillation?

  Boiling salty water and condensing vapor
• How does reverse osmosis work?

  Water passes through a membrane, separating ions
• What is the outcome of both desalination techniques?

  Pure distilled water
• What are the steps involved in treating fresh water to make it potable?

  1. Filter through wire mesh
  2. Pass through sand and gravel
  3. Sterilize to kill harmful microbes
• What are the advantages and disadvantages of using desalination for potable water?

  Advantages:

  • Provides water in arid regions
  • Utilizes abundant seawater

  
  

  Disadvantages:

  • High energy consumption
  • Expensive and impractical for large quantities