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
• What makes potable water impure?

  Presence of 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
• What determines the source of potable water in different regions?

  Geographical location and climate
• What is fresh water?

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

  Through rainfall that collects as surface or groundwater
• What are surface water sources?

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

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

  It is easy to access and replenished by rain
• What is a drawback of using 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?

  Bubbling chlorine gas, ozone, ultraviolet light
• Why do some countries rely on desalination?

  They have limited fresh water supply
• 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 a wire mesh
  2. Pass through sand and gravel
  3. Sterilize to kill harmful microbes
• What are the advantages and disadvantages of desalination techniques?

  Advantages:

  • Provides water in arid regions
  • Utilizes abundant seawater

  
  

  Disadvantages:

  • High energy consumption
  • Expensive to produce large quantities
• Explain how potable water is produced from fresh water


  Choose appropriate source of fresh water

  Such as rivers, streams, lakes, boreholes

  Pass throught filter beds which removes undisclosed solids

  Sterilise using chlorine, ozone or uv light

  Which destroys harmfull microbes