Water Impurities | Civil Engineering Optional Notes for UPSC PDF Download

Water Impurities

Dissolved Solids

1. Calcium Bicarbonate (Ca(HCO₃)₂)

   • Soluble salt that does not cause turbidity.
   • Common in many water sources.

2. Iron Salts (Fe²⁺, Fe³⁺)

   • Dissolved iron can impart a pale yellow or green color.
   • Can cause discoloration on precipitation and deposits in water lines.

3. Copper Salts (Cu²⁺)

   • Can cause intense blue coloration.
   • Similar issues as iron with discoloration and deposits.

Suspended Solids

• Substances not completely soluble in water, causing turbidity.
• Commonly include particles like sand, silt, and organic material.

Table: Common Impurities Found in Fresh Water

Surface Water vs. Groundwater

Surface Water

• Characteristics: High turbidity, low to moderate dissolved minerals, high biological content, high temporal variability.
• Source: Runoff from rain or melting snow.
• Impurities: Includes suspended sand, silt, organic material, and eroded minerals.

Groundwater

• Characteristics: Low turbidity, high dissolved minerals, low biological content, low temporal variability.
• Source: Water percolating through porous terrains.
• Impurities: Primarily dissolved minerals from soil and rock layers.
  

Mineral Reactions in Groundwater

• Example: Groundwater reacting with limestone forms calcium and magnesium bicarbonate, which are soluble.
• Impact: Causes hard water, requiring treatment for industrial use, especially in cooling and boiler systems.

Groundwater often contains scale-forming solids, which need consistent treatment due to stable chemistry. Limestone formations (aquifers) store large amounts of water but result in hard water due to mineral dissolution.
By understanding the types of impurities in water and their effects, appropriate treatment methods can be selected to ensure water quality for various applications.