Introduction to Sources of Water | Engineering Chemistry Notes

Introduction to Sources of Water

Water is one of the most important natural resources on Earth. In Engineering Chemistry, understanding the sources of water is crucial because its quality determines suitability for domestic, industrial, and engineering applications.

1. Classification of Sources of Water

• Surface Water
  • Rivers
  • Lakes
  • Ponds
  • Reservoirs and Dams
• Groundwater
  • Wells
  • Boreholes
  • Springs
• Rainwater (Atmospheric Water)
  • Rain
  • Snow
  • Dew

Figure: Schematic representation of sources of water

2. Characteristics of Different Sources

a) Surface Water

Usually contains suspended impurities (silt, clay, microorganisms) and dissolved minerals. Requires treatment (coagulation, filtration, disinfection) before use.

b) Groundwater

Filtered naturally through soil and rocks. Contains more dissolved salts (Ca²⁺, Mg²⁺, Fe²⁺, etc.) leading to hardness. Less contaminated with microorganisms compared to surface water.

c) Rainwater

Considered the purest form of natural water, but while falling through the atmosphere, it dissolves CO₂, SO₂, NO₂, etc., leading to acidity (acid rain). Collection and storage can introduce impurities.

3. Importance of Understanding Sources

• Design of water supply systems
• Determination of water treatment processes
• Assessment of pollution and contamination levels
• Engineering applications (concrete mixing, cooling, boiler feed water)

Typical Composition of Different Sources of Water

Source	Main Impurities
Surface Water	Silt, organic matter, microorganisms
Groundwater	Hardness-causing salts (Ca2+, Mg2+)
Rainwater	Dissolved gases (CO2, SO2, NO2)

Quick Revision Points

• Surface Water: Easily available, more microbial contamination.
• Groundwater: Naturally filtered, but hard due to dissolved salts.
• Rainwater: Purest, but can become acidic (acid rain).
• Engineering Relevance: Choice of source determines water treatment process design.

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