Why this topic is important for ECET?
In ECET 2026 Civil, Environmental Engineering carries direct and scoring questions. One of the fundamentals is Sources of Water Supply, since water resource planning and treatment depend on understanding where water is obtained and its quality. Many objective questions test whether students can differentiate surface vs. ground water, their advantages, disadvantages, and suitability for drinking supply. Mastering this topic ensures quick, sure-shot marks.
📘 Concept Notes
1. Classification of Water Sources
- Surface Water Sources
- Rivers
- Streams
- Lakes
- Ponds
- Reservoirs & Dams
- Ground Water Sources
- Wells (dug, tube, bore)
- Springs
- Infiltration galleries
2. Surface Water
- Generally more exposed to pollution.
- Contains suspended solids, organic matter, microorganisms.
- Advantages: Easy availability, large quantity.
- Disadvantages: Requires more treatment (filtration, disinfection).
Example: A city near Krishna river uses it as the main drinking source, but must apply coagulation + chlorination.
3. Ground Water
- Naturally filtered through soil layers.
- Usually free from pathogens, less turbidity.
- May contain dissolved salts (hardness, iron, fluoride, arsenic).
- Advantages: Better bacteriological quality.
- Disadvantages: Pumping cost, limited yield, risk of chemical contamination.
Example: Bore wells in rural villages often provide potable water but may show high fluoride in Nalgonda (AP/Telangana).
4. Rainwater Harvesting
- Direct source from rainfall.
- Stored in tanks/reservoirs.
- Advantages: Low cost, sustainable.
- Disadvantage: Seasonal, needs storage.
5. Desalination (Special Source)
- Conversion of seawater to freshwater (reverse osmosis, distillation).
- Expensive, but used in coastal arid regions.
6. Criteria for Selection of Water Source
- Quantity → Should meet current & future demand.
- Quality → Minimum treatment required.
- Reliability → Consistent availability.
- Economics → Cost of development + treatment.
- Distance → Transportation & pumping feasibility.
⚙️ Formulas
Water Demand (Daily Per Capita):
Per Capita Demand:
Storage Requirement (for equalization):
Rainwater Harvesting Potential:
where
R = Rainfall (m),
A = Catchment area (m²),
C = Runoff coefficient.
🔟 10 MCQs
Q1. Which of the following is a surface water source?
a) Tube well
b) Lake
c) Spring
d) Bore well
Q2. Ground water generally has:
a) High turbidity
b) High dissolved salts
c) High suspended matter
d) Free from hardness
Q3. Which one requires maximum treatment before use?
a) River water
b) Well water
c) Spring water
d) Rainwater
Q4. The main disadvantage of ground water is:
a) High turbidity
b) Limited yield and hardness
c) High BOD
d) Easy contamination from surface
Q5. A city has population = 1 lakh, per capita demand = 150 LPCD. Find total daily demand in MLD.
a) 10 MLD
b) 15 MLD
c) 20 MLD
d) 25 MLD
Q6. Rainwater harvesting potential for 500 m² roof, 1000 mm rainfall, runoff coefficient = 0.8 is:
a) 200 m³
b) 400 m³
c) 500 m³
d) 800 m³
Q7. Which of the following has best bacteriological quality?
a) River water
b) Ground water
c) Lake water
d) Reservoir water
Q8. Desalination is mainly used for:
a) High turbidity removal
b) Softening of water
c) Conversion of saline water to fresh
d) Killing bacteria
Q9. If per capita demand = 120 LPCD, population = 50,000, total demand in MLD is:
a) 5
b) 6
c) 7
d) 8
Q10. The most important factor while selecting a source of water supply is:
a) Aesthetic appeal
b) Quantity, quality, and reliability
c) Cultural acceptance
d) Ground elevation
✅ Answer Key
| Q | Answer |
|---|---|
| 1 | b |
| 2 | b |
| 3 | a |
| 4 | b |
| 5 | b |
| 6 | b |
| 7 | b |
| 8 | c |
| 9 | b |
| 10 | b |
🧠 Explanations
- Q1: Lake is surface source, others are groundwater → (b).
- Q2: Ground water usually has dissolved salts → (b).
- Q3: River water most exposed to pollution → (a).
- Q4: Limitation of groundwater = yield and dissolved hardness → (b).
- Q5: Demand = 100000 × 150 / 1000 = 15 MLD → (b).
- Q6: V = R × A × C = 1 × 500 × 0.8 = 400 m³ → (b).
- Q7: Ground water filtered through soil, bacteriologically good → (b).
- Q8: Desalination removes salts from sea/brackish water → (c).
- Q9: Demand = 50,000 × 120 / 1000 = 6 MLD → (b).
- Q10: Primary criteria = quantity, quality, reliability → (b).
🎯 Motivation / Why Practice Matters
In ECET 2026 Civil, Environmental Engineering is high-scoring. Many students neglect “basic theory topics” like sources of water supply, but they are direct, one-line, formula-based questions. By practicing these regularly, you can answer within 10–15 seconds, boosting speed and confidence. These are the “sure-shot” marks that help you climb the rank list.
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