MCQs on Water Supply & Waste Water Engineering

 50 multiple-choice questions (MCQs) on Water Supply & Waste Water Engineering

Water Demand & Quality

1. Per capita water demand for an Indian city with full flushing system is generally assumed as:
   a) 70 LPCD
   b) 135 LPCD
   c) 210 LPCD
   d) 250 LPCD
   ✅ Answer: b)

2. Which factor does NOT affect per capita water demand?
   a) Industrial development
   b) Climate
   c) Quality of water
   d) Distance from river
   ✅ Answer: d)

3. The presence of nitrates in water indicates:
   a) Hardness
   b) Recent pollution
   c) Organic pollution
   d) Old pollution
   ✅ Answer: d)

4. The desirable limit of turbidity in drinking water as per BIS is:
   a) 1 NTU
   b) 5 NTU
   c) 10 NTU
   d) 25 NTU
   ✅ Answer: b)

5. Biological Oxygen Demand (BOD) is an index of:
   a) Physical pollution
   b) Chemical pollution
   c) Bacterial pollution
   d) Biodegradable organic matter
   ✅ Answer: d)

6. Which of the following is not a physical characteristic of water?
   a) Colour
   b) Taste
   c) Hardness
   d) Odour
   ✅ Answer: c)

7. Total hardness is expressed in terms of:
   a) Calcium chloride
   b) Magnesium chloride
   c) Calcium carbonate
   d) Sodium carbonate
   ✅ Answer: c)

8. Which is the most important parameter in assessing portability of water?
   a) pH
   b) Turbidity
   c) Pathogenic organisms
   d) Temperature
   ✅ Answer: c)

9. Chlorine demand is defined as:
   a) Amount of chlorine required to kill all organisms
   b) Amount of chlorine required for residual chlorine
   c) Chlorine added – residual chlorine
   d) Chlorine added × contact time
   ✅ Answer: c)

10. Alkalinity in water is mainly caused by:
    a) Calcium
    b) Magnesium
    c) Carbonates and bicarbonates
    d) Iron
    ✅ Answer: c)

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2. Treatment Processes

11. Coagulation in water treatment is used to remove:
    a) Dissolved solids
    b) Bacteria
    c) Fine suspended particles
    d) Hardness
    ✅ Answer: c)

12. Common coagulant used in water treatment:
    a) Alum
    b) Lime
    c) Chlorine
    d) Soda ash
    ✅ Answer: a)

13. Disinfection of water is done to remove:
    a) Turbidity
    b) Hardness
    c) Pathogens
    d) Algae
    ✅ Answer: c)

14. Most commonly used disinfectant in India:
    a) Iodine
    b) Bromine
    c) UV rays
    d) Chlorine
    ✅ Answer: d)

15. Sedimentation is a process to remove:
    a) Dissolved solids
    b) Suspended solids
    c) Micro-organisms
    d) Gases
    ✅ Answer: b)

16. In rapid sand filters, the filtering media is:
    a) Pebbles
    b) Coarse sand
    c) Fine sand
    d) Gravel
    ✅ Answer: c)

17. Backwashing is associated with which water treatment unit?
    a) Coagulation tank
    b) Sedimentation tank
    c) Filtration unit
    d) Disinfection chamber
    ✅ Answer: c)

18. Aeration of water is mainly done to remove:
    a) Dissolved oxygen
    b) Odour and gases like CO₂
    c) Suspended particles
    d) Micro-organisms
    ✅ Answer: b)

19. Slow sand filters are efficient in removing:
    a) Algae only
    b) Bacteria and turbidity
    c) Iron and manganese
    d) Hardness
    ✅ Answer: b)

20. pH value of neutral water is:
    a) 5
    b) 6
    c) 7
    d) 8
    ✅ Answer: c)

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3. Distribution System

21. Dead end system is also known as:
    a) Tree system
    b) Grid system
    c) Ring system
    d) Radial system
    ✅ Answer: a)

22. Which method is used to detect leakage in distribution pipes?
    a) Pressure gauge
    b) Water meter
    c) Sounding rod
    d) Leak detector
    ✅ Answer: d)

23. Valves used to control flow in distribution are called:
    a) Check valves
    b) Sluice valves
    c) Scour valves
    d) Air valves
    ✅ Answer: b)

24. Water hammer in distribution pipe is caused due to:
    a) Air lock
    b) Leakage
    c) Sudden valve closure
    d) Silt deposition
    ✅ Answer: c)

25. The main requirement of a good distribution system is:
    a) Leakage
    b) Low pressure
    c) Flexibility
    d) Pollution
    ✅ Answer: c)

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4. Sewerage System

26. The water carried by sanitary sewers is called:
    a) Wastewater
    b) Storm water
    c) Sewage
    d) Trade effluent
    ✅ Answer: c)

27. Self-cleaning velocity in sewers is generally:
    a) 0.25 m/s
    b) 0.6 m/s
    c) 1.0 m/s
    d) 2.0 m/s
    ✅ Answer: b)

28. Combined system is not preferred because:
    a) Cost is low
    b) Large diameter required
    c) No storm water removed
    d) Odour issues
    ✅ Answer: b)

29. The minimum diameter of sewer used is:
    a) 50 mm
    b) 75 mm
    c) 100 mm
    d) 150 mm
    ✅ Answer: d)

30. Which sewer section is most economical?
    a) Circular
    b) Oval
    c) Egg-shaped
    d) Rectangular
    ✅ Answer: c)

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5. Sewage Characteristics & Treatment

31. BOD of raw sewage is usually:
    a) 10-20 mg/l
    b) 100-300 mg/l
    c) 500-700 mg/l
    d) >1000 mg/l
    ✅ Answer: b)

32. Presence of sulphides in sewage causes:
    a) Acidic water
    b) Alkaline water
    c) Foul smell
    d) Milky appearance
    ✅ Answer: c)

33. Which of the following is a primary treatment process?
    a) Activated sludge process
    b) Grit chamber
    c) Trickling filter
    d) Oxidation pond
    ✅ Answer: b)

34. Sludge volume index is used to determine:
    a) Velocity of sewage
    b) Settleability of sludge
    c) Flow in sewer
    d) BOD level
    ✅ Answer: b)

35. Anaerobic digestion occurs in:
    a) Trickling filter
    b) Aeration tank
    c) Digestion tank
    d) Grit chamber
    ✅ Answer: c)

36. Which process is used for biological treatment?
    a) Sedimentation
    b) Coagulation
    c) Activated sludge
    d) Filtration
    ✅ Answer: c)

37. The major function of secondary treatment is to remove:
    a) Suspended solids
    b) Pathogens
    c) Organic matter
    d) Oil and grease
    ✅ Answer: c)

38. A manhole is generally provided at a spacing of:
    a) 10 m
    b) 30 m
    c) 100 m
    d) 300 m
    ✅ Answer: b)

39. Sewage should not be discharged into rivers without:
    a) Filtration
    b) Pre-chlorination
    c) Primary treatment
    d) Secondary treatment
    ✅ Answer: d)

40. Which of the following is not a biological treatment method?
    a) Trickling filter
    b) Oxidation ditch
    c) Septic tank
    d) Grit chamber
    ✅ Answer: d)

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6. Plumbing Systems

41. Trap is used in house drainage to:
    a) Increase pressure
    b) Maintain velocity
    c) Prevent foul gases
    d) Filter solid waste
    ✅ Answer: c)

42. A septic tank is usually designed for:
    a) 1 day detention
    b) 2 days detention
    c) 5 days detention
    d) 7 days detention
    ✅ Answer: b)

43. Soil pipe is used to carry:
    a) Rainwater
    b) Water from kitchens
    c) Human excreta
    d) Industrial waste
    ✅ Answer: c)

44. The pipe which carries only wastewater (not sewage) from bath and kitchen is:
    a) Soil pipe
    b) Waste pipe
    c) Vent pipe
    d) Anti-siphonage pipe
    ✅ Answer: b)

45. Diameter of vent pipe is generally:
    a) More than soil pipe
    b) Equal to soil pipe
    c) Less than soil pipe
    d) Same as main sewer
    ✅ Answer: c)

46. The connection between two pipes of unequal diameter is made using a:
    a) Tee
    b) Elbow
    c) Reducer
    d) Coupling
    ✅ Answer: c)

47. Anti-siphonage pipe is connected to the:
    a) Soil pipe
    b) Trap
    c) Main sewer
    d) Inspection chamber
    ✅ Answer: b)

48. The minimum gradient for house drainage is:
    a) 1 in 20
    b) 1 in 40
    c) 1 in 60
    d) 1 in 100
    ✅ Answer: d)

49. Waste pipe is connected to:
    a) Vent pipe
    b) Inspection chamber
    c) Soil pipe
    d) Grease trap
    ✅ Answer: c)

50. Which of the following does NOT belong to plumbing systems?
    a) Trap
    b) Tee
    c) Grit chamber
    d) Vent pipe
    ✅ Answer: c)