Environmental Engineering Questions and Answers – Water Demand


This set of Environmental Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Water Demand”.

1. The average quantity of water (in lpcd) required for domestic purposes according to IS code is ________
a) 100
b) 120
c) 70
d) 135
View Answer

Answer: d
Explanation: The average domestic water demand in India is 135 litres per capita per day. For developed countries, average domestic water demand is around 340 lpcd because they live a luxurious life.

2. The average consumption of water required in factories in lpcd is ___________
a) 10-15
b) 20-30
c) 30-45
d) 70-80
View Answer

Answer: c
Explanation: The average water consumption in factories is 30lpcd when no bathrooms are required and 45lpcd when bathrooms are required.

3. In which type of water demand, minimum average consumption of water takes place?
a) Domestic water demand
b) Industrial water demand
c) Institutional and commercial water demand
d) Fire demand
View Answer

Answer: d
Explanation: The minimum average water consumption takes place in fire demand. It accounts to 1lpcd which is very less but this water is required in very less duration.
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4. What is the minimum water pressure available at fire hydrants?
a) 80-100kN/m²
b) 100-150kN/m²
c) 40-60kN/m²
d) 150-200kN/m²
View Answer

Answer: b
Explanation: The minimum water pressure available at fire hydrants is 100-150kN/m2 i.e 10-15m of water head and it should be maintained for 4 to 5 hours.

5. Match list 1(calculation of fire demand) with list 2 (formulae) and select the correct answer using the codes given below.

List 1 List 2
A. Kuchling’s Formula 1) Q = 3182√P
B. Freeman’s Formula 2) Q = 1136[P/5 +10]
C. Buston’s Formula 3) Q = 5663√P
D. Central Congested High Value City 4) Q = 4637√P[1-.01√P]
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where Q = quantity of water, P = population in thousands
   A B C D
a) 1 2 3 4
b) 2 3 4  1
c) 2 1 4 3
d) 1 2 4 3
View Answer

Answer: a
Explanation: Kuchling’s formula is used when the population of the city exceeds 50,000.
When the population of the city is less than 2 lakh, the above formula for central congested high value city is used.

6. What is the fire demand of the city of 1lakh population by Buston’s formula?
a) 5663
b) 56630
c) 566300
d) 5663000
View Answer

Answer: b
Explanation: By Buston’s formula, Q = 5663√P where P in thousands. Here, P =100, Q = 5663√100 => Q = 56630.

7. Water lost in theft and waste contributes to how much % of total consumption?
a) 5
b) 10
c) 15
d) 20
View Answer

Answer: c
Explanation: Water loss in thefts and wastes contributes to 15% of total consumption, which includes the water loss due to leakage or stolen due to illegal connection.

8. Which is the correct statement regarding per capita demand?
a) Daily water required by an individual
b) Water required for various purposes by a person
c) Water required by an individual in a year
d) Annual average amount of daily water required by one person
View Answer

Answer: d
Explanation: The per capita demand is the annual average amount of daily water required by one person. It is denoted by q in litres per day per person.

9. What are the factors affecting per capita demand?
a) Size of city
b) Size of city, habit of people
c) Cost of water, quality of water, size of city
d) Cost of water, quality of water, size of city, habit of people
View Answer

Answer: d
Explanation: Increase in cost of water, quality of water and size of the city will result in more consumption of water. Poor habits of people in the utilization of water will also cause greater consumption.

10. Which of the following statement is correct?
a) Rich class consumes less water
b) Intermittent water supplies leads to less water consumption
c) Loss of water is more if the pressure in the distribution system is less
d) Water consumption is less in flush system
View Answer

Answer: b
Explanation: Rich class consumes more water, loss of water is more if the pressure in distribution system is more, water consumption is more in flush system and b option is the only correct statement.

11. If the annual average hourly demand of the city is 10000m3, what is the maximum hourly consumption?
a) 2700 m3
b) 27000 m3
c) 270000 m3
d) 2700000 m3
View Answer

Answer: a
Explanation: Maximum hourly demand = 2.7 * annual average hourly demand
= 2.7 * 10000
= 27000m3.

12. If in a city, the maximum daily draft is 25MLD, fire draft is 35MLD and maximum hourly draft is 40MLD, what is the coincident draft?
a) 60MLD
b) 40MLD
c) 25MLD
d) 35MLD
View Answer

Answer: a
Explanation: Maximum daily draft +fire draft = 25 + 35 = 60MLD
Maximum hourly draft = 40MLD
Coincident draft is maximum of maximum draft draft + fire draft and maximum hourly draft =60MLD.

13. What is the design period for the water treatment unit?
a) 10 years
b) 15 years
c) 20 years
d) 30 years
View Answer

Answer: b
Explanation: Water treatment unit is designed for 15 years and its design discharge is maximum daily demand.

14. What is the design discharge for intake structures?
a) Maximum daily demand
b) Maximum hourly demand
c) Maximum weekly demand
d) Average daily demand
View Answer

Answer: a
Explanation: Intake structures and the pipe mains that carry water from intake structures to treatment plant are designed for maximum daily demand.

15. In which of the following units, design period is maximized?
a) Distribution system
b) Demand reservoir
c) Water treatment unit
d) Pipe mains
View Answer

Answer: b
Explanation: Distribution system is designed for 30 years, the demand reservoir for 50 years, the water treatment unit for 15 years and the pipe mains for 30 years.
1 2 3 4
2 3 4 1
2 1 4 3
1 2 4 3

Sanfoundry Global Education & Learning Series – Environmental Engineering.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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