Water Supply MCQ Quiz - Objective Question with Answer for Water Supply - Download Free PDF

Explanation:

• To ensure reliability, pipelines and pumping systems are designed for the greater of Peak Hourly Demand or Coincident Draft — so the system will not fail even under the highest expected load.

• The distribution system of water supply is the network of pipelines that delivers water to consumers.

• It must be designed to handle fluctuating water demands — during different times of day, seasons, or emergencies.

 Additional Information

Peak Hourly Demand (A):

• The maximum water demand occurring during the most critical hour of the day.

• This often happens during mornings or evenings when residential and commercial use is at its highest.

• The system must handle this peak to avoid pressure drops or shortages.

Coincident Draft (B):

• It represents the simultaneous maximum water demands of various parts of the system (or zones).

• Different areas may have peak demands at the same time — the system must also handle this scenario.

Average Daily Demand:

• The average amount of water used per day.

• Used for estimating overall supply but not sufficient for designing pipelines and pumps, which must handle peaks.

Explanation:

Reflux Valve (Check Valve)

• Allows flow only in one direction — prevents backflow in pipelines.

• Commonly used in pumping systems to stop water from flowing backward when pumps are turned off.

• Essential in maintaining system efficiency and preventing contamination from reverse flow.

 Additional Information

Sluice Valve

• Controls the flow in the distribution system, particularly at pipe junctions and corners.

• Works like a gate to completely open or shut flow in a pipeline.

• Used for isolating sections of the water distribution network during maintenance or repair.

Pressure Relief Valve

• Protects the system from excessive pressure by releasing water when pressure exceeds safe limits.

• Helps in relieving water hammer and overpressure situations, preventing damage to pipes and fittings.

• Used in pressurized water systems and pump installations.

Scour Valve

• Installed at low points or dead ends of pipelines to drain out waste water, sediments, or debris.

• Helps in cleaning and maintenance of pipelines.

• Regular operation of scour valves ensures better water quality and prolongs pipe life.

Explaination:

• The Grid Iron system is commonly referred to as the Reticulation system in water supply engineering.

• It consists of a network of interconnected pipelines arranged in a grid pattern, allowing water to flow from multiple directions.

• This ensures uniform pressure, redundancy during pipe failures, and efficient water distribution to all areas.

Additional Information

Dead End System:

• Has a main pipe with several sub-branches ending without interconnections.

• Simple and economical but suffers from stagnant water at the dead ends and non-uniform pressure.

Radial System:

• Water flows radially from a central reservoir or pumping station.

• Used in cities with zoned layouts, allows easy isolation and maintenance.

Ring System:

• Water flows in a circular loop, improving supply reliability.

• Suitable for important urban areas but more costly than grid systems.

Concept:

Reservoir Yield:

• It means the quantity of water which can be withdrawn from storage in the reservoir. Reservoir yield is determined by the rate of flow of the stream into the reservoir, losses due to evaporation from the reservoir surface, and the volume of water impounded in the reservoir 
• It is the amount of water that can be supplied by the reservoir in a specified interval of time.
• The specified time interval may vary from a day for a small distribution reservoir to a month or year for large conservation reservoirs.
• If we say that three million cubic meters of water can be supplied from a reservoir in a year then its yield is 3000000 m3/year.
•  The yield of the reservoir is dependent upon the inflow and thus varies from time to time.

Firm yield.

•  It is also known as Safe yield.
•  It is the maximum quantity of water that can be supplied from the reservoir with full guarantee during the worst dry period.

 Design Yield.

• The critical period for a reservoir is generally considered when natural flow in the reservoir is minimum.
• Hence a lower value than the guaranteed yield or safe yield may be taken for design purposes.
• This yield whose value is smaller than the safe or firm yield is known as design yield.
•  The value of design yield for a reservoir to be used for water supply is taken less than the safe yield.
•  In the case of reservoirs used for irrigation purpose, the design yield may be taken slightly more than the safe yield as crops can tolerate some deficiency of water during the exceptionally dry season

A Secondary Yield.

• The quantity of water available more than safe yield is known as secondary yield.
• This yield is available during a period of high inflows.
• This secondary yield of the reservoir can be used either to generate extra hydroelectric power or for irrigation of extra lands.

Average Yield.

•  The arithmetic average of the safe yield and the secondary yield considered for a number of years is known as average yield.
•  The storage capacity of the reservoir and its yield are very much interdependent.
• The water is stored in the reservoir to fulfill the safe yield requirements.
• If the capacity of the reservoir is more it can certainly provide more water and hence yield is more.
• The reservoirs are designed to meet specific water demands.

Explanation:

Analysis of the Correct Option

Cast Iron (C.I.) Pipes and Their Joints: Cast iron (C.I.) pipes are widely used in water distribution systems, drainage systems, and sewerage systems due to their durability, corrosion resistance, and ability to withstand high pressure. These pipes require proper joints to connect them securely and ensure leak-proof functionality. Several types of joints are used in cast iron pipes, such as Tyton joints, flanged joints, spigot and socket joints, etc. However, not all types of joints are suitable or used for C.I. pipes.

The Simplex joint is not typically used in cast iron pipes. This type of joint is more commonly associated with other pipe materials or specific applications unrelated to cast iron. The design and functionality of Simplex joints do not align with the requirements and characteristics of C.I. pipes. Instead, the joints used for C.I. pipes are specifically designed to accommodate their material properties, such as rigidity and brittleness, while ensuring a secure and durable connection.

Reason for the Correct Answer:

• Material Compatibility: Cast iron is a brittle material, and the joints used for it must provide adequate flexibility and sealing to accommodate minor movements and pressure variations. Simplex joints do not offer the required compatibility for cast iron pipes.
• Design and Application: The design of Simplex joints is not suited for the structural and functional needs of C.I. pipes. They are more commonly used in systems involving other materials, such as plastic or specific types of metal, where their design can be effectively utilized.
• Seal and Leak Prevention: Joints for cast iron pipes, such as Tyton joints or spigot and socket joints, are designed to provide a robust seal to prevent leaks, which is not a characteristic feature of Simplex joints.

Important Information

To better understand the rationale, let us analyze the other options:

Tyton joint

• Tyton joints are widely used in cast iron pipes. These are push-on joints that incorporate a rubber gasket to ensure a leak-proof connection. The flexibility provided by the Tyton joint makes it suitable for accommodating minor movements and pressure variations in pipelines, which is essential for the durability and reliability of cast iron pipe systems.

Flanged joint

• Flanged joints are commonly used in cast iron pipes for specific applications, such as connections to valves, pumps, or other equipment. These joints involve bolted flanges and gaskets to provide a secure and leak-proof connection. They are particularly useful in situations where pipes need to be dismantled for maintenance or repair.

Spigot and socket joint

• Spigot and socket joints are one of the oldest and most commonly used joints for cast iron pipes. In this type of joint, the spigot end of one pipe is inserted into the socket (or bell) end of another pipe, and the joint is sealed with materials such as lead or rubber gaskets. This type of joint provides a secure and durable connection, making it suitable for a wide range of applications in water supply and drainage systems.​

Explanation:

The odour characteristic is used for classifying odour of a given water sample as per IS 3025 (part-5) 1983 as follows:

1. Degrees of sweetness

2. Degrees of pungency

3. Degrees of smokiness

4. Degrees of Rottenness

Concept:

The population after n^th decade by using Arithmetic mean Method is given as:

\({P_n} = P + N\bar X\)

Where

P is the Present Population

N is no of decades of which population is to be calculated

X̅ is the average increase in population.

Calculation

\(\bar X = \frac{{9,000\; + \;7,000\; + \;12,000}}{3} = 9333.333\)

The population at end of 2011 i.e. after 3 decodes from 1981.

\({P_{{g_{011}}}} = 1,28,000 + 3 \times 9333.333\)

\({P_{{g_{011}}}} = 1,56,000\)

Explanation:

Various methods for population forecasting as suitable for that city, considering the growth pattern, are as follows:

1. Arithmetical increase method:

• In this method assumed that the population is increasing at a constant rate.
• This method is suitable for a large and old city with considerable development.

2. Geometrical increase method (or geometrical progression method):

• In this method, the percentage increase in population from decade to decade is assumed to remain constant. 
• This method gives higher values and hence should be applied for a young and rapidly increasing city, but only for a few decades.

3. Incremental increase method:

• This method is a modification of arithmetical increase method and it is suitable for an average size town under the normal condition where the growth rate is found to be in increasing order.

4. Logistic curve method:

• This method is used when the growth rate of the population due to births, deaths, and migrations takes place under normal situation and it is not subjected to any extraordinary changes like an epidemic, war, earthquake or any natural disaster, etc.

The different type of Valves and their purpose is given below in tabulated form:

Explanation

The design life and design discharge for different units in raw water are given below:

Note that

MDD (Maximum Daily Demand) = 2 × ADD ( Average Daily Demand)

Concepts:

Altitude valves are installed in the supply line to elevated tanks, basins, or reservoirs.   

The purpose of this valve is to admit water into the elevated tank until a present level is reached and to close at that point to prevent overflow and also holding the reservoir/elevated tank level constant.

Additional Information

The other different type of valves and their uses is given below:

Explanation

Water Requirement with Respect to Population as follows:

Concept:

Various methods for population forecasting as suitable for that city, considering the growth pattern, are as follows:

1. Arithmetical increase method:

• In this method assumed that the population is increasing at a constant rate.
• This method is suitable for a large and old city with considerable development.

2. Geometrical increase method (or geometrical progression method):

• In this method, the percentage increase in population from decade to decade is assumed to remain constant. 
• This method gives higher values and hence should be applied for a young and rapidly increasing city, but only for a few decades.

3. Incremental increase method:

• This method is a modification of the arithmetical increase method and it is suitable for an average size town under the normal condition where the growth rate is found to be in increasing order.

4. Exponential curve method

• It is a suitable method of estimating the future population by the end of the design period of the water supply scheme for a town or a city.

Concept:

Maximum hourly consumption:

It is generally taken as 150% of its average.

Therefore, maximum hourly consumption of the maximum day i.e. peak demand = 1.5 × average hourly consumption of maximum daily demand

= 1.5 × (maximum daily demand/24)

= 1.5 × (1.8 × annual average daily demand)/24

= 2.7 × annual average hourly demand

Calculation:

Given, 

Annual average daily demand = 48000 cubic meter

Maximum hourly demand = 2.7 × 48000/24 = 5400 cum/hour

Explanation:

IS 1172: 1993 is used for the basic requirements for water supply, drainage and sanitation

Important Points IS 456: 2000 - PLAIN AND REINFORCED CONCRETE - CODE OF PRACTICE 

IS 1035 (Part 32): Methods of Sampling and Test (Physical & Chemical) for water and wastewater

IS 10500 (2012): DRINKING WATER - SPECIFICATION

Additional InformationFrom IS 1172 (1993):

The following rates per capita per day may be considered the minimum for domestic and non-domestic needs:

1. For communities with a population of up to 20,000 and without a flushing system : 

a) water supply through standpost: 40 lpcd ( Min ) 

b) water supply through house service connection:  70 to 100 lpcd 

2. For communities with a population of 20,000 to 100,000 together with a full flushing system: 100 to 150 lpcd 

3. For communities with a population above 100000  together with a full flushing system: 150 to 200 lpcd