Short Notes: Environmental Engineering - Module I | Short Notes for Civil Engineering - Civil Engineering (CE) PDF Download

 Page 1


Module-1
Raw Water Source
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be 
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Water Consumption Rate
It is very difficult to precisely assess the quantity of water demanded by the public, since there 
are many variable factors affecting water consumption. The various types of water demands, 
which a city may have, may be broken into following classes:
Water Consumption for Various Purposes:
Types of Consumption Normal Range 
(lit/capita/day)
Average %
1 Domestic Consumption 65-300 160 35
2 Industrial and Commercial 
Demand
45-450 135 30
3 Public Uses including Fire 
Demand
20-90 45 10
4 Losses and Waste 45-150 62 25
Fire Fighting Demand:
The per capita fire demand is very less on an average basis but the rate at which the water is 
required is very large. The rate of fire demand is sometimes traeted as a function of population 
and is worked out from following empirical formulae:
Authority Formulae (P in thousand) Q for 1 lakh 
Population)
1
American Insurance 
Association
Q (L/min)=4637 VP (1-0.01VP) 41760
2 Kuchling's Formula Q (L/min)=3182 VP 31800
Page 2


Module-1
Raw Water Source
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be 
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Water Consumption Rate
It is very difficult to precisely assess the quantity of water demanded by the public, since there 
are many variable factors affecting water consumption. The various types of water demands, 
which a city may have, may be broken into following classes:
Water Consumption for Various Purposes:
Types of Consumption Normal Range 
(lit/capita/day)
Average %
1 Domestic Consumption 65-300 160 35
2 Industrial and Commercial 
Demand
45-450 135 30
3 Public Uses including Fire 
Demand
20-90 45 10
4 Losses and Waste 45-150 62 25
Fire Fighting Demand:
The per capita fire demand is very less on an average basis but the rate at which the water is 
required is very large. The rate of fire demand is sometimes traeted as a function of population 
and is worked out from following empirical formulae:
Authority Formulae (P in thousand) Q for 1 lakh 
Population)
1
American Insurance 
Association
Q (L/min)=4637 VP (1-0.01VP) 41760
2 Kuchling's Formula Q (L/min)=3182 VP 31800
3 Freeman's Formula Q (L/min)= 1136.5(P/5+10) 35050
4
Ministry of Urban 
Development Manual 
Formula
Q (kilo liters/d)=100 VP for P>50000 31623
Factors affecting per capita demand:
a. Size of the city: Per capita demand for big cities is generally large as compared to that 
for smaller towns as big cities have sewered houses.
b. Presence of industries.
c. Climatic conditions.
d. Habits of people and their economic status.
e. Quality of water: If water is aesthetically & medically safe, the consumption will increase 
as people will not resort to private wells, etc.
f. Pressure in the distribution system.
g. Efficiency of water works administration: Leaks in water mains and services; and 
unauthorised use of water can be kept to a minimum by surveys.
h. Cost of water.
i. Policy of metering and charging method: Water tax is charged in two different ways: on 
the basis of meter reading and on the basis of certain fixed monthly rate.
Fluctuations in Rate of Demand
Average Daily Per Capita Demand
= Quantity Required in 12 Months/ (365 x Population)
If this average demand is supplied at all the times, it will not be sufficient to meet the 
fluctuations.
• Seasonal variation: The demand peaks during summer. Firebreak outs are generally 
more in summer, increasing demand. So, there is seasonal variation .
• Daily variation depends on the activity. People draw out more water on Sundays and 
Festival days, thus increasing demand on these days.
• Hourly variations are very important as they have a wide range. During active 
household working hours i.e. from six to ten in the morning and four to eight in the 
evening, the bulk of the daily requirement is taken. During other hours the requirement is 
negligible. Moreover, if a fire breaks out, a huge quantity of water is required to be 
supplied during short duration, necessitating the need for a maximum rate of hourly 
supply.
So, an adequate quantity of water must be available to meet the peak demand. To meet all the 
fluctuations, the supply pipes, service reservoirs and distribution pipes must be properly 
proportioned. The water is supplied by pumping directly and the pumps and distribution system 
must be designed to meet the peak demand. The effect of monthly variation influences the 
design of storage reservoirs and the hourly variations influences the design of pumps and 
service reservoirs. As the population decreases, the fluctuation rate increases.
Maximum daily demand = 1.8 x average daily demand
Page 3


Module-1
Raw Water Source
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be 
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Water Consumption Rate
It is very difficult to precisely assess the quantity of water demanded by the public, since there 
are many variable factors affecting water consumption. The various types of water demands, 
which a city may have, may be broken into following classes:
Water Consumption for Various Purposes:
Types of Consumption Normal Range 
(lit/capita/day)
Average %
1 Domestic Consumption 65-300 160 35
2 Industrial and Commercial 
Demand
45-450 135 30
3 Public Uses including Fire 
Demand
20-90 45 10
4 Losses and Waste 45-150 62 25
Fire Fighting Demand:
The per capita fire demand is very less on an average basis but the rate at which the water is 
required is very large. The rate of fire demand is sometimes traeted as a function of population 
and is worked out from following empirical formulae:
Authority Formulae (P in thousand) Q for 1 lakh 
Population)
1
American Insurance 
Association
Q (L/min)=4637 VP (1-0.01VP) 41760
2 Kuchling's Formula Q (L/min)=3182 VP 31800
3 Freeman's Formula Q (L/min)= 1136.5(P/5+10) 35050
4
Ministry of Urban 
Development Manual 
Formula
Q (kilo liters/d)=100 VP for P>50000 31623
Factors affecting per capita demand:
a. Size of the city: Per capita demand for big cities is generally large as compared to that 
for smaller towns as big cities have sewered houses.
b. Presence of industries.
c. Climatic conditions.
d. Habits of people and their economic status.
e. Quality of water: If water is aesthetically & medically safe, the consumption will increase 
as people will not resort to private wells, etc.
f. Pressure in the distribution system.
g. Efficiency of water works administration: Leaks in water mains and services; and 
unauthorised use of water can be kept to a minimum by surveys.
h. Cost of water.
i. Policy of metering and charging method: Water tax is charged in two different ways: on 
the basis of meter reading and on the basis of certain fixed monthly rate.
Fluctuations in Rate of Demand
Average Daily Per Capita Demand
= Quantity Required in 12 Months/ (365 x Population)
If this average demand is supplied at all the times, it will not be sufficient to meet the 
fluctuations.
• Seasonal variation: The demand peaks during summer. Firebreak outs are generally 
more in summer, increasing demand. So, there is seasonal variation .
• Daily variation depends on the activity. People draw out more water on Sundays and 
Festival days, thus increasing demand on these days.
• Hourly variations are very important as they have a wide range. During active 
household working hours i.e. from six to ten in the morning and four to eight in the 
evening, the bulk of the daily requirement is taken. During other hours the requirement is 
negligible. Moreover, if a fire breaks out, a huge quantity of water is required to be 
supplied during short duration, necessitating the need for a maximum rate of hourly 
supply.
So, an adequate quantity of water must be available to meet the peak demand. To meet all the 
fluctuations, the supply pipes, service reservoirs and distribution pipes must be properly 
proportioned. The water is supplied by pumping directly and the pumps and distribution system 
must be designed to meet the peak demand. The effect of monthly variation influences the 
design of storage reservoirs and the hourly variations influences the design of pumps and 
service reservoirs. As the population decreases, the fluctuation rate increases.
Maximum daily demand = 1.8 x average daily demand
Maximum hourly demand of maximum day i.e. Peak demand
= 1.5 x average hourly demand 
= 1.5 x Maximum daily demand/24 
= 1.5 x (1.8 x average daily demand)/24 
= 2.7 x average daily demand/24 
= 2.7 x annual average hourly demand
Design Periods & Population Forecast
This quantity should be worked out with due provision for the estimated requirements of the 
future . The future period for which a provision is made in the water supply scheme is known as 
the design period.
Design period is estimated based on the following:
• Useful life of the component, considering obsolescence, wear, tear, etc.
• Expandability aspect.
• Anticipated rate of growth of population, including industrial, commercial developments & 
migration-immigration.
• Available resources.
• Performance of the system during initial period.
Population Forecasting Methods
The various methods adopted for estimating future populations are given below. The particular 
method to be adopted for a particular case or for a particular city depends largely on the factors 
discussed in the methods, and the selection is left to the discrection and intelligence of the 
designer.
1. Arithmetic Increase Method
2. Geometric Increase Method
3. Incremental Increase Method
4. Decreasing Rate of Growth Method
5. Simple Graphical Method
6. Comparative Graphical Method
7. Ratio Method
8. Logistic Curve Method
Population Forecast by Different Methods
Problem: Predict the population for the years 1981, 1991, 1994, and 2001 from the following 
census figures of a town by different methods.
Year 1901 1911 1921 1931 1941 1951 1961 1971
Page 4


Module-1
Raw Water Source
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be 
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Water Consumption Rate
It is very difficult to precisely assess the quantity of water demanded by the public, since there 
are many variable factors affecting water consumption. The various types of water demands, 
which a city may have, may be broken into following classes:
Water Consumption for Various Purposes:
Types of Consumption Normal Range 
(lit/capita/day)
Average %
1 Domestic Consumption 65-300 160 35
2 Industrial and Commercial 
Demand
45-450 135 30
3 Public Uses including Fire 
Demand
20-90 45 10
4 Losses and Waste 45-150 62 25
Fire Fighting Demand:
The per capita fire demand is very less on an average basis but the rate at which the water is 
required is very large. The rate of fire demand is sometimes traeted as a function of population 
and is worked out from following empirical formulae:
Authority Formulae (P in thousand) Q for 1 lakh 
Population)
1
American Insurance 
Association
Q (L/min)=4637 VP (1-0.01VP) 41760
2 Kuchling's Formula Q (L/min)=3182 VP 31800
3 Freeman's Formula Q (L/min)= 1136.5(P/5+10) 35050
4
Ministry of Urban 
Development Manual 
Formula
Q (kilo liters/d)=100 VP for P>50000 31623
Factors affecting per capita demand:
a. Size of the city: Per capita demand for big cities is generally large as compared to that 
for smaller towns as big cities have sewered houses.
b. Presence of industries.
c. Climatic conditions.
d. Habits of people and their economic status.
e. Quality of water: If water is aesthetically & medically safe, the consumption will increase 
as people will not resort to private wells, etc.
f. Pressure in the distribution system.
g. Efficiency of water works administration: Leaks in water mains and services; and 
unauthorised use of water can be kept to a minimum by surveys.
h. Cost of water.
i. Policy of metering and charging method: Water tax is charged in two different ways: on 
the basis of meter reading and on the basis of certain fixed monthly rate.
Fluctuations in Rate of Demand
Average Daily Per Capita Demand
= Quantity Required in 12 Months/ (365 x Population)
If this average demand is supplied at all the times, it will not be sufficient to meet the 
fluctuations.
• Seasonal variation: The demand peaks during summer. Firebreak outs are generally 
more in summer, increasing demand. So, there is seasonal variation .
• Daily variation depends on the activity. People draw out more water on Sundays and 
Festival days, thus increasing demand on these days.
• Hourly variations are very important as they have a wide range. During active 
household working hours i.e. from six to ten in the morning and four to eight in the 
evening, the bulk of the daily requirement is taken. During other hours the requirement is 
negligible. Moreover, if a fire breaks out, a huge quantity of water is required to be 
supplied during short duration, necessitating the need for a maximum rate of hourly 
supply.
So, an adequate quantity of water must be available to meet the peak demand. To meet all the 
fluctuations, the supply pipes, service reservoirs and distribution pipes must be properly 
proportioned. The water is supplied by pumping directly and the pumps and distribution system 
must be designed to meet the peak demand. The effect of monthly variation influences the 
design of storage reservoirs and the hourly variations influences the design of pumps and 
service reservoirs. As the population decreases, the fluctuation rate increases.
Maximum daily demand = 1.8 x average daily demand
Maximum hourly demand of maximum day i.e. Peak demand
= 1.5 x average hourly demand 
= 1.5 x Maximum daily demand/24 
= 1.5 x (1.8 x average daily demand)/24 
= 2.7 x average daily demand/24 
= 2.7 x annual average hourly demand
Design Periods & Population Forecast
This quantity should be worked out with due provision for the estimated requirements of the 
future . The future period for which a provision is made in the water supply scheme is known as 
the design period.
Design period is estimated based on the following:
• Useful life of the component, considering obsolescence, wear, tear, etc.
• Expandability aspect.
• Anticipated rate of growth of population, including industrial, commercial developments & 
migration-immigration.
• Available resources.
• Performance of the system during initial period.
Population Forecasting Methods
The various methods adopted for estimating future populations are given below. The particular 
method to be adopted for a particular case or for a particular city depends largely on the factors 
discussed in the methods, and the selection is left to the discrection and intelligence of the 
designer.
1. Arithmetic Increase Method
2. Geometric Increase Method
3. Incremental Increase Method
4. Decreasing Rate of Growth Method
5. Simple Graphical Method
6. Comparative Graphical Method
7. Ratio Method
8. Logistic Curve Method
Population Forecast by Different Methods
Problem: Predict the population for the years 1981, 1991, 1994, and 2001 from the following 
census figures of a town by different methods.
Year 1901 1911 1921 1931 1941 1951 1961 1971
Population: 60 65 63 72 79 89 97 120
(thousands)
Solution:
Year Population:
(thousands)
Increment per 
Decade
Incremental
Increase
Percentage Increment per 
Decade
1901 60 - - -
1911 65 +5 - (5+60) x100=+8.33
1921 63 -2 -3 (2+65) x100=-3.07
1931 72 +9 +7 (9+63) x100=+14.28
1941 79 +7 -2 (7+72) x100=+9.72
1951 89 + 10 +3 (10+79) x100=+12.66
1961 97 +8 -2 (8+89) x100=8.98
1971 120 +23 + 15 (23+97) x100=+23.71
Net values 1 +60 + 18 +74.61
Averages - 8.57 3.0 10.66
+=increase; - = decrease 
Arithmetical Progression Method:
Pn = P + ni
Average increases per decade = i = 8.57 
Population for the years,
1981= population 1971 + ni, here n=1 decade 
= 120 + 8.57 = 128.57
1991= population 1971 + ni, here n=2 decade 
= 120 + 2 x 8.57 = 137.14 
2001= population 1971 + ni, here n=3 decade 
= 120 + 3 x 8.57 = 145.71
1994= population 1991 + (population 2001 - 1991) x 3/10 
= 137.14 + (8.57) x 3/10 = 139.71 
Incremental Increase Method:
Population for the years,
1981= population 1971 + average increase per decade + average incremental increase 
= 120 + 8.57 + 3.0 = 131.57 
1991= population 1981 + 11.57 
= 131.57 + 11.57 = 143.14 
2001= population 1991 + 11.57 
= 143.14 + 11.57 = 154.71 
1994= population 1991 + 11.57 x 3/10 
= 143.14 + 3.47 = 146.61 
Geometric Progression Method:
Average percentage increase per decade = 10.66 
P n = P (1+i/100) n
Population for 1981 = Population 1971 x (1+i/100) n 
= 120 x (1+10.66/100), i = 10.66, n = 1 
= 120 x 110.66/100 = 132.8
Page 5


Module-1
Raw Water Source
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be 
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Water Consumption Rate
It is very difficult to precisely assess the quantity of water demanded by the public, since there 
are many variable factors affecting water consumption. The various types of water demands, 
which a city may have, may be broken into following classes:
Water Consumption for Various Purposes:
Types of Consumption Normal Range 
(lit/capita/day)
Average %
1 Domestic Consumption 65-300 160 35
2 Industrial and Commercial 
Demand
45-450 135 30
3 Public Uses including Fire 
Demand
20-90 45 10
4 Losses and Waste 45-150 62 25
Fire Fighting Demand:
The per capita fire demand is very less on an average basis but the rate at which the water is 
required is very large. The rate of fire demand is sometimes traeted as a function of population 
and is worked out from following empirical formulae:
Authority Formulae (P in thousand) Q for 1 lakh 
Population)
1
American Insurance 
Association
Q (L/min)=4637 VP (1-0.01VP) 41760
2 Kuchling's Formula Q (L/min)=3182 VP 31800
3 Freeman's Formula Q (L/min)= 1136.5(P/5+10) 35050
4
Ministry of Urban 
Development Manual 
Formula
Q (kilo liters/d)=100 VP for P>50000 31623
Factors affecting per capita demand:
a. Size of the city: Per capita demand for big cities is generally large as compared to that 
for smaller towns as big cities have sewered houses.
b. Presence of industries.
c. Climatic conditions.
d. Habits of people and their economic status.
e. Quality of water: If water is aesthetically & medically safe, the consumption will increase 
as people will not resort to private wells, etc.
f. Pressure in the distribution system.
g. Efficiency of water works administration: Leaks in water mains and services; and 
unauthorised use of water can be kept to a minimum by surveys.
h. Cost of water.
i. Policy of metering and charging method: Water tax is charged in two different ways: on 
the basis of meter reading and on the basis of certain fixed monthly rate.
Fluctuations in Rate of Demand
Average Daily Per Capita Demand
= Quantity Required in 12 Months/ (365 x Population)
If this average demand is supplied at all the times, it will not be sufficient to meet the 
fluctuations.
• Seasonal variation: The demand peaks during summer. Firebreak outs are generally 
more in summer, increasing demand. So, there is seasonal variation .
• Daily variation depends on the activity. People draw out more water on Sundays and 
Festival days, thus increasing demand on these days.
• Hourly variations are very important as they have a wide range. During active 
household working hours i.e. from six to ten in the morning and four to eight in the 
evening, the bulk of the daily requirement is taken. During other hours the requirement is 
negligible. Moreover, if a fire breaks out, a huge quantity of water is required to be 
supplied during short duration, necessitating the need for a maximum rate of hourly 
supply.
So, an adequate quantity of water must be available to meet the peak demand. To meet all the 
fluctuations, the supply pipes, service reservoirs and distribution pipes must be properly 
proportioned. The water is supplied by pumping directly and the pumps and distribution system 
must be designed to meet the peak demand. The effect of monthly variation influences the 
design of storage reservoirs and the hourly variations influences the design of pumps and 
service reservoirs. As the population decreases, the fluctuation rate increases.
Maximum daily demand = 1.8 x average daily demand
Maximum hourly demand of maximum day i.e. Peak demand
= 1.5 x average hourly demand 
= 1.5 x Maximum daily demand/24 
= 1.5 x (1.8 x average daily demand)/24 
= 2.7 x average daily demand/24 
= 2.7 x annual average hourly demand
Design Periods & Population Forecast
This quantity should be worked out with due provision for the estimated requirements of the 
future . The future period for which a provision is made in the water supply scheme is known as 
the design period.
Design period is estimated based on the following:
• Useful life of the component, considering obsolescence, wear, tear, etc.
• Expandability aspect.
• Anticipated rate of growth of population, including industrial, commercial developments & 
migration-immigration.
• Available resources.
• Performance of the system during initial period.
Population Forecasting Methods
The various methods adopted for estimating future populations are given below. The particular 
method to be adopted for a particular case or for a particular city depends largely on the factors 
discussed in the methods, and the selection is left to the discrection and intelligence of the 
designer.
1. Arithmetic Increase Method
2. Geometric Increase Method
3. Incremental Increase Method
4. Decreasing Rate of Growth Method
5. Simple Graphical Method
6. Comparative Graphical Method
7. Ratio Method
8. Logistic Curve Method
Population Forecast by Different Methods
Problem: Predict the population for the years 1981, 1991, 1994, and 2001 from the following 
census figures of a town by different methods.
Year 1901 1911 1921 1931 1941 1951 1961 1971
Population: 60 65 63 72 79 89 97 120
(thousands)
Solution:
Year Population:
(thousands)
Increment per 
Decade
Incremental
Increase
Percentage Increment per 
Decade
1901 60 - - -
1911 65 +5 - (5+60) x100=+8.33
1921 63 -2 -3 (2+65) x100=-3.07
1931 72 +9 +7 (9+63) x100=+14.28
1941 79 +7 -2 (7+72) x100=+9.72
1951 89 + 10 +3 (10+79) x100=+12.66
1961 97 +8 -2 (8+89) x100=8.98
1971 120 +23 + 15 (23+97) x100=+23.71
Net values 1 +60 + 18 +74.61
Averages - 8.57 3.0 10.66
+=increase; - = decrease 
Arithmetical Progression Method:
Pn = P + ni
Average increases per decade = i = 8.57 
Population for the years,
1981= population 1971 + ni, here n=1 decade 
= 120 + 8.57 = 128.57
1991= population 1971 + ni, here n=2 decade 
= 120 + 2 x 8.57 = 137.14 
2001= population 1971 + ni, here n=3 decade 
= 120 + 3 x 8.57 = 145.71
1994= population 1991 + (population 2001 - 1991) x 3/10 
= 137.14 + (8.57) x 3/10 = 139.71 
Incremental Increase Method:
Population for the years,
1981= population 1971 + average increase per decade + average incremental increase 
= 120 + 8.57 + 3.0 = 131.57 
1991= population 1981 + 11.57 
= 131.57 + 11.57 = 143.14 
2001= population 1991 + 11.57 
= 143.14 + 11.57 = 154.71 
1994= population 1991 + 11.57 x 3/10 
= 143.14 + 3.47 = 146.61 
Geometric Progression Method:
Average percentage increase per decade = 10.66 
P n = P (1+i/100) n
Population for 1981 = Population 1971 x (1+i/100) n 
= 120 x (1+10.66/100), i = 10.66, n = 1 
= 120 x 110.66/100 = 132.8
Population for 1991 = Population 1971 x (1+i/100) n 
= 120 x (1+10.66/100) 2 , i = 10.66, n = 2 
= 120 x 1.2245 = 146.95
Population for 2001 = Population 1971 x (1+i/100) n 
= 120 x (1+10.66/100) 3 , i = 10.66, n = 3 
= 120 x 1.355 = 162.60
Population for 1994 = 146.95 + (15.84 x 3/10) = 151.70
Intake Structure
The basic function of the intake structure is to help in safely withdrawing water from the source 
over predetermined pool levels and then to discharge this water into the withdrawal conduit 
(normally called intake conduit), through which it flows up to water treatment plant.
Factors Governing Location of Intake
1. As far as possible, the site should be near the treatment plant so that the cost of 
conveying water to the city is less.
2. The intake must be located in the purer zone of the source to draw best quality water 
from the source, thereby reducing load on the treatment plant.
3. The intake must never be located at the downstream or in the vicinity of the point of 
disposal of wastewater.
4. The site should be such as to permit greater withdrawal of water, if required at a future 
date.
5. The intake must be located at a place from where it can draw water even during the 
driest period of the year.
6. The intake site should remain easily accessible during floods and should noy get 
flooded. Moreover, the flood waters should not be concentrated in the vicinity of the 
intake.
Design Considerations
1. sufficient factor of safety against external forces such as heavy currents, floating 
materials, submerged bodies, ice pressure, etc.
2. should have sufficient self weight so that it does not float by upthrust of water.
Types of Intake
Depending on the source of water, the intake works are classified as follows:
Pumping
A pump is a device, which converts mechanical energy into hydraulic energy. It lifts water from a 
lower to a higher level and delivers it at high pressure. Pumps are employed in water supply 
projects at various stages for following purposes: