water supply

1. Subject: W.S.S.E.(3350603)
Topic: Suitability selection of source and criteria
considered for water supply.
prepared by: Bhavesh Hathila

2. Index
Introduction
Suitability of water
Selection of source of water supply
Criteria considered for water supply scheme

3. Suitability of water
1. Suitability of surface water
• With regard to quantity: rainfall directly affects
the quantity of surface water. As the rainfall is not
uniform throughout the year, the quantity of
surface water also have large variations. the
discharge in rivers and streams remains in
maximum in rainy season and minimum in
summer . If the quantity of water in summer is not
sufficient to meet the demand . It should be stored
in impounded reservoirs

4. • With regard to quality: surface water mostly
connection large amount of impurities in both
suspended and dissolved from. Surface water is
contaminated by the impurities while travelling
on the ground. While flowing on the ground it
will collect lot of silt, clay floating matter like
plant leaves, branches of trees, etc. The suspended
impurities contain disease producing bacteria's.
algae and other microorganisms, therefore,
surface water should not be used before treatment.

5.  Ground water is the water which percolated in the ground
after rainfall. Therefore, the quality of ground directly
depends on rainfall. As the rainfall is not uniformly spread
though out the year, the quality of ground water varies
throughout the year. In rainy season yield will be
maximum and in summer yield will be minimum.
 Water will also depend on the underground storage and the
geological formation of pervious and impervious. The
yield will also depend on the type of source of water. The
yield from the spring will also on the type of source of
water. The yield from the springs will be the depth of water
bearing stratum and its catchment area but it is usually less
and temporary which decreases in dry weather.
Suitability of ground water

6. The quantity of the water drawn from deep
wells and tube-wells is much more, because
water is tapped from several aquifers into
these wells. Therefore, supplies of tube
wells and deep are constant and more
reliable than shallow well and springs. If we
compare the quality of ground water with
surface water, we will see that more quality
is available from surface sources.

7. The quality of ground water is much better than surface
water, because surface water contains large amount of
suspended impurities, whereas ground water is free from it.
But, sometimes, ground water contains dissolved minerals ,
salts , etc. which come in its contact while it percolates down.
Some ground water contains high iron content. It is harder than
the surface water.
The strainer action of soil also removes large quality of
bacteria. Therefore, ground water is mostly free from bacteria.
Overall the ground water is good in quality, but require some
treatment to remove dissolved impurities and to improve its
chemical characteristics. If hardness is excessive, softening
using lime, lime soda process or zeolite process is necessary.
With regard to quality

8. SECECTION OF SOURCE OF WATER
SUPPLY
• The following points should be considered
while selecting the site for the source of water
for a water supply scheme.
• Location
• Elevation of intake point
• Quantity of available water
• Quantity of available water
• Topography of the intervention area

9. • Location :
The source of water must be situated as near as
possible to the town or city to minimize the cost of
conveyance.
•
• Elevation of intake point :
• The reduced level (R.L) of the intake point should be higher
than that of the city oe town to be supplied with, so as to
make the gravity flow possible.
• When the water is available at lower levels than the average
city level, pumping has to be resorted, which involves huge
operation cost and frequent possible breakdowns.
•
• Quantity of available water
• The quantity water available at the source must be sufficient
to meet the various water demands during the entire design
period of the scheme

10. • Quality of available water:
• The water available at the source must not be toxic, poisonous
or in any other way injurious to health. The impurities present
in the water should be as less as possible, and should be such
as to be removed easily and economically by normal treatment
method.
• Bad quality water requires excessive treatment and increases
the cost.
• Topography of the intervening area:
• The area or land between the source and the city should not
be3 highly uneven. In other words, it should not contain deep
valleys or high mountains and ridges. In such uneven
topography the cost of trestles for carrying water pipes in
valleys and that of constructing tunnels in mountains, shall be
enormous.
• Cost
• While selecting a source of water for a water supply scheme,
it is necessary to estimate the cost of the project.
• The cost of the project depends on
•

11. • SYSTEM OF SUPPLY: if water is to be gravity
method the cost will be low, but in case of pumping
the cost will be higher.
• DIFFERENCE IN LEVEL OF SOURCE
AND THE CITY: if the source of water is at
higher elevation as compared to the city, water can be
supplied by gravity and cost will be less. If the source
of water is at lower elevation as compared to the city
,water has to be supplied by pumping. in this case the
cost of pumping an operating will be high

12. • Distance of city from the source of water: if
the distance of the city from the source of water is
large, the cost of pipeline , valves fittings, etc. will
increase.
• Topography: in a plain topography the cost of
construction of the water supply scheme will be less
.but in case of uneven topography this cost will be
higher.
• Availability of construction material: if
suitable construction materials are available in the
nearby area, the cost of construction of the water
supplies scheme isreduced.

13. Criteria considered for water supply scheme:
The water supply schemes are prepared by the combination of
field observations and office work.
The following points should be considered while planning a
water supply scheme:
Financial aspect.
Population
Quality of water.
Rate of consumption.
Source of water supply.
Sanitary survey of area.
Topography of area.
Trends of town development.

14. •Financial aspect.
In the initial stage the water supply scheme the data regarding
the available of fund for the scheme be obtained. The scheme
should than be planned in relation to the fund available.
Attempt should be made to make the scheme as scheme as
economical as possible.
•Population
Water supply projects are designed to serve over a specified
period of time after completion of the project. This time period
is called design period. Water work are generally designed for
30 years.
So, the problem population of the town or city should be
ascertained for the future decades by suitable method.

15. •Quality of water
The quality of available water decides the line of
treatment of water. The impurities present in water should
be as less as possible, and should be such as to be
removing easily and economically by normal treatment
methods.
Bad quality water requires excusive treatment and
increases the cost.
Rate of consumption.
The demand of water depend on various uses such as
domestic, public, industrial, etc.
The rate of consumption of water per capita should be
decided by carefully considering all the these possible
uses. This rate when multiplied by the population, gives
the total quantity of water required for the water supply
scheme.

16. Sources of water supply
The cost of the water supply scheme depends on the
selection of the site for the source of water. So, the source
of water should be such that the cost of conveyance and
water treatment may be reasonable.
Sanitary survey of area:
The sanitary survey of area surrounding the available water
source helps in estimating the possible pollution or
contamination of water from such source. The sanitary
survey includes the collection of information regarding
possible sources of water pollution.
Topography of area:
The topography map of the area to be served by the scheme
should be prepared and it should be studies in relation to the
low lying area, ridges, density of population etc. the
topographic study help in deciding and economic water
supply scheme.

17. •Trends of town development:
The trends of town development in future should be
predicated and properly adjusted in the water supply scheme.
Such trends may take various forms like possibility of new
industries, public institutions, recreation centers, residential
blocks, etc.

18. Thank you