WATER SUPPLY PROJECT 2076 Batch

DEPARTMENT OF CIVIL ENGINEERING

KHWOPA ENGINEERING COLLEGE
(AFFILIATED TO PURBANCHAL UNIVERSITY)
LIBALI – 2, BHAKTAPUR, NEPAL
A
PROJECT REPORT
ON
SIPADOL PLANNING WATER SUPPLY PROJECT

(Course Code: BEG 485 CI)

SUBMITTED BY
Abhidha Acharya (760201)
Anish Sainju (760203)
Anjan Gosai (760206)
Arjun Karki (760208)
In partial fulfillment for the award of the degree
OF

BACHELOR’S DEGREE IN CIVIL ENGINEERING

UNDER THE GUIDANCE OF
Er. RAZIM GANESH

MARCH 2024
WATER SUPPLY PROJECT 2076 Batch

ABSTRACT
The final year project report intended concisely summarized the outcome of the project
and is the final document in the Sipadol drinking water supply project. The project report
is used to document success, lessons, learned, in order to improve the project, deliver for
the future. The main objective of the report is to analyze the different aspects of the
Sipadol drinking water supply project.
The project area lies in Suryabinayak Municipality, Bhaktapur Nepal. It lies in the
Southern part of Araniko Highway. The source of our project is ground water. The source
of water as per water quality test was compared to NDWQS (2079) is clear and safe for
drinking, with simple treatment for chloride. For this project, we have design population
of 1,345. For this project, we have used HDPE pipes of various diameters. We have used
overhead reservoir tank of 40m3. Water supply project is intermittent for pumping as well
as distribution. The length of transmission line is 520.330m and 90mm in diameter. It
connects the pipelines from source to our reservoir. The length of distribution line is
3559.806m and diameter varies from 20mm to 75mm.
With the help of the final year project work, we came to learn about teamwork, co-
ordination and working together to achieve a common goal.
WATER SUPPLY PROJECT 2076 Batch

ACKNOWLEDGEMENT
First of all, we must acknowledge our deep sense of gratitude to the Department of Civil
Engineering, Khwopa Engineering College for providing us the project and for the
encouragement for us to enroll the project.
We are very thankful to our supervisor Er. Razim Ganesh giving theoretical and practical
knowledge and also for guiding us during the project duration.
We would also like to express deepest gratitude to Er. Sujan Maka (Principal, Khwopa
Engineering College) and Er. Amit Shankar Ranjit (HOD, Department of Civil
Engineering) for their administrative and academic help.

Abhidha Acharya (760201)

Anish Sainju (760203)
Anjan Gosai (760206)
Arjun Karki (760208)
WATER SUPPLY PROJECT 2076 Batch

Table of Contents
INTRODUCTION TO THE PROJECT
LIST OF ABBREVIATION
SALIENT FEATURES
1. INTRODUCTION
1.1 Background
1.2 Objective
1.3 Literature review

2. COMPONENTS OF PROJECT
2.1 Source of The Project
2.2 Technical Aspect
2.2.1 Existing Water Supply Project
2.2.2 Proposed Project
2.2.3 Coverage Population

3. DESCRIPTION OF PROJECT WORK

1.1 Location and Accessibility
1.2 Topography
1.3 Climate
1.4 Occupation and Socio-Economic Structure
1.5 Projected Population and House
1.6 System Design
1.7 Cost Estimate

2. METHODOLOGY
2.1 Selection of Source
2.2 Detailed Survey
2.3 Estimation of water demand
2.3.1 Domestic Demand
2.3.2 Institutional Demand
2.3.3 Public Tap
2.4 System of supply
2.4.1 Continuous Supply
2.4.2 Closed Supply
2.4.3 Gravity Supply
2.5 Reservoir Sizing
2.5.1 Storage Capacity of balancing reservoir
2.5.2 Supply
2.5.3 Demand
2.5.4 Surplus
2.5.5 Deficit
2.5.6 Volume of RVT
2.6 Hydraulic Design
WATER SUPPLY PROJECT 2076 Batch

3. TECHNICAL DEFINITION
3.1 Gravity Water Supply system
3.1.1 Open System
3.1.2 Closed System
3.1.3 Intermittent System
3.1.4 Continuous System
3.2 Intake
3.3 Overhead tank
3.4 Distribution Chamber
3.5 Collection Chamber
3.6 Storage Tank
3.7 Pipelines
3.8 Transmission main
3.9 Distribution main
3.10 Water Supply distribution system
3.11 Pipe networks
3.12 Layout of distribution work
3.12.1 Grid Iron System
3.12.2 Ring System
3.12.3 Radial System
3.12.4 Dead End System
3.13 Hydraulic Design of pipes
3.13.1 Flow Velocity
3.13.2 Static head
3.13.3 Residual head
3.13.4 HGL
3.14 Pipe losses
3.14.1 Losses in pipe
3.14.2 Friction losses in pipe
3.14.3 Calculating Head loss for a known pipe
3.14.4 Calculating flow for known head
3.14.5 Minor losses
3.15 Pipes
3.15.1 Cast Iron Pipes
3.15.2 Wrought Iron pipes
3.15.3 Steel pipes
3.15.4 Galvanized Iron Pipe
3.15.5 Concrete Pipe
3.15.6 Plastic Pipe
3.16 Valve
3.16.1 Sluice Valve
3.16.2 Reflux/Check Valve
3.16.3 Safety valves/ automatic cutoff valve
3.16.4 Air relief valve
3.16.5 Butterfly valve
3.16.6 Drained Valve
WATER SUPPLY PROJECT 2076 Batch

6.0 DESIGN CRITERIA

6.1 Population
6.2 Annual Population Growth Rate
6.3 Design Period
6.4 Population Forecast
6.4.1 Geometrical Growth Method
6.5 Water Demand
6.5.1 Domestic Demand
6.5.2 Institutional demand
6.5.3 Commercial Demand
6.5.4 Industrial Demand
6.5.5 Wastage and Leakage
6.5.6 Fire Demand
6.6 Water Consumption Pattern
6.7 Determination of storage size
6.8 Pipeline Design
6.8.1 System Flow rate
6.8.2 Basis of Design
6.9 Pipeline Survey
6.10 Flow Velocity
6.11 Minimum Velocity
6.12 Maximum Velocity
7.0 Overhead Tank Design
7.1 Tank
7.2 Types of water tank
7.3 Elevated Tank
7.3.1 Intze tank
8. Water Sample Test
9. Reservoir Sizing
10. Estimation and Costing
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11. Drawings
WATER SUPPLY PROJECT 2076 Batch

INTRODUCTION TO FINAL YEAR PROJECT

The practical implementation of the theoretical knowledge helps to build up confidence
and to widen up one’s vision to the various aspects of fieldwork. With this view point, the
Purbanchal University has included this Civil Engineering Project in the second part of
final year of Bachelor’s Degree in Engineering.
Nepal is a developing country and safe drinking water is still not available to a large
population of our country. Drinking water is one of the basic requirements of human,
improvement in water supply and sanitation helps largely in the delivery of sustainable
health and hygienic services. Realizing the necessity and scope of the rural water supply
projects, we the project group decided to do the final year project on “Sipadol Planning
Water Supply Project” with the help of guidance of our respected teacher, Er. Razim
Ganesh. As a result, we prepared this report of “Sipadol Drinking Water Supply Project”.

The students involved are: -

Abhidha Acharya (760201)
Anish Sainju (760203)
Anjan Gosai (760206)
Arjun Karki (760208)
WATER SUPPLY PROJECT 2076 Batch

SALIENT FEATURES
1. Name of Scheme: Sipadol Drinking Water Supply Project
2. Location: Sipadol
3. District: Bhaktapur
4. Municipality: Surya Binayak
5. Geographical features: Hilly Region
6. Terrain: Mild Slope
7. Climate: Moderate
8. Geology: Alluvial sandy soil
9. Type of water supply system: Gravity flow system
10. System of supply: Intermittent System
11. Type of source: Deep Boring
12. Depth of deep bore: 220m
13. Measured yield: 12 Lps
14. Pumping time: 7 hrs.
15. Distribution time: 5 hrs.
16. RVT: Overhead (1)
17. RVT size: 40 m3
18. Length of transmission line: 520.330m
19. Length of distribution line: 3559.806m
20. Tap stand: 1
21. No. of household served: 280
22. Present population: 1670
23. Design population: 1345
24. Population growth rate: 0.92% (census 2021)
25. Design period :20 yrs.
26. Total estimated cost:

27.
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LIST OF ABBREVIATIONS
BCR : Benefit cost ratio
BPT : Break pressure tank
CC : Collection chamber
DFID : Department for international development
DC : Distribution chamber
DDC : District development committee
DWSP : Drinking water supply project
GI : Galvanized iron
HDPE : High density polyethylene pipe
HH : Household
HGL : Hydraulic grade line
IC : Interruption chamber
Lpcd : Liter per capita per day
Lpd : Liter per day
Lps : Liter per second
NGO : Non-government organization
O&M : Operation and maintenance
RCC : Reinforced concrete cement
RT : Reservoir tank
WSP : Water supply project
WATER SUPPLY PROJECT 2076 Batch

1. INTRODUCTION

1.1 Background
Water is a fundamental necessity for life, crucial for the survival and well-being of any
community. Access to clean and sufficient water is a basic human right in today's world.
It is the government's duty to ensure that all citizens have access to safe drinking water
that is easily obtainable, consistently available, and of high quality. In rural regions, water
supply systems are often managed by local communities, who actively participate in their
implementation. In contrast, urban areas rely on more advanced and carefully planned
water supply infrastructures, which are integral to maintaining a standard of living in
cities and towns.
Sipadol Planning is a low income housing planning situated at Suryabinayak
Municipality, east to Araniko Highway. Proposing planned distribution of water supply in
this region is more than a need, a corner stone for standard life of town dwellers.
1.2 Objectives
 To be familiar with engineering aspects of the real project.
 To get familiar with the community-based project.
 To gain knowledge on the economic analysis of water supply project.
 To design an urban water supply project by applying theoretical knowledge
we gain.
 To get familiar with different components of urban water supply system.
 To get familiar with the engineering aspects of the real project.
 To gain knowledge on quantity estimation of water supply project.
 To execute the acquired knowledge and skill of water system into a
practical approach.
 To examine the sufficiency of water source to meet the demand and impact
of Sipadol Planning WSP due to increase demand.

1.3 Literature review

As for our Final year project, we choose urban water supply system as our subject and
proceed to make a report on the title “Sipadol Planning Water supply Project”. This
project deals with the study of Sipadol planning and its present to future water
demand, source of water supply, design of water supply distribution.

The project area is located at Suryabinayak municipality, Bhaktapur. To accommodate

the growing population by providing planned and well managed settlement area and
to prevent unmanaged urbanization Sipadol planning has been initiated. We made a
design that can provide adequate drinking water to the Population that current reside
here and for the future growing population.

For this project, we had gone through several previous reports, books, peoples and
help from our respected supervisor. Literature review was done from the starting to
the end of this project and the project would not have been completed on time without
the help of it. We visited some water supply projects that were currently running in
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WATER SUPPLY PROJECT 2076 Batch

the nearby projected area. The project area also had a current water supply system that
was being designed due to which it was made easier for us to obtain log data about the
borehole. We carried out some reports of our seniors on the similar topic which helped
us for hydraulic design of the pipeline. We also studied guidelines for “Urban Water
Supply and Sanitation (Sector) Project” (UWSSP).

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2. COMPONENTS OF PROJECT
2.1 Source of the project
The source of project is borehole which lies at the distance of 520.330m from
the distributed area. Discharge from the borehole is 12 lps.

2.2 Technical aspect

2.2.1 Existing Water Supply Project
There are an existing water supply project and people use water from
borehole but the borehole is not enough to fulfil the water demand. With the
increase in land use as settlement and increasing household, another borehole
was created to fulfil the water demand. The project aims to fulfill the water
demand of that area. Area is located in Taudole, Suryabinayak-08.

2.2.2 Proposed Project

It is an intermittent gravity water supply project. The source of the
project is groundwater(borehole) having discharge of 12 lps. As per
water demand of the project area, it incorporates 1 RCC tank
having volume 40 m3. The water demand is calculated with the per
capita domestic water demand of 120 Lpcd with population growth
of 1%.

2.2.3 Coverage Population

The proposed project is designed for supplying drinking water for
the people of Taudole, Suryabinayak 08. The design population is
1,346.
The construction period is 1 year with the design period of 20 years

3.0 DESCRIPTION OF THE PROJECT AREA

3.1 Location and Accessibility
The project is situated at Bhaktapur District, Suryabinayak Municipality. It lies in
hilly region. The altitude of the project area varies from 1250 m to 1180 m above
mean sea level(27°38'51.70"N,85°26'36.40"E). The altitude of the borehole is at
1273.825 m and main reservoir is 1243 m in elevation.

3.2 Topography
The purposed source for the gravity water supply project is located in hilly region.
The source is located near the jungle and the soil type of the area is sandy alluvial
soil.

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3.3 Climate
The project lies in the Kathmandu valley i.e.in the hilly belt of Nepal, it has
moderate temperature. The average daily temperature of area in summer is 27°C
and that in winter is 18°C
3.4 Occupation and Socio-economic Structure
People having various occupation resides in the projected area. The major ethnic
group in the area is Brahmin, Chhetri, Newar etc. Social group collectively
participates in different social works including marriages, worships etc. which
indicates that the beneficiary communities are capable of working in group.
3.5 Projected Population and household
The present population including school student has been obtained from the
survey work by counts and sample method. The domestic water demand is 120
liters per capita per day. Population growth rate of the project is 1% and the year
2024 has been taken as survey year and 2024 has been taken as base year from
which 20-year design period and population has been forecasted in accordance
with geometrical progression method.

P = Po * (1+ r)n

Where, P0 is the present population.

r is the mean geometric growth rate per annum.
n is the number of years.
The design population of the service area is 1895.
3.6 System Design
The size and type of transmission and distribution pipe mains are computed on the
basis of survey data. The water supply system has been designed based on
criterion (design period, population growth rate, type of the system, pressure
requirements etc.) of the standard DWSS design guidelines, unless specific site
condition does not demand otherwise. Pumping is to be done methods for
supplying water project which was designed as per the discharge, pressure, and
total dynamic head.
3.7 Cost Estimate
The detailed quantity cost estimate for various structure and pipe fittings have
been adopted from DWSS standardization guidelines. The updated cost estimation
is based on approved district rate of Bhaktapur for fiscal year 2080/081 by which
the unit rates have been derived.

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4.0 METHODOLOGY
We visited the project site for both source and planning area for performing
preliminary survey where we did map study of the site via google earth. The
reconnaissance survey was carried out where the index sketch of the topography
was drawn. We also gathered some information about the previous water supply
project that existed in that area with the locals and other personals. After that the
civil engineering survey was carried out for the determination of RL for the pipe
alignment and for the proposed structure through total station. The selection of the
structures, their numbers, sizing of balancing reservoir tank etc. were done as per
the numerical assessment following the necessary guidelines of DWSS.

4.1 Selection of the source

The proposed source of water for Sipadol DWSP is 225m deep boring to meet
the demand of required water without compromising to meet the water demand of
former service areas.

4.2 Detailed Survey

The ground level survey was done with the help of total station along with its
accessories such as prism and compass. Before that, reconnaissance survey was
done.

4.3 Estimation of water demand

The service area of Sipadol DWSP is planned settlement zone, so the main
water demand is of domestic demand. The area accommodates one school, one
office and one public tap.

4.3.1 Domestic Demand

Total population: 1120
Growth rate: 0.92%
Design Population: 1346
Demand: 161415 Lpd
Losses: 10 %
Peak Factor: 1.5
Total Demand: 266334.882 Lpd

4.3.2 Institutional Demand

No. of Schools: 1 no
Students: 500
No. of Office: 1
Staff: 50
Losses: 10%
Total Demand: 8800 Lpd

4.3.3 Public Tap

No. of public tap: 1
Total demand: 8640 Lpd

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4.4 System of Supply

4.4.1 Intermittent System
In intermittent system, water is pumped or distributed for certain period of
time. This system is adopted when the discharge at the source is not sufficient
enough to meet the designed demand. The water is distributed only for some hours
a day so as to meet the water demand. In the rest of the hours of the day, water
supply is shut off at the reservoir tank to allow it to be refilled.

4.4.2 Gravity Supply

In gravity system, water is conveyed through pipes by gravity only. This
system is adopted where the treated water to be supplied is available at a higher
level than that of distribution areas.

4.5 Reservoir Sizing

4.5.1 Balancing Reservoir
The size of the Reservoir has been calculated so that it can provide a
balancing storage to meet the hourly variation of the day. The quantity
of water required to be stored in the reservoir for balancing the variable
demand of water against the constant rate of inflow is call balancing
reservoir
The capacity of a balancing reservoir is determined on the basis of inflow
to the reservoir and demand of the consumers. The water inflow to the
reservoir is set for a total of 7 hours per day and water outflow the
consumers is set for 5 hours per day.

4.5.2 Supply
The quantity of water entering the RVT from source in a given time period is
Supply.

4.5.3 Demand
The demand for water supply refers to the total amount of water needed or
desired by individuals, businesses, and other entities within a specific area
over a given period. This demand can be influenced by various factors,
including population growth, economic activities etc.

4.5.4 Surplus
The surplus of water supply refers to the amount of excess water pumped from
the source to the reservoir tank.
4.5.5 Deficit
The deficit of water supply refers to the insufficient amount of water in the
reservoir tank to provide to the general public.
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WATER SUPPLY PROJECT 2076 Batch

4.5.6 Volume of RVT

The Volume of RVT shows the size of the reservoir tank.

4.6 Hydraulic Design

The pipe was selected with national standard sizes such that the total head loss was
maintained to the limit.
Velocity was simply calculated using Hasen Williams Formula as:
HL/L = (10.659*Q1.85)/(C1.85*d4.86)
Where, HL = Head Loss, m
L = Length of Pipe, m
Q = discharge, m3/s
C = Hazen Williams coefficient
d = diameter of pipe, m

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5.0 TECHNICAL DEFINITION

5.1 Gravity water supply system:
A scheme where water source is located at an elevation higher than service area is
referred to as gravity scheme water can be supplied by gravity from the source to the
storage tank and distribution again by gravity. Location of the storage at a higher altitude
allow adequate head to be maintained a gravity scheme is a reliable water supply system.
Gravity flow water system can be classified as:
1. Open system
2. Closed system
3. Intermittent system
4. Continuous system
5.1.1 Open system
This system is used where the safe yield of source meets the peak water demand of the
service area. This system does not require installation of any control devices. And all its
pipe is distribution line. Static pressure therefore never builds up in the system. Brake
pressure chamber is generally not required. In such system the concept is that the taps can
be left open and flowing continuously all day and still provide continuous and steady
flow. However, this can lead to environment hazard if waste water is not adequately
drained off.
Such system may not be justified when the distanced between the water source and the
service area is large since pipe cost become high and hence increase the project cost.
5.1.2 Closed system
This system is used when the safe yield of the source cannot meet the peak water demand.
A reservoir tank is necessary to store water for the peak demand period. All tap-stand
have faucets and valves to control the flow from being wasted. A closed system,
therefore, is subjected to the maximum static water pressure and should be designed
accordingly.
5.1.3 Intermittent system
This system is adopted when the discharge at the source is not sufficient enough to meet
the designed demand. The water is distributed only for some hours a day so as to meet the
water demand. In the rest of the hours of the day, water supply is shut off at the reservoir
tank to allow it to be refilled. The intermitted system is the least desirable type to build
because the likelihood of contaminated is higher, increase the chance of wear and tear on
the control valves at the reservoir and requires manpower to operate them. Moreover,
when the material and/or water resource are limited, only intermittent supplies can be
provided.
5.1.4 Continuous system

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In the continuous system water is available in the distribution lines all the time. The
system is adopted when there is sufficient discharge at the source. Water in the continuous
system is available whenever the faucet is opened. Since the water is continuous
available, it is more desirable, because service is available all the time. The distribution
line is always under pressure so the possibility of contamination by negative suction in
the pipeline does not exist.
Merits of continuous flow system over storage system include:
a) Supply of water does not run out
b) No requirement to store water
Demerits of continuous flow system:
a) Waste of water by irresponsible users
b) Difficulties in operation maintenance
5.2 Intake
An intake is a structure which continuous abstract the design flow from the source. It is
the first point in a water supply system and is them funneled into the pipe line i.e.
transmission main. The fundamental purpose if the intake works is to collect water from
one or several points and focus this flow at a single point the entrance to the pipeline. The
efficiency and functioning of the water supply scheme largely relies upon the nature,
location and construction of intake, hence requires a great care. Intake are the structures
which comprises of the opening, grating or strainer through which the crude water from
source like river, canal or reservoir enters and is conveyed to transmission main. Water
from the sump well is pumped through the rising mains to the treatment plants.
The intake is sit specific in designs. Several alternate designs are possible for the intake.
Further, special care should be taken while selecting the site for intake construction. Few
measures are: -
 The intake should be built on the stable soil (i.e. resistance to erosion and
landslide)
 Intake should be built at such site with no possibility of contamination of the
source.
 Intake should be easily accessible for regular inspection, cleaning, operation and
maintenance.
 Intake should be built at the section of maximum water from the discharge.
 Intake should be built site specifically.

5.3 Overhead tank

An overhead water tank is a container for storing water above the surface. Overhead
water tanks are used to provide storage of use in many applications, drinking water,
irrigation agriculture, fir suppression, agricultural farming, both for plants and livestock,
chemical manufacturing, food preparation as well as many other uses. Overhead water

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tanks are used for domestic water storage and commercial water storage purposes. They
are generally placed over the rooftop of any house, building or apartment. These tanks
circulate the water through its distributary channels or pipes to the taps.
5.4 Distribution chambers
Distribution chamber is provided to divide the flow. From the hydraulic point of view, it
provides an environment to distribute water with reasonable accuracy. Generally, these
chambers work satisfactory up to a flow of 2 to 3 lps. By use of DC, designed separate
average flows could be supplied to multiple branches heading towards decentralized
reservoirs. For more accurate distribution of flow, mouth piece and gate valves are used at
outlet of DC. DC saves the cost of pipe between the RVT and DC.
5.5 Collection chamber
The process of collection chamber areas to collect water from more than one water
sources, settle course materials and remove floating matter like leaves as well. Also in
case, if the intake could not be constructed at the safe place, collection downward system
components. Construction of CC with provision of minimum of 5m static head can avoid
backward if multiple sources are tapped. The outlet capacity (i.e. drainage capacity) of
CC must be equal to or greater than the maximum flow capacity of the pipe line between
intake and CC to avoid overflow from it. It should have provision for inlet, outlet, over-
flow and washout mechanics.
5.6 Storage tank
Storage tank is constructed to balance the variation of water demand in a day. Reservoirs
can be created by controlling a stream that drains an existing body of water. Thay can also
be constructed in river valleys using a dam. Alternately, a reservoir can be built by
excavating flat ground or constructing retaining wall. The reservoir tank serves to store
water that is provided by source during low demand periods, for use during high demand
period. In gravity flow water supply schemes, the reservoirs are usually constructed either
of stone masonry or RCC.
Reservoirs are provided to absorb hourly fluctuation in water demand. Reservoir is
necessary in system when,
 Pipeline without reservoir cannot fulfil the peak demand of the tap.
 Daily water demand is greater than safe yield of source during daylight hours.
 Pipeline distance from the source to community is so far that it is more
economical to use smaller pipe size and built a reservoir tank.
5.7 Pipelines
The pipelines transfers water from the source to the service area. Pipe requires high
investment outlay and hence careful consideration is necessary for its design, the
alignment selection, size and material require almost caution. Proper selection of pipe
alignment route is essential to ensure that the pipeline is laid through stable terrain to
minimize disruption later and to ease the operation and maintenance works. After the
pipeline is laid, the protection work needs to be carried out against backfill material
getting wash away.

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Pipelines in water supply scheme consist of: -

 Transmission main
 Distribution main
5.8 Transmission main
Transmission mains are larger pipes which are designed to move large quantities of water
from the source of supply, such as a treatment plant or groundwater well, and provides
water to the smaller distribution mains. A large water pipe which is used to extend and
convey water between a water system’s supply/storage facilities and distribution mains.
The definition of a water transmission main depends upon the function of the pipelines
concerned within the system concerned. A large water pipe which is used to extend and
convey water between water system’s supply/storage facilities and distribution mains. The
definition of a water transmission main depends upon the function of the pipelines
concerned within the system concerned. A large water pipe which is used to extend and
convey water between a water’s supply/storage facilities and distribution mains. The
definition of a water transmission main depends upon the function of the pipeline
concerned within the system concerned.
5.9 Distribution main
In water distribution networks, a distribution main is the source for all end users that have
drinkable or fresh water delivered to their home or commercial property via the water
system provided by the community’s water system. The distribution main is the largest
running pipe in the entirety of the water system, usually considered the output source of
all the different methods many communities use to hold their surplus treated water in
holding tanks or water towers. The reason these pipes are referred to as distribution mains
is because of their main function, which is to distribute the water that is treated through
the system to the users in the community.
Civic plumbing application have changed greatly over time, and the use of distribution
system that are both adaptive and interchangeable has become necessary as an efficient
means of delivering potable water to everyone in the community. The use of a distribution
mains allows for the interchangeability of pipes within a community’s system in the case
of pipe breakage or when a new piping system needs to be integrated into the existing
one. This makes the tasks of repairing and expanding the system much more easily
accomplished. Expandability is also a key factor and distribution main planning, as these
pipes and the layout the distribution main is used is determine how easily the mains can
be tapped into deliver water to new areas within a community. With the rate many
communities are growing, the ability to expand is key in determining how the distribution
mains are laid out in areas that require new water services. As a results, many of the pipes
that are used as distribution mains are pre-fitted with junction openings that allow for the
easy application of smaller capillaries at later times.
5.10 Water supply distribution system
The purpose of distribution system is to deliver water to consumer with appropriate
quality, quantity and pressure. Distribution system is used to describe collectively the
facilities used to supply water from its source to the point of usage. A pipe network for

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WATER SUPPLY PROJECT 2076 Batch

distribution of water to the consumers (which may be private houses or industrial,

commercial or institution establishments) and other usage. A pipe network for distribution
of water to the consumer (which may be private houses or industrial, commercial or
institution establishments) and other usage points (such as fire hydrants). Water supply is
the provision of by public utilities commercial organizations, community endeavors or by
individual, usually via a system of pumps and pipes. Irrigation is covered separately.
Requirements of good distribution system
 It should be capable of supplying water at all the intended places with sufficient
pressure head.
 It should be capable of supplying the requisite amount of water during
firefighting.
 The layout should be such that no consumer would be without water supply,
during the repair of any section of the system.
 All the distribution pipes should be preferably laid one meter away or above the
sewer lines.
 It should be fairly water-tight ass to keep losses due to leakage to the minimum.
 Water quality should not get deteriorated in the distribution pipes.
5.11 Pipe networks
In fluid dynamics, pipe networks analysis is the analysis of the fluid flow through a
hydraulics networks, containing several or many interconnected branches. The aim is to
determine the flow rates and pressure drops in the individual sections of the network. This
is a common problem in hydraulic design.
To direct water to many users, municipal water supplies often route it through a water
supply network. A major part of this network will consist of interconnected pipes. This
network creates a special class of problems in hydraulic design, with solution methods
typically referred to as pipe network analysis. Water utilities generally make use of
specialize software to automatically solve these problems. However, many such problems
can also be addressed with simpler methods, like a spreadsheet equipped with a solver or
a modern graphing calculator.
5.12 Layouts of distribution network
The distribution pipes are generally laid below the road pavements, and as such their
layout generally follow the layouts of roads. There are, in general, four different types of
pipe network; any one of which either singly or in combinations, can be for a particular
place. They are: Grid, Ring, Radial and Dead-End System.
5.12.1 Grid iron system
It is suitable for cities with rectangular layout, where the water mains and branches are
laid in rectangles.
Advantages:
1. Water is kept in good circulation due to the absence of dead ends.

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WATER SUPPLY PROJECT 2076 Batch

2. In the cases of a breakdown in some section, water is available from some all
branches.
Disadvantages:
1. Extract calculation of sizes of pipes is not possible due to provision of valves on
all branches.
5.12.2 Ring system
The supply main is laid all along the peripheral roads and sub mains branches out from
the mains. Thus, this system also follows the grid iron system with the flow pattern
similar in character to that of dead-end system. So, determination of the sizes of pipes is
easy.
Advantages:
1. Water can be supplied to any point from at least two directions.
5.12.3 Radial system
The area is divided into different zones. The water is pumped into the distribution
reservoir kept in the middle of each zone and the supply pipes are laid radially ending
towards the periphery.
Advantages:
1. It gives service.
2. Calculation of pipe sizes is easy.
5.12.4 Dead end system
It is suitable for old towns and cities having no definite pattern of roads.
Advantages:
1. Relatively cheap.
2. Determination of discharges and pressure easier due to a smaller number of
valves.
Disadvantages:
1. Due to many dead ends, stagnation of water occurs in pipes.

5.13 HYDRAULIC DESIGN OF PIPES

5.13.1 Flow velocity:
While sizing the pipe diameter, minimum and maximum flow velocities in the selected
pipe should also be considered. Minimum velocity in the pipeline should be fixed to wash
sediment particles which should not be allowed to settle at nay point. The velocity must
be sufficient to move sediment along with water.

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WATER SUPPLY PROJECT 2076 Batch

To destroy excess head, small sizes pipes are used, which however, increases the flow
velocity. At velocities greater than 3m/s air and water tend to mix affecting the flow and
head loss. Also, at high velocities when the faucets are suddenly closed the phenomenon
of water hammer may also occur.
Hence, the following minimum and maximum velocity limits should be adopted.
5.13.2 Static head:
It is the maximum height reached by pipe after the pump (also known as the ‘discharge
head’). Static lift is the height the water will rise before arriving at the pump (also known
as the ‘suction head’). Friction loss (or head loss).
5.13.3 Residual head
The dynamic head remaining at the end of a pipe section is referred as residual head. The
minimum residual head to be maintained is 5m. Residual head in public stand post is
desired to be 15m and the absolute maximum residual head is 56m.
5.13.4 Hydraulic grade line (HGL)
If a pipe is under pressure, the hydraulic grade line is that level water would rise to in a
small, vertical tube connected to the pipe. Hydraulic gradient is a line joining the points
of highest elevation of water in a series of vertical open pipes rising from a pipeline in
which water flows under pressure. It represents the energy line which is sum of pressure
head and datum head of water at a particular point.
5.14 Pipe losses (major/minor)
5.14.1 Losses in pipes
The basic approach to all piping system is to write the Bernoulli equation two points,
connected by a streamline, where the condition are knows. For example, the surfaces of a
reservoir and a pipe outlet.
2 2
P0 V 0 P1 V 1
H0+ + + ∆ h p =H 1+ + +∆ h m
ρg 2 g ρg 2 g
The total head at point o must match with the total head at point 1, adjusted for any
increase in head due to pump, losses due to pipe friction and so-called “minor losses” due
to entries, exits, fitting, etc. pump head developed is generally a function of the flow
through the system, however this will be dealt with in another section of the course.
5.14.2 Friction losses in pipes
Friction losses are a complex function of the system geometry, the fluid properties and the
flow rate in the system. By observation, the head loss is roughly proportional to the
square of the flow rate in most engineering flows (fully developed, turbulent pipe flow).
The observation leads to the Darcy-Weisbach Equation for head loss due to friction:
2
fL V
∆ hf =
2 gD

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WATER SUPPLY PROJECT 2076 Batch

Which defines the friction factor, f. f is insensitive to moderate changes in the flow and is
constant for fully turbulent flow. Thus, it is often useful to estimate the relationship as the
head being directly proportion to the square of the flow rate to simplify calculation.
VD
f = f (Re, ε/d, pipe cross-section) ℜ=
γ
Reynolds number is the fundamental dimensionless group in viscous flow. Velocity
times length scale divided by kinematic viscosity.
Relative roughness relates the height of a typical roughness element to the scale of the
flow, represented by the pipe diameter, D
Pipe cross-section is important, as deviations from circular cross-section will cause
secondary flows that increase the pressure drop. Non-circular pipes and ducts are
generally treated by using the hydraulic diameter,
4 A 4∗cross−sectional area
D H= =
P wetted perimeter of pipe
In place of the diameter and treating the pipe as if it is round.
For laminar flow, the head loss is proportion to velocity rather than velocity squared, thus
the friction factor is inversely proportion to velocity.
64
Circular pipes: f = ℜ

k
Non-circular pipes: f = ℜ , 48≤ k ≤ 96

5.14.3 Calculating head loss for a known flow

From Q and piping determine Reynolds number, relation roughness and thus the friction
factor. Substitute into the Darcy-Weisbach equation to obtain head loss for the given flow.
Substitute into the Bernoulli equation to find the necessary elevation or pump head.
5.14.4 Calculating flow for a known head
Obtain the allowable head loss from the Bernoulli equation, then start by guessing a
friction factor. (0.02 is a good guess if you have nothing better.) Calculate the velocity
from the Darcy-Weisbach equation. From this velocity and the piping characteristics,
calculate Reynolds number, relation roughness and thus friction factor.
Repeat the calculation with the new friction factor until sufficient convergence is
obtained. Q=VA
Here’s a video discussing the three types of piping problems: …………….
5.14.5 Minor losses
Although they often account for a major portion of the head loss, especially in process
piping, thee addition losses due to entries and exits fittings and valves are traditionally
referred to as minor losses. These losses represent additional energy dissipation in flow,
usually caused by secondary flows induced by curvature or recirculation. The minor

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WATER SUPPLY PROJECT 2076 Batch

losses are any head loss present in addition to the head loss for the same length of straight
pipe.
Like pipe friction, these losses are roughly proportion to the square of the rate.
Defining k, the loss coefficient, by
2
V
∆ hm=Σ K
2g
Allows for easy integration of minor losses into Darcy-Weisbach equation. K is the sum
of all the loss coefficients in the length of pipe, each contributing to the overall head loss.
Although K appears to be a constant coefficient, it varies with different flow conditions.
Factors affecting the values of k include:
 The exact geometry of the component in question
 Flow Reynolds number
 Proximity to other fittings, etc. (tabulated values of k are for components in
isolation with long straight runs of pipe upstream and downstream.)
Some very basic information on k values for different fitting is included with these notes
and in most introductory fluid mechanics texts.
To calculate losses in piping systems with both pipe friction and minor losses use
2
L V
∆ hf =( f +Σ K )
D 2g
In place of the Darcy-Weisbach equation. The procedures are the same except that the k
values may also change or as iteration progresses.
5.15 PIPES
1. Pipes are circular conduits in which water flows under pressure.
2. Pipes should be designed to resists the internal water pressure and external
pressure due to soil and other imposed loads.
The various types of pipes based on pipe materials are;
5.15.1 Cast iron pipe
1. Made of cast iron.
2. Easy to join, can withstand high pressure, resistant to corrosion.
3. Long life (>100years), durable, strong and moderate in cost.
4. Brittle and very heavy, expensive and difficult to transport.
5. Suitable for distribution system.
5.15.2 Wrought iron pipe
1. Made up of wrought iron
2. Light in weight, easy in transport, handling, cutting, threading, working.
3. Costly corrosive and less durable than CI pipe.
4. Suitable for inside plumbing in buildings but not used due to high cost.

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WATER SUPPLY PROJECT 2076 Batch

5.15.3 Steel pipe

1. Made up of steel.
2. Life is 25 to 30 years, strong, light weight, can withstand high pressure (400m).
3. Costlier than CI pipes.
4. Liable to corrosion, can’t withstand external load when empty.
5. Occasionally used for main lines where pressure is high and diameter is more.
5.15.4 Galvanized iron pipe
1. Made up of WI or mild pipe which are galvanized by providing a protective
coating of zinc on inner and outer surface.
2. Cheap, light, easy in handling and transport 20 years of life.
3. May get corroded by acidic and alkaline water and liable to incrustation.
4. Used for main lines when pressure is high and pipe is exposed to open
atmosphere.
5.15.5 Concrete pipe
1. Made up of cement concrete.
2. It can be joined with bell and spigot joints.
3. Can withstand 150m head of water, resists corrosion and life is above 75 years.
4. Difficult to repair, liable to leak due to porosity.
5.15.6 Plastic pipe
1. Very commonly used pipes in Nepal due to its corrosion resistant nature, light
weight and economical.
2. Not used for transporting hot water.
The various types of plastic pipes are;
i) HDPE Pipe
1. Cheaper in cost.
2. Durable (life 50 years)
3. Light, corrosion resistant, easily joined.
4. Available in different diameter, to resist 4, 6, 10 kg/cm2.
ii) LDPE Pipe
1. Flexible pipe, require support closer due to flexibility.
2. Used in long rum, not suitable for installation of internal water supply.
iii) PVC Pipe
1. It is non corrosive, extremely light in weight.
2. Easy to handle and transport.
3. Strong and come in long lengths that lowers installation and transportation
cost.
4. They are prone to physical damage.

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WATER SUPPLY PROJECT 2076 Batch

5.16 Valve
The valves can be categorized into the following basic types:
5.16.1 Sluice valve
1. Commonly used valve to regulate the flow in the pipe.
2. Provided at every junction and at the interval of 3 to 5 km.
3. Cheaper and offer less head loss to flow than other valves of same purpose.
5.16.2 Reflux/Check valve
1. Maintains flow in one direction only in the pipe.
2. Normally placed after pump component.
5.16.3 Safety valve / Automatic cutoff valve
1. Use to release the unwanted pressure where the pressure where the pressure in the
pipe lines is maximum and pipes are reliable to burst.
2. Consists of a disc controlled by a spring which can be adjusted for any desired
pressure.
5.16.4 Air relief valve
1. Placed at the summit points in the pipe where air is accumulated which may block
the flow of water.
2. Releases the accumulated air.
5.16.5 Butterfly valve
1. Use for regulating the flow through pipe as in sluice valve but the head loss is
higher than in sluice valve.
2. Placed in the larger diameter because of low cost.
5.16.6 Drained valve
1. To empty or drain off the pipe for removing sand and silt deposited and for
inspection, repair etc.
2. Placed at the dead and at depression

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WATER SUPPLY PROJECT 2076 Batch

6. DESIGN CRITERIA
6.1 Population
The total population of a community to be served by the proposed water scheme needs to
be accurately surveyed. Firstly, the present population of the community needs to be
established. Once this is done population that is likely to be reached at the end of the
design period needs to be estimated.
The benefited population is defined as follows:
Present population: Population at the time of survey
Base year population: population when construction is completed and water scheme is
commissioned.
Design population: Population at the end of design period.
The population data should be taken on household basis by actual counting. Census
records are also needed to determine the average growth rate per annum.
The main aim of population survey is to determine:
 The population of residents in the residential houses/buildings.
 The population of day scholars and boarders in the academic institutions.
 The population of outdoor and indoor patients in hospitals and nursing homes.
 The population of birds and animals in the farms/houses.
 The populations of visitors (floating population) in the hotels and restaurants and
others, if any.
 The population survey is the basis for determining the capacity of the pipe
network.
 Knowing present population, we can forecast projected population to calculate the
projected water demand and capacity of the pipe network.
Present population
Population survey is one of the crucial activities in the design of a water scheme. The
surveyor/designer must spend sufficient time to establish the present population of the
community, in close co-operation with the members of the water users and sanitation
committee in particular and the beneficiaries in general. Population should be surveyed
according to the method explained in the procedural Guideline Vol. I.
6.2 Annual population growth rate
A water supply scheme should be designed to meet the community’s future water
requirements. The future population is estimated with the help of the past growth trend of
the particular community. Population growth rate critically affects the design because of
its impact on the projected population, and consequently on its cost.

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WATER SUPPLY PROJECT 2076 Batch

6.3 Design period

It refers to the duration for which a scheme will meet water demands of different water
users. This time begins from the day a scheme is commissioned and operated by the
users. The general practice in Nepal is to design water schemes for a period of 15 to 20
years.
The design period of a water supply scheme generally depends on:
 Rate of population growth,
 Present and future settlement pattern,
 Economical life of the system components, and
 Potential for development.
At high population growth rate, if a high design period is taken, the cost of the scheme
generally becomes high. As such there is less justification for the high investment by
taking a longer design period. When the growth rate is higher, phased implementation
may be considered or a lower design period may be more appropriate.
In some cases, storage tanks may be designed to meet the demand of a lesser period while
the distribution pipes are sized to meet the design water demand. Storage could be added
later. Logistic, re-mobilization of community and other administrative supports make
impractical to consider phased implementation in community water supply schemes.
It may be considered, only if obvious reasons such as very high population growth rate
justify it.
The time needed for construction of the scheme should also be taken into consideration
while computing the design population. Time needed for construction depends on the size
of the scheme, logistics, planning and participation of the users. Community water supply
schemes should be completed within a reasonably short period. Otherwise, the
participation of the community cannot be sustained satisfactorily. For design purposes 2
years construction period after the detailed design should be adopted.
6.4 Population forecast
The design population will have to be estimated with due regard to all the factors
governing the future growth and development of the project area in the industrial,
commercial, educational, social and administrative spheres. Special factors causing
sudden immigration or influx of population should also be foreseen to the extent possible.
Based on those factors there are numerous methods for population forecast, which are
listed as follows:
 Demographic method
 Arithmetic increase method
 Incremental increase method
 Geometrical increase method
 Decreasing rate of growth method
 Graphical method

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WATER SUPPLY PROJECT 2076 Batch

6.4.1 Geometric growth method

The population is forecasted by using the following formula:
Pn= P0*(1+r/100)n
where, Pn= population after n years
P0= present population
r = average percentage increase/
Geometrical mean
n= number of years

6.5 Water demand

The amount of water required for a rural community depends on the factors like economic
level of the community, their consciousness and other physical and social aspects.in case
of an urban, the demand would be higher due to commercial activities and transient
population.
Piped water supplies for the communities should be provided adequately for the following
purposes:
 Domestic demand
 Institutional demand
 Livestock demand
 Commercial demand
 Public demand
 Industrial demand
 Fire demand
 Wastage and leakage
6.5.1 Domestic demand
Water used by an individual for the different purpose is referred to as the domestic
demand and denoted as liter per capita demand (Lpcd). It includes drinking, cooking,
washing, bathing, toilets flushing, gardening, individual air conditioning etc.
For fully plumbed house: 120 Lpcd
For Partially plumbed house: 65 Lpcd
For rural areas: 45 Lpcd
6.5.2 Institutional demand
It includes the water required for various institutions such as schools, campus etc. the
institutional water demand shall be adopted as follows.
 10 liters/pupil/day for day-scholars
 65 liters/pupil/day for boarders

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WATER SUPPLY PROJECT 2076 Batch

6.5.3 Commercial demand

This includes the water demand of commercial establishments such as offices, hotels,
hospitals, restaurants, etc. The quality of water required for this purpose will vary
considerably with the nature and type of commercial establishments. The commercial
water demand shall be adopted as follows;
 10 liters/person/day for offices
 500 liters/bed/day for hospitals with bed
 2500 liters/day for hospitals without bed and health clinics
 200 liters/bed/day hotels with bed
 500 – 1000 liters/day for hotels without bed
 45 liters/seat/day for restaurants and tea stalls etc.
 10 liters/seat/day for auditoriums
6.5.4 Industrial demand
The presence of industries in or near the town has great impact on the water demand. The
quality of water required depends upon the type of industry. The survey shall be carried
out to determine the water demand of the existing industries and the provision foe
industrial demand shall be made accordingly.
6.5.5 Leakage and wastage
The water in this category is sometimes termed as unaccounted for water. This includes
the water lost due to leakage in mains, valves and other fittings, worn or damaged meters,
theft of water through unauthorized water connections and loss and waste of water due to
other miscellaneous reasons. The loss of water due to all these reasons should be taken
into account while estimating the total requirements of water. However, the quantity of
water lost and wasted due to all these reasons being uncertain it cannot be precisely
predicted.
The loss in the system as leakage and wastage shall be accounted as 10% of the total
demand.
The calculation shall be done using the following formulas:
Amount of water to be lost due to L and W = 0.10 x Total Water Demand
6.5.6 Fire demand
It is the quantity of water required for firefighting purpose. In thickly populated areas,
fires may break out and may result in severe damages if not controlled effectively. As
such for almost all the small and medium size towns, provision should be made in the
water supply system for meeting the demand of water for firefighting.
It is usual to provide for firefighting demand as a coincident draft on the distribution
system along with the normal supply to the consumers. It is related as a function of
population and may be computed from the following formulae:
Q=100 √ p

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WATER SUPPLY PROJECT 2076 Batch

Where, Q = quantity of water, in m3 per day

p = population, in thousands
The water required for firefighting shall not be more than one Lpcd.
6.6 Water Consumption Pattern

 Population
Present Population : Population at the time of survey
Base Year Population :Population when construction is completed and
Water supply scheme is
commissioned
Design Population :Population at the end of design period.
 Present Population
Since the water demand calculation is based on the population size, the designer
should spent sufficient time to establish the present population of the community.
 Annual Growth Rate
If the growth rate is below 1%, a growth rate of 1% is adopted, this will allow
some growth without substantially affecting the cost of the project. The past and
present annual population growth rate of Nepal can be seen as:
1.6922% in 2022 (Source: World Bank)
1.85% (2020 estimate) (Source: Nepal Population 2024 (Live))
1.92% (2021 estimate) (Source: Demographics of Nepal)
0.92% (2022 est.) (Source: Demographics of Nepal
 Design Period
The design period of a water supply scheme generally depends on:
1. Availability of water at source
2. Budget of project
3. Population Growth Rate
4. life of pipes and construction materials

If population growth rate is greater than 2%, design period is taken 15 years.
If population growth rate is less than 2%, design period is taken 20 years.

6.7 DETERMINATION OF STORAGE SIZE

The size of the reservoir for a particular community water system is a function of the
community's total demand, the community's consumption patterns, and the continuous
demand flow (CDF) from the source to the reservoir tank (R.T.). Among the above three
parameters the second one i.e. the consumption pattern of the community varies

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WATER SUPPLY PROJECT 2076 Batch

drastically from one 22 communities to another since every consumers consumes the
water as per their conveniences depending upon his/her habits which further depends on
season to season and other factors. Hence, the study of the consumption pattern is not
practical to do on each and every new project site. Therefore, the following consumption
pattern is tacitly assumed:
Intermittent /Intermittent System (peak factor = 1.5)
Time Period 5 to 8 AM 8 to 12 AM 12 to 17 AM 17 to 19 AM 19 to 5 AM
Percent Demand 40% 0% 0% 20% 40%

Reservoir Tank (RT) Sizing Cases: In the water distribution system, normally four cases
of reservoir size determination are practiced as shown in Table
Cases Inflow to the reservoir Outflow from the
reservoir
Case I Continuous Continuous
Case II Continuous Intermittent
Case III Intermittent Continuous
Case IV Intermittent Intermittent

6.8 Pipe line Design

6.8.1 System Flow Rate
In order to design the pipeline, the flow that each branch of the supply network has to
convey should be known. Once the tap flow rates in the stand posts are fixed, the system
flow rate automatically follows. Cumulative addition of tap flow rates to be served by the
pipe under consideration yields the system flow rate. A flow diagram of the scheme
should be prepared indicating the flow from each tap and the accumulated flow in the
branch and the main pipes. The flow required for various storage tanks has to be also
worked out at this stage.
6.8.2 Basis of designs
Once the flow, which a pipe section has to transmit is known, its diameter should be sized
next. The basis of pipe line design is governed by the theory of flow of water under
pressure in a pipe line, which is briefly discussed below.
Flow of water in pipe line results in loss of energy (head) during transmission. For a pipe
of length L, following factors govern the head loss:

The most rational formula that incorporates this entire factor is the Hazen William
equation which is as follows:

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WATER SUPPLY PROJECT 2076 Batch

HL/L = (10.659*Q1.85)/(C1.85*d4.86)
Where, HL = Head Loss, m
L = Length of Pipe, m
Q = discharge, m3/s
C = Hazen Williams coefficient
d = diameter of pipe, m

Hazen Williams Formula: Since the flow is turbulent in pipes used for water supply the
friction factors depend upon the roughness of the pipe and also upon Reynolds Number
which in turn depends in part upon the velocity in the pipe and its diameter. Hazen
Williams formula is most used in the design of water distribution network.
V= K (C) R0.63 S0.54
Where, V = Velocity in pipe, in m/s = Discharge, Q/Area
R = hydraulic radius in m = Flow Area/Wetted perimeter
S = hydraulic gradient = head loss/Length of pipe
C = a constant depending on the relative roughness of the pipe
K = a experimental coefficient, 0.849 in SI Units.

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WATER SUPPLY PROJECT 2076 Batch

6.9 Pipe network survey

Pipe network survey includes detailed engineering survey and population survey of the
entire service area.
Detailed Engineering Survey: The engineering survey of networks should be carried out
by leveling instrument and the detailed engineering survey should be carried out to
determine and fix:
-The network with loops
-Reduced levels of service reservoir site and source
-Reduced level of nodes
-Information about residential, industrial, commercial, institutional areas
-Information about storm water sewers, sanitary sewers and road intersections
The main aim of detailed engineering survey is to collect necessary data and information
for drawing street map of looped network of the service area.

6.10 Flow Velocity

While sizing the pipe diameter, minimum and maximum flow velocities in the selected
pipe should also be considered. Minimum velocity in the pipe line should be fixed to
wash sediment particles which should not be allowed to settle at any point. The velocity
must be sufficient to move sediment along with water. To destroy excess head, small sized
pipes are used, which however, increase the flow velocity. At velocities greater than 3 m/s
air and water tend to mix affecting flow and the head loss. Also at high velocities when
the faucets are suddenly closed the phenomenon of water hammer may also occur. (also
see section 4.8.4) Hence, the following minimum and maximum velocity limits should be
adopted.

6.11 Minimum Velocity

Transmission mains from stream intake to storage tank need special attention. This is
because river water may bring with it sediment particles that enter the supply line.
If no sedimentation tank is provided, the minimum flow velocity shall be:
in downhill stretches 0.8 m/s
in uphill stretches 1.0 m/s
If a sedimentation tank is provided on transmission main from stream intakes and for
transmission main for spring intake the minimum flow velocity can be reduced to :
in downhill stretches= 0.4 m/s
in uphill stretches = 0.5 m/s

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WATER SUPPLY PROJECT 2076 Batch

6.12 Maximum Velocity

When a valve is instantly closed, the maximum velocities in the pipes that may allow
water hammer pressure within the permissible limit of the pipe are theoretically obtained
as: on HDPE pipes class 6 kg/cm2: v = 2.3 m/s on HDPE pipe class 10 kg/cm2: v = 2.8
m/s A balance, thereof must be struck between destroying excess head and the danger of
creating a flow condition where high pressures due to water hammer can easily develop.
Hence, maximum velocity in pipelines should be restricted to:
-Desirable 2.5 m/s
- Exceptional 3.0 m/s

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WATER SUPPLY PROJECT 2076 Batch

7.0 Overhead tank design

7.1 Tank
Tanks are the structures constructed to hold any kind of liquids such as water, petroleum
and oil and so on. It can be made of different materials according to the location it is to be
placed and materials it needed to hold on. Some of the brief description is done below
about the tanks.
7.2 Types of water tank
Based on the location of the tank in a building's tanks can be classified into three
categories. These are:
 Underground tanks
 Tank resting on grounds
 Overhead tanks or Elevated tanks
7.3 Elevated Tank
Elevated tanks have many advantages. Elevated tanks do not require the continuous
operation of pumps. Short term pump shutdown does not affect water pressure in the
distribution system since the pressure is maintained by gravity. And strategic location of
the tank can equalize water pressures in the distribution system. However, precise water
pressure can be difficult to manage in some elevated tanks.
The pressure of the water flowing out of an elevated tank depends on the depth of the
water in the tank. A nearly empty tank probably will not provide enough pressure while a
completely full tank may provide too much pressure. The optimal pressure is achieved at
only one depth.
The optimal depth of water for the purpose of producing pressure is even more specific
for standpipes than for tanks elevated on legs. The length of the standpipe causes
continual and highly unequal pressures on the distribution system. In addition,a
significant quantity of the water in a standpipe is required to produce the necessary water
pressure.

7.4 Types of elevated water tank based on shape

 Circular tank
 Rectangular tank
 Intze tank

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7.5 Intze Tank

It is used to store large volumes of water at an elevation. Intze Tank essentially
consists of a Top Dome (roof), the cylindrical wall and the floor slab, which is a
combination of conical dome & bottom spherical dome.

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8. Water Sample Test

Water Sample Test

S. Uni NDWQ Remar

Parameter Sample
N. t S k

NT NHBG
0 5
1 Turbidity U V
NHBG
7 6.5 - 8.5
2 pH V
Colorles
3 Color s
Taste and NHBG
Normal Normal
4 Odor V
0
5 Temperature C 24.4
mg/ NHBG
0 0.3
6 Iron l V
mg/ NHBG
1.5 1.5
7 Ammonia l V
mg/ NHBG
500 250
8 Chloride l V

NDWQS - National Drinking Water Quality

Standards
NHBGV - Non-Health Based Guideline
Value

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9. Reservoir Sizing
Reservoir Tank Sizing

Time Period Hours

Water
I Water Inflow Surplus Deficit Remarks
From To Out Outflow
n
5 8 3 2 129600 113510 16090 0
8 12 0 0 0 0 0 0
12 17 0 0 0 0 0 0
17 19 1 1 43200 56755 0 13555
19 5 3 2 129600 113510 16090 0
Total 7 5 302400 283775 32180 13555

Storage Tank Capacity Provided = 40,000

ltr. (40m3)

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Estimation and Costing

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Estimation of Overhead Tank

Ite L or
No B A H Qty. Uni Remar
m Description D
. t k
no. m m m2 m

Upto Plinth
Beam
Earthwork
1 Excavation
Footing 1 4 12.56 1 12.560 m3

Brick Soiling in
2 Footing
Footing 1 4 12.56 12.560 m2

PCC Work in
3 Footing
Footing 1 4 12.56 0.1 1.256 m3

4 RCC Work
0.1
Footing 1 4 12.56 5 1.884 m3
Column 8 0.4 0.126 0.7 0.703 m3
0.65
Plinth Beam 8 8 0.3 0.3 0.474 m3
Total 3.061 m3

Brick Work in
5 Footing
0.65
Below GL 8 8 0.3 0.7 1.105 m3

6 Back Filling
Below GL
Total excavation 12.560 m3
Deduction
Volume of Brick 0.0
soiling 5 0.628 m3
Volume of PCC
work 1.256 m3
Volume of RCC
work 3.061 m3
Volume of Brick
work 1.105 m3
Total 6.509 m3

7 Formwork

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Column 8 0.4 1.256 0.7 7.034 m2

1.31
Plinth Beam 8 6 0.3 3.158 m2

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Ite L or
B A H Qty
m Description No. D Unit Remark
no. m m m2 m

Above Plinth
Level
1 RCC work
0.12
Column 32 0.4 6 3 12.058 m3
0.65
Braces 24 8 0.3 0.3 1.421 m3
Circular Ring 0.65
Beam 8 8 0.3 0.3 0.474 m3
Bottom Dome 1 0.959 m3
Conical Dome 1 0.2 2.227 m3
1.53
Bottom Ring Beam 8 8 0.23 0.23 0.651 m3
12.5
Circular Side Wall 1 6 0.15 3.5 6.594 m3
1.53
Top Ring Beam 8 8 0.23 0.23 0.651 m3
Top Dome 1 4 1.321 m3
Total 26.355 m3

2 Formwork
1.25
Column 32 0.4 6 3 120.576 m2
Except Column
0.65
Braces 24 8 0.3 0.3 14.213 m2
Circular Ring 0.65
Beam 8 8 0.3 0.3 4.738 m2
Bottom Dome 1 6.531 m2
Conical Dome 1 11.134 m2
1.53
Bottom Ring Beam 8 8 0.23 0.23 8.490 m2
Circular Side Wall 1 4 0.15 3.5 84.623 m2
1.53
Top Ring Beam 8 8 0.23 0.23 8.490 m2
Top Dome 1 4 14.570 m2
Total 152.787 m2

3 Plastering
Ceiling
0.65
Braces 24 8 0.3 4.738 m2
Circular Ring 0.65
Beam 8 8 0.3 1.579 m2

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Bottom Dome 1 6.531 m2

1.53
Bottom Ring Beam 8 8 0.23 2.830 m2
1.53
Top Ring Beam 8 8 0.23 2.830 m2
Top Dome 1 4 14.570 m2
Total 33.077 m2

Except Ceiling
1.25
Column 32 0.4 6 3 120.576 m2
0.65
Braces 24 8 0.3 9.475 m2
Circular Ring 0.65
Beam 8 8 0.3 3.158 m2
Bottom Dome 1 7.662 m2
Ite L or
No B A H Quantit Remark
m Description D Unit
. y s
no. m m m2 m

Conical Dome 1 22.267 m2

1.53
Bottom Ring Beam 8 8 0.23 5.660 m2
0.1
Circular Side Wall 1 4 5 3.5 84.623 m2
1.53
Top Ring Beam 8 8 0.23 5.660 m2
Top Dome 1 4 15.103 m2
Total 274.184 m2

4 Coloring
Column 32 0.4 1.256 3 120.576 m2
0.65
Braces 24 8 0.3 0.3 18.950 m2
0.65
Circular Ring Beam 8 8 0.3 0.3 4.738 m2
Bottom Dome 1 6.531 m2
Conical Dome 1 11.134 m2
1.53 0.2
Bottom Ring Beam 8 8 3 0.23 11.320 m2
12.5
Circular Side Wall 1 6 3.5 43.960 m2
1.53 0.2
Top Ring Beam 8 8 3 0.23 11.320 m2
Top Dome 1 4 15.103 m2
Total 243.632 m2

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Drawings
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