Water Supply Systems
Lecture notes 1
dr Patryk Wjtowicz
Monday 1 December 14
Contents
Introduction to water distribution systems
History and evolution of water supply systems
Primary function and design criteria of WDS
Anatomy of water supply systems
Layouts of water distribution system
Criteria and classification of water systems
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Water distribution system*
Water distribution system (WDS) is a network of
pipelines and structures that distribute water to
the consumers
WDS is designed to adequately satisfy the water
requirement for a combination of purposes:
Domestic
Commercial
Industrial
Firefighting purposes
(*also: Water Supply System - WSS)
Monday 1 December 14
History of water distribution systems
The oldest water distribution systems discovered on the island of
Crete are 3500 years old (first usage of pipes). The City of Knossos
develops an aqueduct system that uses tubular conduits to convey
water. Other ancient civilizations have had surface water canals,
but these are probably the first pipes
a) Closed/ pressured pipe system. The advanced urban water distribution system of the
250 B.C. - Archimedes principle developed
closed type in the Minoan palaces and settlements is very interesting. The evidence
100 A.D. - Roman aqueducts
for it in Minoan Crete comes from the use of terracotta pipes, found at the palace of
Knossos and Tylissos, along with several others, albeit in bad condition, at the palace
of Phaistos and at Palaikastro, Gournia, Lykastos and Zakro (House B). Among them
the best patterns are those of the palace at Knossos, belonging to the earliest middle
period and at Tylissos, assigned to the earliest late period although an earlier date has
also been proposed for it (Angelakis et al., 2005).
0.72
0.025
0.17
0.085
0.065
Figure 1. Minoan water transfer projects: The proposed course (A- B) of the aqueduct at Knossos with
higher spring elevation (Angelakis et al., 2007) (left) and water supply pipes (terracotta pipe sections):
cross section and dimensions (upper) and today view (down) (Koutsoyiannis et al., 2008) (right).
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Hellenistic Period (ca. 323-67 B. C.)
During the succeeding Hellenistic period, impressive accomplishments were also achieved in
History of water distribution systems
Early pipelines were made by drilling stones,
wood, clay and lead
1455 - first cast iron pipe
wooden pipes
ceramic pipelines
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History of water distribution systems
1664 - Palace of Versailles: 35 km long cast iron
water main (flanged joints) from Marly-on-Seine
to the Palace of Versailles (still in operation).
Used for 1400 fountains of Sun King Louis XIV
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History of water distribution systems
1738 Bernoulli publishes Hydrodynamica.
1920s Cement-mortar lining of water mains
1770 Chezy develops head loss relationship
1845 Darcy-Weisbach head loss equation
developed
1936 Hardy Cross method developed
1938 Colebrook-White equation developed
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History of water distribution systems
1960s and 70s Earliest pipe network digital
models created
1980 Personal computers introduced
2001 Automated calibration
2002 Integration with GIS
Section 1.5
A Brief History of Water Distribution Technology
language, researchers at universities begin to develop pipe network models and make
them available to practicing engineers. Don Wood at the University of Kentucky, Al
Fowler at the University of British Columbia, Roland Jeppson of Utah State University, Chuck Howard and Uri Shamir at MIT, and Simsek Sarikelle at the University of
Akron all write pipe network models.
Figure
A compu
card
A computer punch card
1963 First U.S. PVC pipe standards. The National Bureau of Standards accepts
CS256-63 Commercial Standard for PVC Plastic Pipes (SDR-PR and Class T),
which is the first U.S. standard for polyvinyl chloride water pipe.
Monday 1 December 14
1963 URISA is founded. The Urban and Regional Information Systems Associa-
Primary function of WDS
The purpose of the water distribution system is to
deliver water to consumer with appropriate quality,
quantity and pressure
Distribution systems typically also provide storage,
as well as provide flow and pressure adequate for
fire protection.
Brewer Secretly Rigs Plumbing in Man's House to Make Beer Flow From Every Tap
Monday 1 December 14
System design criteria
Water quality should not get deteriorated in the main
and distribution pipelines on the way from the treatment
facility to the customer
System should be capable of supplying water to all
intended (and planned) places with sufficient pressure
head
System should be also capable of supplying the required
amount of water during fire fighting
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System design criteria contd.
The layout of the system should be such that no
consumer would be without water supply, during the
repair or maintenance of any section of the water
network
All the distribution pipelines should be preferably laid
above the sewer lines
Pipes should be water-tight to keep water losses due
to leakage to the minimum
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System configuration - anatomy of WDS
rivers, lakes, springs
man-made reservoirs
groundwater sources (bores and wells)
intake structures and pumping stations
to extract water from source
water is carried over long distances through
transmission mains
pumping main if pressure head is created by
pumping
gravity main if flow maintained by gravitational
potential (on account of elevation dierence)
There are no intermediate withdrawals
water sources and intake
works
transmission mains
Water distribution system
treatment works and
storage
raw water is transported to treatment plant for
processing
water after treatment is stored in clear water
reservoirs
water reservoirs provides a buer for water demand
variation (treatment plant is designed for average daily
demand)
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distribution network
distribution network delivers water to
consumers through service connections
water distribution network may have
dierent layout (branched or looped)
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WATER DISTRIBUTION
SYSTEM
PUMPING STATION
STRUCTURAL
ELECTRICAL
PUMP
DRIVER
DISTRIBUTION
STORAGE
PUMPING
PIPING
POWER
TRANSMISSION
TANKS
CONTROLS
PIPE
SYSTEM
DISTRIBUTION
PIPING
VALVE
PIPES
VALVES
COMPONENTS
SUBCOMPONENTS
SUB-SUB COMPONENTS
FIGURE 1.15 Hierarchical relationship of components, subcomponents, and sub-subcomponents for a water distribution system (Cullinane, 1989).
Monday 1 December 14
Distribution System Layout
Water distribution mains may IRC_SCWS-book
be laid out
in 20-11-2002
grids, loops,
or branches
(much
27 gtb
14:58 Pagina
467
like a tree). Two basic types can be distinguished:
IRC_SCWS-book 27 gtb 20-11-2002 14:58 Pagina 467
Branched (dead-end) network
layout
Looped network
Chapter 21
layout
Chapter 21
Usually we have a mix of
branched and looped
layouts - depends heavily on
the history and general layout
plan of the city roads and
streets
Grid
or loop systems provide greater
Branched layouts result in a number of
flow for fire protection
and reduce the
Fig. 21.1. Types of distribution systems
Fig. 21.1. Types of distribution systems
dead-end lines that can lead to
number
ofpossibility
dead-end
lines
Danger of contamination caused by the possibility that a large part
of network
will
Danger
of
contamination
caused
by
the
that
a
large
part of network will
bacteriological,
taste,
and
odor
problems
be without water during irregular situations
be without water during irregular situations
Accumulation
due more
to stagnation
of the water at the
ends
theyof sediments,
require
frequent
In addition,
system
Accumulation
of sediments, due to stagnation of the water at the system ends
ends) occasionally resulting in taste and odour problems (dead ends) occasionally resulting in taste and odour problems
flushing (dead
Fluctuating water demand producing rather large pressure variations
Fluctuating water demand producing rather large pressure variations
Branched
and the flow rates
Monday 1 December
14 systems are easy to design. The direction of the water flow
Branched systems are easy to design. The direction of the water flow and the flow rates
Layout of network
Urban water networks have mostly looped
configurations
Rural water networks have branched (dead-end)
configurations
The cost of a WDS depends upon proper
selection of the geometry of the network. The
selection of street layout adopted in the city
planning is important to provide a minimum-cost
water supply system
Monday 1 December 14
Advantages of the branched pattern
The design calculation is simple and easy
A smaller number of cut-off valves are required
and the operation and maintenance cost is low
Pipe-laying is simple
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Disadvantages of the branched pattern
The system is less successful in maintaining satisfactory pressure in the
remote areas
and is therefore not favoured in modern waterworks practice
One main pipeline provides the entire city, which is quite risky. Any defect,
damage
or breakage at one point of this line will disrupt the supply of water beyond
that point, cutting off service to the whole area. This could be dangerous,
especially if there is a fire
The head loss is relatively high, requiring larger pipe diameter, and/or larger
capacities for pumping units. Water hammer could also cause burst of lines
Dead ends at line terminals might affect the quality of water by allowing
sedimentation and encouraging bacterial growth due to stagnation
A large number of scour valves are required at the dead ends, which need
to be opened periodically for the removal of stale water and sediment
The discharge available for fire fighting in the streets will be limited due to
high head loss in areas with weak pressure
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Looped network configurations patterns
The most common water supply configurations
of looped water supply systems are:
gridiron pattern
circular or ring pattern
radial pattern
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Gridiron pattern
In the gridiron system the main supply line runs through the
center of the area and sub- mains takeoff from this in perpendicular
directions
The branch lines interconnect the sub-mains
All of the pipelines are interconnected and there are no dead ends
This system is ideal for cities laid out in a rectangular plan (e.g.
New York, most city centres)
Water can reach a given point of withdrawal from several directions
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Advantages of gridiron pattern
The free circulation of water, without any stagnation
or sediment deposit, minimizes the the chances of
pollution due to stagnation
Water is available at every point, with minimum loss
of head, because of the pipeline interconnections
Enough water is available at streets fire hydrants,
as the hydrant will draw water from the various
branches of water lines
During repairs, only a small area of distribution is
affected
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Disadvantages of gridiron pattern
A large number of cut-off valves are required
The system requires longer pipe lengths with
larger diameters
The hydraulic calculations of discharge,
pressure and velocities in the pipes is difficult
and inconvenient
The cost of pipe-laying is higher
Monday 1 December 14
Circular (ring) pattern
WATER SUPPLY SYSTEMS VOL. I: SYSTEM CONCEPTS
CHAPTER 4: WATER DISTRIBUTION SYSTEM DESIGN CONCEPTS
In circular (also ring) pattern the supply main forms a ring
around the distribution area
The branches are connected cross-wise to the mains and also
to each other
Circular pattern is most reliable for a town with well planned
streets and roads
Figure 4-7: Layout of a Typical Looped Water Distribution System
It is important to note that many older water systems have been updated. By laying a primary feeder
around the perimeter of the community to tie in all of the dead-end mains to improve both flow
distribution and water pressures through the community. A simple example of this concept is presented in
Figure 4-8.
Figure 4-8: Typical Small City Distribution System
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Advantages and disadvantages of circular pattern
The advantages and disadvantages of circular
system are the same as those of the gridiron
system
Only in case of fire, a larger quantity of water is
available, because the available length of the
distribution main is much larger
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Radial pattern
In a radial system, the whole area is divided into a number of
distribution districts
Each district has a centrally located distribution reservoir (elevated)
from where distribution pipes run radially towards the periphery of the
distribution district
This system provides swift service, without much loss of head
The design calculations are much simpler
Monday 1 December 14
Water systems classifications - water pressure
criterion
There are two basic types of water supply systems to
create water pressure within the distribution system:
Gravity feed systems
Pumping pressure systems
tertiary pumping station (or
booster station)
primary pumping
station
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secondary pumping station
Gravity water distribution
Gravity distribution is possible when the treated water
source is located at some needed elevation above the
supplied community
In this type of system, sufficient pressure is available due to
gravity to maintain water pressure in the mains for domestic
consumption and fire service demand.
This is the most reliable and economical method of
distribution
Higher pressures for firefighting, however, requires the use
of mobile fire department pumpers and, in some cases,
stationary booster pumps on the water system to provide
needed fire flows at representative fire hydrants with a
required residual pressure
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Pumps and elevated storage
Through the use of pumps and elevated storage,
the excess water pumped during periods of low
consumption is stored in elevated tanks or
reservoirs
During periods of high consumption, the stored
water supplements the water that is being pumped
This method allows fairly uniform flow rates and
pressures throughout the water system
Since the stored water supplements the supply
used for fires and system breakdowns, this method
of operation is fairly reliable
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Pumps without storage
When stationary pumps are used to distribute water, and no
storage is provided on the distribution system, the pumps force
water at the required volume and pressure directly into the mains
This is the least desirable type of distribution system because a
power failure could interrupt the water supply
As water consumption varies, the pressure in the water mains is
most likely to fluctuate
To conform to varying rates, several pumps are made available to
add water output when needed, a procedure requiring reliable
and tested automated control at the water plant
Another disadvantage is the fact that the peak power demand of
the water plant is likely to occur during periods of high electric
power consumption, thus increasing power costs to operate the
water system
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Classification of water distribution systems - water
source criterion
Community water systems can be divided into four basic
classifications according to the water source:
High or low reservoirs that hold water for gravity feed
Pumps at well sites that pump water to the treatment facility.
Based on the difference in elevation between the treatment facility
and the community to be served, the water may flow by gravity
through the distribution systems, or there may be the need for
another pumping station
A combination of gravity flow and one or more pumping
stations to transport the water from the source point to all of the
water demand points on the distribution system
Pumping station systems where the raw water is pumped from
the source point to the treatment plant and then either pumped
directly into the distribution system or into storage to be used on
demand by the community
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High-level reservoir system
In a high-level reservoir system a water source must be at proper elevation above the
treatment facility in order to provide sufficient head pressure so that no pumping station is
required (usually at least 30 meters)
If there is sufficient elevation difference between the treatment facility and the distribution piping
in the community, it is possible to design a water system that does not require pumping stations
The head pressure for supplying water to the distribution system must be sufficient to meet both
consumer demand and needed fire flows at any conditions
Gravity feed systems are highly reliable under all weather conditions that may cause disruption to
the pumped systems. There is no mechanical component to break down or fail when the power
source goes down.
W
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This is a very economical
system
since there is noC substantial
power
requirement to run the
water system
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ATER
UPPLY
YSTEMS
OL
YSTEM
ONCEPTS
HAPTER
Figure 4-2
ATER
ISTRIBUTION
YSTEM
ESIGN
ONCEPTS
Low level reservoir systems
A low level reservoir systems typically require a pumping station to
transport water to the treatment plant
If the land area is relatively flat, a second pumping station to pump
treated water directly to the distribution system or to elevated storage
to provide the required pressure and volume to meet instantaneous
flow demand
The elevated storage can be designed to minimize the direct pumping
W
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requirements
Monday 1 December 14
ATER
UPPLY
YSTEMS
OL
YSTEM
ONCEPTS
HAPTER
ATER
ISTRIBUTION
YSTEM
ESIGN
ONCEPTS
Direct pumping systems
Direct pumping systems feeds water to the
treatment plant and then a second pumping system
transports water to a storage
holding
area
(clear
well,
Figure 4-3
standpipe storage tank)
3) Direct pumping systems: Figure 4-4 illustrates how a direct pumping station feeds water to the
treatment plant and then a second pumping system transports water to a storage holding area, such as a
clear well, to a standpipe storage tank that is maintained full as domestic consumption varies throughout
a single day. This minimizes the time the pump or pumps actually have to run. The pumps also may be
designed and arranged to pump the treated water directly into the distribution system when there is a
high demand on the water system. This could occur when there is a major fire in the community.
This combination of pipe and tank minimizes the time
the pump or pumps actually have to run
FILTRATION
PLANT
PUMP STATION
WELL
CASING
Monday 1 December 14
PUMP STATION
DISTRIBUTION
SYSTEM
Pumping station at well sites + gravity storage
WATER SUPPLY SYSTEMS VOL. I: SYSTEM CONCEPTS
CHAPTER 4: WATER DISTRIBUTION SYSTEM DESIGN CONCEPTS
4) Pumping station at well sites and gravity storage: In this type of supply system, one drilled well, or
a field of wells, feed water to a ground-level pumping station. This concept is presented in Figure 4-5.
Chapter 3 indicates that the water treatment for ground water supplies may be less rigorous than for
surface water supplies. The quality of the ground water in many areas of the country is so good that
the only treatment necessary is chlorination through an injection method in the pipes that carry the
non-potable water. In most cases, any other required water treatment generally is handled in a similar
manner. The treated water either flows by gravity to the distribution system or is pumped to one or
more elevated storage tanks. Potable water flows by gravity from the storage tank to the distribution
system. Small communities that essentially operate off individual wells might want to consider this
type of system. This is a more efficient way to provide water that is reliable year round, and is a
system that can meet both consumer demands and needed fire flow requirements. This concept should
be investigated with reference to the reduction in fire insurance premiums as the result of having a
recognized water delivery system.
In pumping station from well sites to a gravity storage, one or
a field of drilled well, feed water to a ground-level pumping station
The treated water either flows by gravity to the distribution system
or is pumped to one or more elevated storage tanks
Elevated tanks may be located at the beginning, centre or end of
water network
Monday 1 December 14
Composite water supply systems
In some specific conditions of areas served by the water system, especially
topography may require using a composite system (mixed type) that uses
components from more than one of the typical water systems
Examples of mixed water supply systems:
Adding pumping stations to a gravity reservoir system to increase
pressure and volume during peak demand periods (esp. for a fire flow
requirement)
Booster pumping stations may be installed where there is a need for
more than one service level based on pressure demand
Direct pumping into the distribution system may be supplemented by
gravity tanks that "float" on the system to maintain pressure and flow
characteristics during different demand periods through the day and
night
Gravity tanks are especially useful for improving the reliability of any
water system, care must be taken to allow for proper mixing of water
stored
Monday 1 December 14
Systemy strefowe
Monday 1 December 14
Supplementary reading
Larry Mays (2000) Water Distribution System
Handbook, Chapter 1, McGraw-Hill, New York.
Assignment:
Prepare short paper (4 A4 pages) summarizing
all important information from supplementary
reading.
Paper should include introduction and several
subchapters.
Monday 1 December 14
Literature
Mays et al. (2000) Water distribution systems handbook,
McGraw-Hill, New York.
Savic et al. (2011) Water distribution systems, ICE
Publishing, Thomas Telford Ltd, London.
Swamee and Sharma (2008) Design of water supply pipe
networks, Wiley.
Computer Modeling of Water Distribution Systems - Manual
of Water Supply Practices, M32 (3rd Edition). American
Water Works Association (AWWA).
Online version available at: http://app.knovel.com/hotlink/
toc/id:kpCMWDSM0G/computer-modeling-water/computermodeling-water
Monday 1 December 14
