By: Eng. Ayman Afifi
March 2009
Water System
 Any System consists mainly of the following three phases:
Input
Processing
Output
System Efficiency
The ability of an existing or planned water supply and distribution system
to perform adequately - that is, to fulfill appropriately its intended purpose
- under the widest possible range of likely operating condition, particularly
those that are expected to occur during its working life, is a crucial system
characteristic.
Output
Efficiency( ) 
 100%
Input
2
Water System Capacity
•Technical capacity means that the water system has the necessary
technical infrastructure and competent trained staff needed to comply
with drinking water regulations.
•Financial capacity means that the water system possesses the
financial resources needed to comply with drinking water requirements
for both the short and long term.
•Managerial capacity means that the water system has the institutional
and administrative resources needed to comply with drinking water
regulations
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Types of transmitted water :
1. Clean water:
• Source: Water wells, lakes,..etc.
• Transportation system: mostly under pressure (using pumps).
2. Wastewater:
• Source: domestic, agriculture, industrial usage.
• Transportation system: by gravity.
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Water Distribution System
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Sources of Potable Water
Untreated water (also called raw water)
may come from groundwater sources or
surface waters such as lakes, reservoirs,
and rivers. The raw water is usually
transported to a water treatment plant,
where it is processed to produce treated
water (also known as potable or finished
water).
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Transport Facilities
Moving water from the source to the
customer requires a network of pipes,
pumps, valves, and other
appurtenances. Storing water to
accommodate fluctuations in demand
due to varying rates of usage or fire
protection needs requires storage
facilities such as tanks and reservoirs.
Piping, storage, and the supporting
infrastructure are together referred to as
the water distribution system (WDS).
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Water Distribution System

Components of distribution network:
1.
Wells.
Reservoirs.
Pipelines.
Booster pumps.
Valves.
2.
3.
4.
5.
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Types of Water Distribution System
1.
2.
3.
Gravity system.
Pumping system.
Pumping system with storage.
The aim of all these systems is to obtain an adequate
pressure at various points in the distribution system. The
choice of the system depends upon the topography of the
area of distribution and its elevation with reference to the
source of the supply.
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Gravity Systems

This system is the most dependable technique
provided. There are multiple well-protected
conduits carrying the flow to the community.

The gravity system is the most reliable. This
system is useful in hilly areas where the source
of supply is located substantially above the
level of the city, such that adequate pressure is
obtained in the network directly.
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Gravity Systems
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Gravity Systems
Advantages
1.
No energy costs.
2.
Simple operation
3.
Low maintenance costs.
4.
No sudden pressure to
changes.
Disadvantages
1.
2.
3.
4.
Gravity system is less flexible
for future extension.
Small gradients available for
friction losses require large
diameters within the whole
system.
Longer pipelines are
necessary.
High pressure for fire fighting
requires use of motor pumping.
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Pumping Without Storage System

Pumped supply systems operate without or
with limited water storage (water towers) in the
distribution system. With direct pumping to
the system, they have to follow variations in
water demand. Proper selections of units have
to be done in order to optimize energy
consumption, including reserve-pumping for
irregular situations.
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3
Pumping Without Storage System
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Pumping Without Storage System
Advantages
1.
Permitting increased pressure
for fire fighting.
Disadvantages
1.
2.
3.
Power failure and pressure will
fluctuate substantially with
variation in flow.
The flow must be constantly
varied to match an
unpredictable demand.
Increasing power costs.
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Pumping With Storage System

It is the most common method of distribution. Water is pumped at
a more or less uniform rate with flow in excess of consumption
being stored in elevated storage tanks distributed throughout the
system. During periods of high demand, the stored water
augments the pumped flow, thus helping to equalize the pumping
rate and maintain more uniform pressure in the system.

Advantages:
Economical to pump only during off-peak hour to minimize powering
costs
Pumping with storage system is the most common system for large
distribution areas.
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Pumping With Storage System
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Methods of supply of water
Water can be supplied to the consumers by the
following two systems:


Continuous system.
Intermittent system.
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Continuous system

In this system of supply, water is supplied to the
consumers all the twenty- four hours. This system is
possible only when there is sufficient quantity of water
available from the source.
Advantages of continuous system:

Consumers don’t have to store water, since it is
continuously available at the tap.

Water always remains available for fire fighting.
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Intermitted system

In this system of supply, water is supplied to the consumers only in
pre-selected hours during the day. Hours of supply depends on
demand, culture and distribution of needs.
Advantages of intermitted system:

Provide only needed water.

Less central storage tank volume needed.
Disadvantages of the intermitted system:

On house storage is obligatory.

Water quality in house tanks is affected with time.

Pipe diameters are larger than the ones used in continuous system.

Too many valves are needed in the system.
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Configuration of Distribution Networks
1. Serial network
This network is without branches or loops. It has one source, one dead
end and a couple of intermediate demand nodes. It’s usually used in unorganized developed cities.
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Serial Network
Advantages of the Serial Network:
 Pressure and flow can be easily calculated at any point.
 Few valves are required to keep the system working.
 Pipe diameters are calculated relatively to the existing population.
Disadvantages of the Serial Network:
 Maintenance works cause termination of the water supply in the
whole system.
 Dead-ends increase pressure at the system which may cause, if
exploded, a huge damages that could affect the entire efficiency of the
system.
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Configuration of Distribution Networks
2. Grid network
Consists of demand points that are supplied from more than one pipe.
Flow direction is determined by the system operation and much less by
its layout, thus it is not fixed which means that the location of critical
points may vary in time.
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Grid network
Advantages of the Serial Network:
 Maintenance work is much easier and cause no break to the entire
system.
 Water for emergencies like fire is easier to provide by controlling the
valves in the system.
 Less energy loss and adequate water pressure.
Disadvantages of the Serial Network:
 Cost a lot due the number of pipes and network fittings.
 Water pressure at every point is always varying with time and
relatively connected to the water consumption.
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Questions