Water resources project
analysis of water distribution
system and its maintainance
What is a water supply network ?
• A water supply system or water distribution
engineered hydrologic and hydraulic componen
ts which provide water supply.
Types of distribution systems
There are basically two main layouts of a distribution
• Branched configuration
• Looped (or ”grid”) configuration
• Branched configuration
Branched networks are predominantly used for
small-capacity community supplies
delivering the water mostly through public
standpipes and having few house
connections, if any. Although adequate, having
in mind simplicity and acceptable
investment costs, branched networks have
• Looped (or ”grid”) configuration
A looped network usually has a skeleton of
secondary mains that can also be in a form
of branch, one loop (’ring’), or a number of
loops. From there, the water is conveyed
towards the distribution pipes and further
to the consumers. The secondary mains are
connected to one or more loops or rings.
The network in large (urban) distribution
systems will be much more complex
essentially a combination of loops and
branches with lots of interconnected pipes
that requires many valves and special
What does a water supply system
include ?• A drainage basin .
• A raw water collection point (above or below ground) where the water accumulates,
such as a lake, a river, or groundwaterfrom an underground aquifer. Raw water may be
transferred using uncovered ground-level aqueducts, covered tunnels or
underground water pipes to water purification facilities.
• Water purification facilities. Treated water is transferred using water pipes (usually
• Water storage facilities such as reservoirs, water tanks, or water towers. Smaller
water systems may store the water in cisternsor pressure vessels. Tall buildings may
also need to store water locally in pressure vessels in order for the water to reach
the upper floors.
• Additional water pressurizing components such as pumping stations may need to be
situated at the outlet of underground or above ground reservoirs or cisterns (if
gravity flow is impractical).
• A pipe network for distribution of water to the consumers (which may be private
houses or industrial, commercial or institution establishments) and other usage points
(such as fire hydrants).
• Connections to the sewers (underground pipes, or aboveground ditches in some
developing countries) are generally found downstream of the water consumers, but
the sewer system is considered to be a separate system, rather than part of the
water supply system.
water distribution system
• It is a very simple method of water
distribution. Calculations are easy and simple
• The required dimensions of the pipes are
• This method requires comparatively less
number of cut-off valves.
• The area receiving water from a pipe under repair is without water until
the work is completed.
• In this system, there are large number of dead ends where water does
not circulate but remains static.
• Sediments accumulate due to stagnation of the dead end and bacterial
• growth may occur at these points. To overcome this problem drain valves
• at dead ends and stagnant water is drained out by periodically opening
these valves but a large amount of water is wasted.
• It is difficult to maintain chlorine residual at the dead ends of the pipe.
• Water available for fire-fighting will be limited since it is being supplied
by only one water main.
• The pressure at the end of the line may become undesirably low as
additional areas are connected to the water supply system. This problem
is common in many less-developed countries.
Maintainance of water distribution
• Here are a few of the points covering the
1. pipeline Maintainance system
• A pipeline maintenance system must ensure that all
required maintenance work can be carried out with
ease. The system is actually determined by the scale
and type of facilities, the number of employees, and
other aspects, but the system must also be able to
cope with operation under both normal and emergency
1. Normal operation
1.1 Facility patrols and inspection
Capital equipment and personnel qualified to conduct
periodic patrols, inspections, servicing and surveys must
be provided in order to prevent pipeline accidents from
1.2 Pipeline drawing preparation
Pipeline drawings are essential for the maintenance of
pipelines, and they must be absolutely correct because
they are used on regular basis. This is why pipeline
drawings must be prepared, and a system for their
control must be established.
2. Emergency operations
Pipeline leaks may cause flooding of homes, traffic accidents and
traffic jams due to sunken roads, insufficient flow, and turbid
water. In order to minimize such damage when a leak occurs, a
system must be in place to initiate repairs immediately. As part of
the system, it is a good idea to establish a stand-by system or an
on-duty system organized into a cohesive unit that can respond in
the event of an emergency.
3. Night and holiday dispatch
A dispatch system must be established for nights and holidays
since leaks can occur just as well outside business hours. In
order to prepare for unexpected accidents, a mobilization plan
must be set up ahead of time that designates essential
restoration personnel and outlines notification arrangements
so personnel can be summoned immediately and assigned to
departments and sections.
4. On-call contractors
In order for designated contractors to perform repair work, there
must be a system of contractors, a method for designating
emergencies, and annual contracts signed for handling accidents. An
emergency call-out system must be established using a shift system
that includes a number of companies, and a base must be set up with
permanently stationed communications personnel to cope with
unexpected accidents at any time, including nights and holidays.
5. Emergency water supply
Water wagons and portable cans must be prepared to provide
emergency supplies to areas cut off from water. Coupling to
distribution pipes in surrounding areas and neighbouring cities as
well as other measures are highly desirable for providing immediate
water supply assistance in order to keep the area cut off from water
to an absolute minimum.
6.Equipment and repair material preparation
Spare pipes for repairs organized by type and diameter as well as
restoration machines and equipment must be kept in a constant state
of readiness. In particular, a chart showing the amount of materials
stored for emergency, a chart summarizing work equipment, an
emergency mobilization plan and a work division chart must be
prepared and inspected periodically each year. Ideally, materials
stored for an emergency will be shared by neighbouring cities
How to carry out Maintainance ??
• 1. the flushing of water pipes should be carried out whereever
necessary especially in case of dead ends on lines and at places where
water is supplied without filtration
• 2. the hydrants valves and various other appurtenances installed on the
water mains should be checked regualrly and should be maintained in
perfect running order.
• 3. the records regarding the lengths of pipes laid , lengths of pipes
repaired or replaced expenditure incurred , number of fire hydrants ,
number of service connections and all other relevant data in connection
with the distribution system should be well maintained.
• 4. the wastage of water especially of leakage through pipe joints should
be brought down to minimum possible extent .
• 5. the water pipes should be cleaned periodically by use of scrapping
• 6. meters installed on distribution system should be checked from time
to time and the defective or unreliable meters should be
immediately replaced or repaired.
Leakage control and maintainance
• There is a constant danger of leaks occurring because
pipelines are exposed to various types of construction
work, traffic loads, corrosion, uneven settling of the
ground and earthquakes; and the pipes themselves
suffer from ageing. Frequent leaks can have a major
impact on the lives of citizens not only because of
water shutoffs and reduced water flow, but roads
and other underground facilities may be damaged or
homes may be flooded. This is why it is so important
to constantly patrol pipelines and inspect facilities in
order to prevent leaks or to find them as quickly as
The factors influencing leakage are ;
• soil characteristics, soil movement, traffic
• defects in pipes, poor quality of joints
• poor quality of workmanship, damage due to
excavation for other purposes
• pipe age and corrosion level
• high pressures in the system
• extreme temperatures
Corrosion of metal pipes is one of the major causes of poor operation
distribution systems. It appears as a result of reaction between the
water and metal. This
internal corrosion causes three problems:
• The pipe mass is lost through oxidation to soluble iron, resulting in
increased rate of
• The second by-product of oxidation is iron-bearing scale that
accumulates on the
pipe wall in the form of tubercles, causing a reduction of pipe capacity
• Both soluble and particulate iron affects the water quality creating
(‘brown’ or ‘red’ water)
External corrosion is a result of aggressive soils and may also
contribute to the pipe burst rate to a large extent.