Introduction:
The distribution system is a network of pipe lines inside
the municipal limit, for transporting purified water to the consumers. The
consumers may be general public’s individual house, estates, industries and
public places. The distribution system consists of large size mains arterial
mains of intermediate size and minor distributors together with valves,
hydrants, service connections etc. Pumps are also required to pump water
directly into the mains or to the elevated reservoirs.
Distribution system:
The main purpose of the distribution system is to developed
adequate water pressure at the consumer’s taps.
The distribution systems may be classified in three
categories:
u Gravity system
u Pumping system without storage
u Dual system with storage
Gravity system :
In this system, the elevation of the source of supply in
relation to the area of distribution is kept such that adequate water pressure
in the pipes at different points is available. In this system, pumping is
normally not required.
Pumping system without storage:
In this system, purified water is directly pumped into the
distributing mains for obtaining the required pressure, Sometimes, double
pumping is required, first to pump raw water to the treatment works and
secondly, the treated water into the mains.
u The
pumps will have to be run at varying speeds and thus necessitate constant
attendance on pumps.
u Pumps
also wear out in very short time.
u It
is the most undesirable systems because power failure would mean complete
interruption in the water supply.
Pumping system with storage (Dual system):
This system is nothing but a combination of gravity and
pumping systems. In this system, the excess of water pumped during periods of
low consumption is stored in elevated tanks. As the time of high consumption,
the stored water in the elevated tanks augments the pumping and peak demand is
fulfilled.
This method is more reliable and economical. Stored water in
elevated tanks also fulfills water requirements for sometimes during break down
of pumps and for fire fighting. This method of distribution is usually
applicable in most of the cases.
Advantages:
u Pumps are run at uniform rate and thus less
wear and tear.
u It is more reliable, because even during break
downs in pumps, pipes, etc. some quantity of water remains available for some
time from the elevated reservoir.
Method of supply of water :
Water can be supplied to the consumers by the following two
systems:
(a) Continuous
system
(b) Intermittent system
Continuous system :
In this system of supply, water is supplied to the
consumer’s all the 24-hours. It is the most ideal system and as far as
possible, it should only be adopted.
Advantages:
u Consumers
don’t have to store water, since it is continuously available at the tap.
u Water
always remains available for fire fighting.
u Wastage
of water is less.
u Air
relief or pressure relief valves and scour valves are not required because due
to constant circulation of water in the pipe, accumulation of air and
sedimentation do not take place.
u Small
size pipes will be required.
u Due
to continuous circulation, water always remains fresh.
Disadvantages:
u This system is possible only when there is
sufficient quantity of water available from the source.
u More wastage of water if the people using it
do not process civic sense and don’t understand importance of treated water.
Intermittent system :
In this system, water is supplied only during certain fixed
hours of the day, which are normally morning and evening hours. Intermittent
supply is provided when the quantity of available water from the source is not
sufficient to meet the demands of continuous supply.
Advantages:
u This
system is suitable when water from the source is available is limited amount.
u Since
people make storage tanks in their homes for non supply hours, it is possible
for them to pull on with stored water for a day or two in emergencies.
Disadvantages:
u Consumers
have to some water for non supply hours.
u People
have to construct storage tanks at their homes which add to the cost of the
scheme.
u Bigger
sized pipes are to be laid because full day’s supply is to be provided within
few hours of supply.
u A
large number of valves and other fittings will have to be installed.
u During
non supply hours, consumers generally leave their taps open. This may cause
large wastages.
Conclusion:
Water distribution system is the life of a fish farming system. Managing a good irrigation system make a successful farmer.
