2. CONTENTS
Introduction: water supply
:Methodsof water supply
Continuous systemof water supply
Introduction
Working
Advantages & disadvantages
Intermittent systemof watersupply
Introduction
Working
Advantages & disadvantages
Comparison : continuous& intermittent system of watersupply
Discussion
3. WATER SUPPLY
WATER SUPPLY: is the provision of water by public
utilities, commercial organizations, community endeavors
or by individuals, usually via a system of pumps and
pipes. Irrigation is covered separately.
Or in another words it could be said as:
The process of self-provision or provision by third parties
in the water industry, commonly a public utility, of water
resources of various qualities to different users.
5. OBJECTIVE OF A WATER SERVICE
The fundamental objective of a water service is to
supply adequate and safe wholesome water
efficiently and effectively at an affordable price so
that the citizens are released from the hard
monotonous routine work of seeking their daily
water.
6. METHODS OF SUPPLYING WATER
The water can be supplied to the consumers by the
two systems:
1. Continuous system of water supply.
2. Intermittent system of water supply.
7. CONTINUOUS SYSTEM OF WATER
SUPPLY
24x7 supply is achieved when water is delivered
continuously to every consumer of the service 24
hours a day, every day of the year, through a
transmission and distribution system that is
continuously full and under positive pressure.
8. CONTINUOUS SYSTEM OF WATER
SUPPLY
Continuous supply systems are designed using the
following main parameters (EXPERT COMMITTEE
CONSTITUTED BY THE GOVERNMENT OF INDIA,
1999):
1. Flow of raw water
2. Water treatment plant
3. Water transmission system
Working
Operating of system components, pumps and
reservoirs, in the continuous supply systems is a result of
consumers needs: with reduced demand in the night
periods, pumps may operate at lower level and balancing
reservoirs may be refilled, whereas during the maximum
demand periods, the pumps will operate at their maximum
9. ADVANTAGES & DISADVANTAGES
ADVANTAGES:
In this system water is not stagnant in pipe at any
instant & hence fresh water is always available.
Lesser pipe sizes are required.
Fire hazards can be met within time.
DISADVANTAGES:
If there are some minor leakages etc in the system,
great volume of water is wasted because of long
duration of flow.
More water is required at the source which is difficult in
tropical countries like India, which get rains only during
a particular season.
More wastage of water due to lack of civic sense.
10. INTERMITTENT SYSTEM OF WATER
SUPPLY
Intermittent system: If plenty of water is not available,
the supply of water is divided into zones & each zone is
supplied with water for fixed hours in a day. As the water
is supplied after intervals, it is called intermittent system.
11. INTERMITTENT SYSTEM OF WATER
SUPPLY
Working
The working of the system is very simple. The distribution
area is divided into several zones & the timings of each
zone are so adjusted that good working pressure are
maintained in each zone.
Health Aspects
Consumers are advised to treat water coming from
intermittent water supply. As water becomes stagnant in
service reservoirs, bleaching powder is often used to
maintain a residual chlorine level.
12. ADVANTAGES
For older distribution systems having weaker joints and
more leakage, restrained supply hours can limit leakage
Reduced pressure also helps lowering leakage
Overall scarcity may sometimes be managed by
interrupting the water supply and equally balancing the
resources (controversial)
Time is available for repair and maintenance out of
supply hours
13. DISADVANTAGES
Systems do not operate as designed: components are
underused, others are overexploited and damaged
Inconvenience to consumers, mostly the poor (often, one
person per household is devoted to storing the water at
supply times)
Pipelines are subjected to vacuum condition after supply
hours, which can cause groundwater infiltration into the
pipelines with contamination of the supply or pipes
deformation
Frequent contamination requires household-level water
treatment, as well as higher doses of residual chlorine by the
supplier
Consumers need to store water between supplies and tend
to throw away remnant store. This causes water wastage and
storage costs
Frequent wear and tear on valves, water meters malfunction
More manpower and infrastructures needed
14. COMPARISON: CONTINUOUS &
INTERMITTENT SYSTEM OF WATER
SUPPLYPARAMETER CONTINUOUS
SYSTEM
INTERMITTENT SYSTEM
Fire demand Fire demand can be
met within time.
Fire demand cannot be met within
time; this may cause huge damage
before the supply could be turned on.
Domestic
storage
Storage is not
necessary, since there
is a continuous supply
of water 24X7.
The consumers have to store water for
non supply hours which is likely to get
contaminated. Some consumers may
not have sufficient storage tanks which
may lead to insanitary condition.
Size of pipes Comparatively lesser
diameter pipes are
used in continuous
system of water supply.
Bigger diameter pipes are required to
supply the water for the full day in a
very short period.
15. PARAMETER CONTINUOUS
SYSTEM
INTERMITTENT SYSTEM
Staff
requirement
Need not require much
manpower &
infrastructure.
More manpower and infrastructures
needed
Capital cost Low capital cost
compared to intermittent
system of water supply.
Higher capital cost.
Wastage of
water
There is considerable
wastage of water if
consumers do not
posses civic sense
regarding the
importance of treated
water.
The consumers leave their taps
open every time, & also if more
storage of water is done during non
supply periods. It is thrown off
causing wastage of water.
Contamination
problem
Both continuous and intermittent water distribution
systems might suffer from the contaminant intrusion
problem, and the intermittent systems were found more
vulnerable of contaminant intrusion.
16. DISCUSSION
Presently no Indian water utilities supplies 24X7 continuous
water supplies to their consumers (Journal of Indian works
association).
Intermittent water supply is one of the interference which gets in the
way of achieving the Millennium Development Goals in developing
countries. In India no city provides 24×7 continuous water supply to
their residents. There have been many endeavors to achieve this
most challenging task. But the high population density coupled with
unplanned distribution system and neglectfulness in water loss
management has been the reasons that are not allowing achieving
this important hallmark.
From intermittent to 24 x 7
Introducing equitable costs, reducing leakage and installing proper
storage can be the beginning of continuous water supply. Higher
tariffs are to be set for 24-hours supply zones, as long as they are
fully equipped with exact water meters, while the whole network’s
expansion is stopped. Little by little, 24-hours supply zones are to
be enlarged, and the number of connections too.
17. REFERENCES
Water supply & sanitary engineering by G. S. Birdie & J.
S. Birdie
Water supply & waste water engineering by B. S. N.
Raju
Manual on water supply & treatment
Internet sources