Literature Review
2.1. WATER SUPPLY SYSTEM: AN OVERVIEW:
Any research work calls for an understanding of the fundamentals of the field of study. The area of study being the ‘water supply system’, attempts have been made: firstly, to understand the basic issues related to water supply system. Secondly, with this basic understanding the water supply systems of various cities both in India and abroad countries have been studied to get acquainted with the various approaches in dealing with the varied problems related to water supply system. Thirdly, the various techniques and management systems have been analytically reviewed.
2.1.1. SYSTEMS OF WATER SUPPLY:
Continuous System (24 hours of day)
- Considerable wastage of water if there are no meters
Intermittent System (Fixed hours of day)
- Size of pipes required may be greater
- Pollution of stored water
- Adapted where less quantity of water is available
- Easy to carry out the repairs
2.1.2. DISTRIBUTION SYSTEMS OF WATER SUPPLY:
Gravity System
- Economical
- Pipes suffer less wear & tear
- Source of supply has to be situated at higher level than distribution areas
Gravity & Pumping System
- Economical
- Pipes suffer less wear & tear
- Higher pressure can be developed for Fire demands
Pumping System
- Costlier
- Power failure disturbs the distribution
- Constant attendance is required
2.1.3. LAYOUT OF DISTRIBUTION PIPES:
The various layouts and their advantages and disadvantages are discussed below,
Table 2.1. Various Pipe Network Layouts And Their Advantages & Disadvantages.
| Layout |
Advantages |
Disadvantages |
| Dead end Method |
- Discharge & pressure can be worked out accurately
- Cutoff valves are less
- Laying of water pipes is simple
|
- During repairs, large portion of distribution area is affected
- At dead ends there is no free circulation of water
|
| Grid iron Method |
- In case of repairs, small portion of distribution will be affected
- Free circulation of water
- Plenty of water is available for the fighting purpose
|
- Costlier
- Larger lengths of pipes
- More number of Valves
|
| Radial Method |
- Quick service
- Calculations are simple
|
- Suitable for Radial streets
|
| Circular Method |
- In case of repairs, small portion of distribution will be affected
- Free circulation of water
- Plenty of water is available for the fighting purpose
|
- Costlier
- Larger lengths of pipes
- More number of Valves
|
2.1.4. COMPONENTS OF COSTS IN WATER PROVISION:
- The repayment of capital loans and interest charges,
- Operations and maintenance expenditure. This includes the following
- Pumping of water from the sources
- Treatment of water, (form only a small proportion of the total cost).
- Transmission and distribution costs to users,
- A larger expenditure on electricity
- The higher the density of population, the lower is the per capita cost.
- An uneven and irregular terrain increases the pumping costs and also requires a larger network of pipes.
- Accounting and billing expenses, and
- Administration and general expenses.
2.1.5. COSTS TO BE COVERED BY WATER INCOMES:
- Incomes from the sale of water are expected to cover all operating costs,
- Operating costs + portion of the capital expenditure which is needed for replacement and renewals, and tf``
- A small amount towards creating fresh capital assets for meeting the future requirements of water.
2.1.6. CHARGING OF WATER:
There are three methods of charging for water, in technical terms, are referred to as charging vehicles. These are –
- As a percentage of ratable value
- It is an indirect method of charging for water, and involves a water tax on the annual value of the premises calculated on the basis of gross annual value or rent.
- This system is based on the ‘ability to pay’.
- Charges based on meter reading
- This is a scientific method of charging for water
- Chance of fraudulent practices.
- It does not take into account the ability to pay.
- Other methods and systems
- Ferrule rating, simplifies the accounting procedures.
- No control on the amount of water consumed.
2.1.7. EXPENDITURE-INCOME GAP:
In spite of collecting charges by the above-mentioned methods, still there is a huge gap in expenditure-income. This is mainly due to the following,
- Un-metered supplies
- Public stand posts
Therefore, the municipal bodies are expected to cover these costs through a system of cross subsidization.
2.2. APPROPRIATE TECHNOLOGY:
The endeavor for selecting an appropriate technology should be to optimize the total cost of the system. Also, water is treated as a scarce resource.
2.2.1. WATER CONSERVATION:
- Leak detection and preventive maintenance:
- Water losses are accounted to 20 - 40 percent of the total flow in the system.
- External pollution may get into the system during the non-supply hours through points of leak.
- Water conservation at the household level:
- The wasteful consumption of water by households can be reduced by metering of water use or by charging economic prices for water.
- Appropriate technologies need to be developed to minimize water use. For example, about 10 liters of water used for flushing toilets can be reduced to 3 – 4 liters by adopting low volume cisterns.
- Reuse and recycling of water:
Two distinct advantages –
- Reduction of pollution in the receiving water bodies.
- Reduction in the requirement of fresh water for various uses.
- In case of some of the multi-storied buildings, sewage is treated in the base basement and reused for the building’s air-conditioning system.
Case studies
- A couple of major industries around Chennai and Mumbai have been using treated sewage for various non-potable purposes.
- In Chandigarh, about 45 Mld of sewage is given tertiary treatment and then used for horticulture, watering of lawns, etc.
2.3.2. RAIN WATER HARVESTING :
Methods of artificial recharge in urban areas:
- Roof top water collection and recharge
- Storm run off collection and recharge
- Diversion of run off into existing surface water bodies
- Diversion of treated sewerage to recharge pits
A Case Study in Rajasthan, India
The successfulness of the technique has been illustrated with an Indian case study,
| Name of the Village | - Rajasmathiala a village in Saurashtra |
| Location | - 22 kms from district Rajkot |
| Population | - 1500 |
| Annual Rainfall | - 4 inches (normal 20 inches) |
| Total Investment | - 45 check dams, 13 percolation wells |
| Action committee | - The Gram Panchayat |
Situations before the project
- Waiting long hours in queues
- Women trudge miles for water
Situations after the project
- Abundant water in bores and wells (available at 15-20 feet).
- Supplies water to neighbouring drought-dogged villages
- By building the Check dams, whatever rain the village received is injected into the ground.
- They supply water daily to all houses with connections.
Source: The Indian Express, April 29, 2000
2.3.3. "SOFT PATH" APPROACH:
The "soft path" approach to water management involves a very different approach to water-related infrastructure.
It focuses,
- Water users can dramatically reduce water waste as a cost-effective alternative to new infrastructure.
- Soil and vegetation have tremendous capacities to absorb and retain storm water and filter the pollutants it contains. Techniques to take advantage of this capacity, even in very urban environments.
- The soft path emphasizes integration of techniques and systems across the four major water management sectors: water supply, end use, wastewater treatment, and storm water management.
- The soft path gives considerable attention to other benefits its methods can provide (such as energy savings from increased water efficiency, or property value improvements from micro-scale, landscape-based storm water measures).
2.3.4. SCADA (Supervisory Control and Data Acquisition):
- A basic SCADA system consists of a central computer that communicates with water system control points such as pumps, reservoirs, and metering stations. At these control points, remote terminal units gather and manage data. Water distribution systems may have hundreds of such control points, presenting a complex challenge in energy optimization.
- The SCADA system communicates with microchip-based "intelligent" terminals at place, schedules itself, and knows how to respond.
- SCADA systems can also warn of early mechanical problems and avoid costly breakdowns.
- SCADA systems can reduce the use and cost of water quality-related chemicals and even the number of employees needed to manage the system.
- Another noteworthy benefit is that SCADA systems can help discover and locate system leaks.
Case Study: Fresno in California
| Completed in the year | - 1988 |
| Cost of the project | - $3.2 million |
| Present power bills | - $ 50,00,000 / year |
| Earlier power bills | - $ 57,25,000 / year |
2.4. GENERAL STRUCTURE OF THE SYSTEM:
Generally, the system is maintained and operated by the Public Agencies. There are two major components in the provision of water supply,
- Tapping and transporting water from water resources,
- Treatment, storage and distribution of water
Conventionally, the system is controlled by the public agencies in the Indian context . The various stages of water supply scheme have been outlined .
2.5. CONCLUSIONS:
The review of above techniques and approaches in various cities both Indian and abroad countries have shown an inclination towards new technologies and privatization of the system. Some of the techniques and approaches are not innovative in nature, but a modification of the existing technique. However some techniques, which have shown signs of great success, have been examined to explore their applicability in Indian context, specifically to Hyderabad city.