Water Conservation in Sustainable Urban Development
- Dr. S. V. Ranade
Due to rapid growth of urbanization, there is unprecedented demand for new residential constructions. As a result, old houses, vacant plots, open spaces in the urban area are getting replaced by large building complexes and multistoried buildings. Increase in population density due to these new buildings creates necessity of facility centres and demand for low income servant community. This community cannot afford to stay far away from work place and prefer to live in temporary huts nearby. This leads to growth of unauthorized slum areas.
Water is a basic need of human being. In urban planning, water resource management assumes special importance as the availability of water and infrastructural facilities for protected water supply have to meet the ever increasing demand of water. The existing water supply and under drainage systems fall short of new enhanced requirements. As a result, there is shortage of water supply in some areas whereas excess wastewater in unsewered area.
Water Conservation Plan
Under this scenario, effective water conservation and environmental protection in urban planning would need a three- pronged approach ie at individual household level, community level and as a city service project .
Water Conservation at Individual Household level
Rain water harvesting, water conservation by reducing use and wastage of water and recycling of wastewater for non potable purposes by individual households can have great impact on reducing the magnitude of the problem.
Rainwater is purest form of natural water source and should be harvested and used for potable purposes by storing it after simple filtration and disinfection techniques. The excess rainwater should be used for recharging groundwater.
Water consumption can be minimized if we use it carefully and prevent its wastage. Water saving plumbing fixtures and sensor based taps can reduce water requirement considerably, however, the cost of such gadgets are high and hence their use in individual houses is rare. Same is the case with recycling of wastewater. In general the method of wastewater disposal is septic tank followed by soakage pit and so called low cost methods of treatment are not considered due to cost or space requirement in individual houses.
Effective implementation of water conservation measures depends heavily on public awareness and education coupled with legal controls and incentive schemes for water related taxes.
Water Conservation at Community Level
In case of large building complexes, hospitals, hotels and business places, it is necessary to develop appropriate reward or punishment system for effective water conservation.
Segregation & treatment of greywater and soil waste provides effective and economical method of wastewater recycling. At Walchand Institute of Technology, Solapur such system is successfully implemented. The soil wastes from hostels are separately treated in small digestors the supernatant from digestors is treated with grey water ( from wash basins, bath and kitchen) in anerobic filter. The treated wastewater was used for gardening reducing total water requirement.
In the city extension area, the housing colonies have to keep some area vacant for public purpose. City authorities can enforce the societies to use portion of this vacant land for wastewater reuse by employing DEWATS and composting of solid wastes. Legal enforcement of rain water harvesting, using water saving fixtures like dual flush for closets, sensor based wash basins, aerated flow shower heads, waterless urinals and constructing low cost wastewater treatment and recycling is possible for new establishments. Green rating as suggested by CII GRIHA star rating system may help in this case. Reduction in property tax and water related taxes as an incentive may also give impetus to effective water conservation.
Direct pipeline for potable water
In order to supply unpolluted water to urban areas, direct pipeline from dam storage is considered as better alternative than lifting the water from river. However, it is a long term project and the cost of such scheme may become limiting factor. It is argued that such a system will reduce importance of water quality preservation in river and would affect rural population who have to depend on river water.
Dual reticulation system
Dual reticulation system as used widely in Australia is based on the principle of providing separate pipe networks for potable water and water for other non-potable uses. Such systems are high capital intensive but prevent wastage of well treated potable quality water for non potable purposes.
24x7 water supply
24x7 continuous water supply system can eliminate necessity of water storage for each house, will prevent entry of contaminated water due to positive pressure and would reduce the cost of water distribution network. The success of this system depends on leakproof distribution and strict water metering system.
Present status of Water Treatment Plants
Design and operation of water treatment plants in India have remained traditional with use of conventional treatment units and operation by untrained personnel. Most of the plants are quite old and have not been augmented due to lack of funds. Over the years, the demand of water has increased significantly, but the plants are being operated under overloaded condition resulting in unsatisfactory performance. A fact-finding survey by NEERI1 revealed deteriorated conditions of water treatment plants in India during 1972 and the conditions have remained practically the same till now. Poor pre-treatment and non-availability of skilled personnel for operating the plant make the situation worse, resulting in large and unpredictable changes in treated water quality.
The existing water treatment plants can be upgraded by incorporating new technologies like, tube settlers, multi-media filtration and electronic monitoring and control equipment. In this process major infrastructural construction cost can be saved. However, it is seen that, there is a tendency to scrap old plants and erect new plants. Research and development work done in India for augmentation of existing plants is not put into practice resulting in financial loss and making the research effort a futile exercise.
Impact of Enhanced Water Supply on Wastewater Collection System
It is observed that water supply enhancement projects are sanctioned and implemented on priority. Such increase in water supply leads to increase in wastewater flow which cannot be effectively collected by existing city sewerage system leading to pollution of natural drains (Nallahs) and storm water gutters. Due to blockage by debris or due to unavailability of proper slope, these gutters are often full with stagnant water creating health hazard and mosquito breeding. In fact water supply and drainage projects must be implemented simultaneously to avoid pollution due to excess wastewater generation.
Vacant plots, public open areas are often used for dumping solid wastes by neighboring community. If there is stagnant water in such areas, it also creates unattended pollution spots. Even though, there is door to door garbage collection system and provision of public dustbins, the solid wastes lying in open spaces and pools of stagnant polluted water remain unattended.
Provision of proper under drainage system can give lasting solution to this problem but augmentation of existing drainage schemes or design of new systems require large financial outlay and long time span for completion. It is seen that in majority of cases, such schemes are stuck due to financial constraints and low priority than water supply schemes. Hence sustainability of environmental quality in growing urban area cannot be maintained within safe limits.
Under these circumstances, only option is to provide effective short term measures to Short Term Measures to avoid environmental pollution.
a) It is essential to provide efficient sewage lifting system for reducing pollution due to stagnant wastewater in open gutters and public places. Sewage carrying tankers with vehicle mounted small capacity slurry pumps can be used to pump such stagnant sullage water and discharge it in nearby manhole of existing under drainage system atleast twice in a week. This will prevent mosquito breeding and reduce ground water pollution significantly.
b) Provision of modified root zone cum percolating gravel beds along both the edges of existing natural drains will partially treat incoming wastewater from unsewered area and prevent entry of floating solids and garbage in nalla. This will help in keeping the natural drains clean and under flowing condition.
Dnyandeep Foundation Initiatives
Internet is the modern, effective yet very economical communication medium for educating masses, providing latest technology information with multimedia content, get feedback and video conferencing of all decision makers and stake holders concerning the project life cycle. Dnyandeep Foundation has launched two websites ie www.envis.org and www.green-tech.biz for creating awareness and education regarding Environmental and Green Technology.
Now the foundation has planned to develop environmental resource group and impart online education courses in these fields. There shall be online discussion forum to promote communication between architects, engineers and building professionals interested in environmentally responsible design and construction.
Let us hope that we shall be able to build strong active group of resource personnel for education and planning of sustainable urban development projects.