It is worth remembering that 11% of the total freshwater on earth is groundwater available up to a depth of 800m which can be extracted for use. India is one among the top 12 water-poor countries with the per capita availability of 1,850 m3/person/year as against the world average of 7,690 m3/person/year. An analysis based on the rainfall availability and demand-supply gap shows that even if 50% of the rainwater is harvested, it could help in bridging the demand-supply gap.
In a scheme initiated in 2002, financial assistance is being provided by the Delhi Government to RWAs, cooperative group housing societies, schools, hospitals, and NGOs to install RWH facilities. 50% of total cost of the RWH structure or Rs one lakh, whichever is less, is being provided as assistance. 206 cases have been approved for financial assistance out of which 162 cases have been provided financial assistance, says a DJB spokesperson.
The most recent initiative to promote rainwater harvesting includes the directions by CGWA to all residential group housing societies, institutions, schools, hotels and industrial establishments falling in the over-exploited and critical areas to adopt roof-top rain water harvesting system.
Despite the notifications from various governments, roof top rainwater harvesting is yet to catch-up, primarily due to poor implementation. The CGWA notification deadline ended in May this year. But officials believe that not all have complied to this directive. We have issued similar notifications a few months back as well. However, I dont think many have complied with the directive, says Sushil Gupta, Regional Director, CGWA. Gupta believes people should adopt such measures simply because there is a need. Rainwater harvesting (RWH) is the need of the hour and will prove beneficial in the long run, Gupta informs. However, lack of any penalty for non-compliance acts against the good intentions of the measure. Roof-top rainwater harvesting is just the beginning. Much more needs to be done, says Professor Suresh Rohilla of the Centre for Science and Environment (CSE).
This directive is just one of the many that have come in the past. One such directive came in 2001 by Ministry of Urban Development and Poverty Alleviation. It made rainwater harvesting mandatory in all the new buildings in Delhi with a roof area of more than 100 m2 and in all plots with an area of more than 1,000 m2, that are being developed. Similarly, rainwater harvesting has been made mandatory in buildings with an area of 250 m2 or more in Indore; with an area of 1,000 m2 or more in Kanpur; with an area of 300 m2 or more Hyderabad and by the authorities in Tamil Nadu, Rajasthan, Gujarat and Mumbai. In Gurgaon and the adjoining industrial areas, all the institutions and residential colonies have been asked to adopt rain water harvesting. Water experts believe that in large scale rainwater harvesting implementation, enforcement of any applicable laws and regulations would be the critical factor. Several cities have statutes on their books regarding rainwater harvesting but these are not being publicised and enforced, hence the public is not doing anything about it. In Chennai, due to the acute shortage of fresh water, they have been enforcing the law to some extent and there is large-scale implementation of RWH structures, says Vijay Krishna, director, India Water Portal.
Take the case of Mumbai. Since 2002, it has been mandatory for new buildings to install rainwater-harvesting facilities. However, until 2007, only 185 buildings had such facilities installed. The figure was 444 in May 2008, and 900 in May 2009. At present only 1,651 buildings in Mumbai have rainwater harvesting facilities installed, which means just about 750 buildings made provisions for rainwater harvesting in last year. Also, completion certificates for buildings cannot be given without rainwater harvesting structures, yet the practice was ignored and FICCI statistics reveal that 828 buildings do not have rainwater-harvesting installations. Experts observe that this is because civic authorities lack a system to monitor the implementation.
If implemented successfully, rainwater-harvesting installations can prop up water tables in urban areas. However, results may vary as hydrological opportunities for roof water harvesting depend on per capita roof area and rainfall. According to a study Roof Water harvesting for Domestic Water Security: Who gains and who loses published in 2004, rooftop water harvesting has extremely poor scope in LIG, MIG housing stocks, especially in low rainfall years. Citing the example of Ahmedabad, the study reveals:
* Rainfall once in six years: high:1,060 mm; low:316 mm
* For LIG living in three-storey apartments, water is sufficient for five days in a bad year; in a good rainfall year, it will be sufficient for 16 days
* For MIG in multi-storey apartments, water would be sufficient for one week in a bad year to 23 days in a good year
* For HIG, in small bungalows, water is sufficient for 29 days in bad year, 99 days in good year
* For HIGs in multi-storeyed apartments, water would be sufficient for 17 days in a good year to five days in a bad year
Bangalore has become the latest city to make roof top rainwater harvesting mandatory. S Vishwanath, a Bangalore based rain water harvesting expert, believes that this move could fulfill 25% to 40% of the citys water needs. However, lessons need to be learnt from Bangalore as well. The deadline for implementation has been indefinitely postponed from May 27. There is a lot of RWH construction activity going on now, but still far less than what one would expect if all the establishments covered under the regulation were making efforts to implement RWH. Also, there seems to be a massive under capacity of trained plumbers, masons etc to design and implement RWH structures, says Krishna.
Simply formulating laws doesnt help. The right ecosystem is also required to facilitate the laws to work. Krishna also advocates that RWH, (when used to recharge the groundwater), will have the best effect when it is done based on understanding of the geology and groundwater of a particular area. This is too much to expect of citizens or plumbers, so the government has to step in again and come up with guidelines for optimum implementation. CGWA, which has strong scientific and technical manpower, can be best utilised in this direction, says Krishna. What is also required is a coordinated effort. Mumbai has most of the population staying in co-operative housing societies. However, only those societies which have aware, active members who are united in thought and action are able to implement RWH, says Mumbai-based RWH expert Dr Ajit Gokhale. He also cites the need for reviving the traditional methods of rainwater harvesting like making and maintaining ponds and lakes, as there are no specific global models to follow. The monsoon is not a global phenomena. Hence, India should not adopt any model, but should evolve its own model based on its seasonal rainfall and need for low operating costs, says Gokhale.
With directives and measures in place, what is required is adequate number of trained resources to carry forward the good work. With cost of setting up a RWH plant ranging from a few thousands to a couple of lakhs, depending upon the size of the population, the effort is a one time investment with life long benefits.