Harvest rainwater to avert water crisis

Alarm bells are ringing. By 2020, 21 cities, including New Delhi, Bengaluru, Chennai and Hyderabad, will run out of groundwater, affecting nearly 100 million people, as per a report of the Niti Aayog. This is not just an urban crisis. Rural India is going to be even more affected. Water scarcity is already staring in our face, big time.

Presently, groundwater constitutes the largest share of the country’s agriculture and drinking water supply needs. About 89% of the groundwater is used for irrigation; 9% for household purposes and 2% for industrial needs. In all, groundwater resources meet nearly 50% of urban water requirements and 85% of rural needs as per the Central Ground Water Board. But groundwater resources are drying up rapidly, and there is urgent need to shore up these resources on a massive scale, if not we will be doomed. It is hoped that the newly constituted Jal Shakti Ministry will aggressively push for any solution, big or small, that will help us tide over the imminent water crisis.

One way it can be done, is through rainwater harvesting

The moment one hears ‘rainwater harvesting’, chances are high of dismissing it as ‘nothing new’ and that it is a system which has been tried and successfully tested on a smaller scale. That it can be done on larger scale is not known much. What the country desperately needs is an all-systems policy for optimal utilisation of river water, inter-linking of rivers, rainwater harvesting and tapping ocean water.

Rainwater harvesting has enormous potential. Irrespective of the vagaries of the monsoons, the country receives sufficient annual rainfall that could meet the needs of the 1.3 billion population. The Central Water Commission estimates that India requires a maximum of 3,000 billion cubic metres of water annually. In actuality, it receives about 4,000 billion cubic metres of rain.

The sad part is that almost all the rainwater goes waste or rather remains untapped — only 8% of the country's rainfall is harvested, among the lowest in the world. What is disturbing is the slow adoption rate of rainwater harvesting systems which involves simple techniques and is not at all ‘rocket science’. Rainwater harvesting is nothing but collection of rain in a scientific and controlled manner for future use and can be practiced by individual tenements to large complexes.

The Infosys example

The campuses of Infosys are an example of successful implementation of rainwater harvesting systems. Infosys has 410 ‘V’ wire injection wells, 25 lakes and engages in rooftop rainwater harvesting across its campuses. This resulted in an 8.33% reduction in per capita consumption of water in 2017 compared to the previous year. There are many such examples of tapping rainwater, answering the question as to whether rainwater harvesting can be deployed over larger areas.

In Chikmagalur, a project is underway by Farmland Rainwater Harvesting Systems to tap rainwater over an area of five acres. This is said to be one of the largest such experiments in the world, undertaken in a drought-hit area. Onsite, there are seven ‘V’ wire injection wells and rainwater is collected only through gravity. The groundwater table has risen considerably and is said to be already benefitting the neighbouring villages. The concept of water neutrality is introduced wherein there is total water recycling and zero waste. This large-scale experiment can be replicated anywhere, to any scale.

While such efforts are on here and there, what the state governments need to do, besides regulating sinking of borewells, is come out aggressively with a rainwater harvesting policy. The Karnataka government, apart from planning such a policy, should ensure effective implementation of ‘krishi honda’ (agricultural ponds) in villages.

Governments should incentivise rainwater harvesting. The Union government can take a step towards this by bringing down the Goods and Service Tax (GST) on rainwater harvesting systems from a high of 18% to zero-rate.

It is time to get the objectives of the National Water Mission in action. The laudable objectives include enhanced storage both above and below ground, rainwater harvesting, coupled with equitable and efficient management structures. It truly has to become a national mission.

(The writer is co-founder of Farmland Rainwater Harvesting Systems)