Tap the Rain: Rainwater harvesting benefits & challenges in India

New Delhi: 'Catch where it falls, when it falls'. Rainwater shouldn't be wasted, it needs to be tapped and used. Rainwater harvesting (RWH) assumes more importance than ever before as Indian cities are reeling under severe water crisis. RWH can bring about a relief from the raging crunch.

Water harvesting is the practice of capturing and storing rainwater for future use. In places where there are limited water resources, RWH could be very beneficial. RWH involves capturing rainwater from rooftops, paved areas, or open land. It is then stored and used later. The practice goes a long way in conserving water by reducing reliance on traditional water sources like rivers, lakes, or groundwater.

The rainwater collected in such a way can be utilised for different purposes such as irrigation, toilet flushing, landscaping, or even drinking water, after it undergoes proper filtration and treatment.

RWH promotes the cause of sustainability, reduces water costs, and offers a dependable water source, making it an environmentally friendly solution. Projections suggest that the rainwater harvesting system market could reach US$ 1,146.8 million by 2028, growing at a compound annual growth rate (CAGR) of 3.8% from 2021.

According to some studies, a well-designed rainwater harvesting system can reduce a household's annual water consumption by up to 50%. In urban places, it has the potential to meet up to 30% of the water demand. A 1,000 square meter rooftop can harvest up to 500,000 liters of rainwater every year in areas where there is average rainfall.

Some time back, the Central Ground Water Board (CGWB) of India estimated that rainwater harvesting can help recharge over 1 million aquifers across the country.

In many Indian cities, RWH in buildings had been made mandatory to help reduce water shortages, recharge groundwater levels, and promote sustainable water management. Chennai was the first city in India to make rainwater harvesting mandatory. Since 2003, rainwater harvesting is compulsory for all new buildings in Tamil Nadu. Bengaluru made rainwater harvesting mandatory in 2009 for buildings with plot sizes above 60 square meters.

In 2002, the Delhi government made rainwater harvesting mandatory for all new buildings, as well as for existing buildings with plots larger than 100 square meters. In 2005, the Hyderabad Metropolitan Development Authority (HMDA) took a similar step. In 2007, Pune implemented rainwater harvesting rules for new buildings. Mumbai's civic body -- Brihanmumbai Municipal Corporation (BMC) -- also made rainwater harvesting mandatory for buildings with more than 300 square meters of plot area in 2009.

However, most of the rules and regulations have remained only on paper. Many residential as well as commercial buildings still don't have RWH system installed. Even the new constructions don't have it. Only around 3000 societies of the total estimated 20,000 societies in Mumbai reportedly had RWH between 2007 and 2021.

The biggest impediment and challenge in implementation of RWH is public awareness, which is quite low. A majority of people and property developers are not aware about the advantages or technical requirements of rainwater harvesting systems. Despite the rules, in some cities the civic body officials fail to keep a tab on enforcement and compliance  because the resources are inadequate. In many cases, the infrastructure to collect, store and distribute the harvested rainwater is also not good enough. A majority of house owners and builders find the installation and maintenance of RWH too costly, and so, they skirt the rule. They look for immediate returns, and fail to take into account the long-term benefits of these systems.

The challenges are immense. It all has to start with raising the awareness of the masses and sensitise them about the importance of RWH to mitigate the water woes. Civic bodies must be given more teeth and funds to ensure that the rules are implemented and the infrastructure is in place. It should give incentives like property tax rebate for RWH systems. The Occupation Certificate (OC) should only be issued after the functionality of RWH structure is fully checked. The cost of RWH also has to be brought down. While digging borewells has to be banned, percolation pits need to be dug in gardens and parks.

Corporate Social Responsibility (CSR) initiatives of companies should help in installation of rainwater harvesting systems in schools, hospitals, and community centers.

Recognising the crucial importance of rainwater harvesting, the Indian government has rolled out a slew of initiatives to promote its large-scale adoption across the country.

In 2021, the Ministry of Jal Shakti (MoJS) launched the Jal Shakti Abhiyan (JSA), an ambitious campaign designed to engage citizens in a nationwide initiative to combat water scarcity through a series of focused interventions. There were 5 key interventions of the scheme including water conservation and rainwater harvesting, renovation of traditional and other water bodies/tanks, reuse and recharge of bore wells, watershed development and intensive afforestation.

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The Smart Cities Mission, a key initiative of the Indian government, has also incorporated rainwater harvesting into its urban development plan. The National Water Mission is another government initiative that focuses on the efficient management of water resources and encourages rainwater harvesting. Integrated Watershed Management Programme is also aimed at enhancing water conservation and promote sustainable water management practices in rural areas, including rainwater harvesting.

Bengaluru Water Supply and Sewerage Board (BWSSB) is also launching a community rainwater harvesting programme. The first phase of the scheme is aimed at targeting areas within apartment complexes that had not been covered by previous rainwater harvesting systems. The community-based RWH systems will channel the collected rainwater to nearby lakes, contributing to the recharge of groundwater levels in the area. In Madhya Pradesh and Maharashtra, the state governments are encouraging the installation of rainwater harvesting systems in both urban and rural areas through a number of schemes.