How Important is Rainwater Harvesting in Indian Cities

Every year as the summer sets in, water becomes scarce across the length and breadth of India. Can you imagine living in an Indian city and not having a water connection at your home? Well, a Bengaluru scientist has just done that.

By rainwater harvesting to meet all his family’s requirement of water at his home, Mr. A R Shivakumar, a senior scientist in Karnataka State Council for Science and Technology has not paid for water bill for 22 years. His family uses harvested rainwater for bathing, washing and even drinking.

How green is this building in Kerala! The 13-storey corporate office of V-Guard at Vennala is a green wonder. Every floor has a balcony with flowering plants surrounding it, which prevents the building from heating up. Only 10 percent of the building has an air-conditioning facility. All water requirements are met by rain-water harvesting and 2 open wells.

According to a 2015 report in The Hindu, the corporate office of V-Guard does not even have a corporation water connection!

There are many efforts such as these. For example, Mr. Subash Reddy, a self-taught engineer, is one of the few experts in Hyderabad striving to build site-specific and economical rainwater harvesting structures. Subash set up Smaran in 1997 to find and implement solutions for increasing water resources through rainwater harvesting.

As India has erratic rainfall in most years, a renewable water resource like rainwater, if properly harvested, can mitigate water scarcity to a huge extent.

How is Rain Water Harvesting Carried Out?

In India, rainwater harvesting has been in practice for more than 4000 years. It is basically a simple process of accumulating and storing of rainwater. Rainwater harvesting systems, since ancient times, has been applied as a supply for drinking water, water for irrigation, and water for livestock.

The systems are easy to construct from locally sourced inexpensive materials, and it has proved to be a success in most areas. The prime advantage of rainwater is that the quality of water is usually good, and it does not necessitate any treatment before consumption. Household rainfall catchments can significantly contribute where the source of drinking water is contaminated and scarce.

Ranging from fairly simple to extremely complicated industrial systems, there are a variety of techniques that can be used to harvest rainwater. Usually, rainwater is either harvested on a roof, or on the ground. The rate at which rainwater can be collected from either of the two systems is entirely dependent on the intensity of rainfall, the area of the systems in use, and its overall efficiency.

Rainwater Harvesting in Indian Cities

The history of rainwater harvesting and management can be traced back to Biblical times, and interestingly, this old technology has made a super comeback in a new way in a new world, promising to deliver a sustainable solution in eradicating the menace of a global water crisis.

Unfortunately, in the modern era, the age-old methodology of rainwater harvesting was greatly neglected. Years of negligence, and short-sighted water management policies that mostly rely on overexploitation of ground and river water, has once again brought rainwater harvesting to the fore because of its life-saving qualities.

Rainwater harvesting and management hold tremendous potential for alleviating storm-water runoff and reducing groundwater consumption, particularly in urban areas. Though the costs of installing modern rainwater harvesting systems, storing, and treatment of rainwater was an area of concern earlier, but now with the advent of new technologies, the investment has a positive return.

Today, rainwater harvesting systems are acting as incredible support systems in many Indian cities, providing a superb alternative to the main water supply, especially during dry seasons. Moreover, the advantages of storing rainwater are not only limited to a particular individual or a family, but it is coming off as a lifesaver for many urban communities as well.

Widespread installation of these systems is also revitalizing the natural properties of land, helping to improve the quality of groundwater, raising its level, and preventing wells and tube wells from drying up. Additionally, efficient deployment of rainwater harvesting systems is limiting surface runoff of water, which is reducing soil erosion, and increasing its fertility.

Common Methods of Urban Rainwater Harvesting

Some of the most familiar methodologies of urban rainwater harvesting and management are –

Surface Runoff Harvesting

Surface runoff harvesting is the most suitable method in urban clusters. Here, streams of surface runoff rainwater are redirected and stored for future use in specially-built reservoirs, either on the surface or underground. This provides a steady supply of clean, potable water, and also water for normal domestic uses.

Rooftop Rainwater Harvesting

Rooftop rainwater harvesting is the most popular of all harvesting options in urban areas. The system can be installed in an individual home environment, schools, colleges, and other institutional buildings that have more available roof space.

The underlying concept of rooftop rainwater harvesting is pretty simple and easily doable. A container needs to be constructed or placed beneath the roof level, which will store the rainwater intercepted and redirected towards it through pipes made out of wood, bamboo, or PVC. Though this is the basic concept, industrial-grade rooftop rainwater harvesting in big complexes is somewhat more complex.

Recharge Pits

Another common rainwater harvesting process is constructing recharge pits to hold the rainwater. Recharge pits can be of any size and shape, depending on the intensity of rainfall in a particular area. It is important to fill these recharge pits with coarse sand, boulders, and gravels, which act as natural filters that keep away dirt and impurities usually carried by the first flow of rainwater.

Rainwater Harvesting as State and Central Government Policy

More or less all states in India, through various legislative decisions, have made rainwater harvesting mandatory in government institutions, commercial complexes, and residential high-rises. Some of these laws have already come into effect, and others are soon to follow.

The Central Ministry for Drinking Water and Sanitation, in association with the Central Ground Water Board, and a battery of groundwater scientists and experts, has also prepared a conceptual document called the ‘Master Plan for Artificial Recharge to Ground Water in India’.

The master plan, related to rainwater harvesting and artificial recharge of groundwater, envisages the construction of about 23 lakh rainwater harvesting structures in rural areas, and close to 88 lakh artificial recharge and rainwater harvesting installations in urban centres.

Since natural resources like rainwater come free of cost, it seems like modern human beings forgot its valuable contribution, and the need to save it. Green living with new water-saving technologies and lifestyle is also catching on. In a world that is reeling under extreme water crisis, cities and communities across the globe will have to become more aware of rainwater harvesting, storing, and consciously using water.