Published By: Sayan Paul

Bengaluru On The Brink Of "Zero Water Days"? Exploring Rainwater Harvesting As A Solution To The Crisis

Rapid urbanization and all - but at what cost? Bengaluru's water crisis stands as an example of unsustainable development.

Bengaluru, the capital city of Karnataka, has seen rapid development, and consequently unprecedented economic growth, over the years. But everything comes with a cost; and for Bengaluru, that cost is evident in the form of environmental damage. Precisely, for quite some time now, the "Silicon Valley of India" has been grappling with a severe water crisis. This summer, there was a shortage of 300-500 million liters of water every day (the Cauvery and groundwater resources went dry), wreaking havoc on its millions of residents.

According to experts, the worst is yet to come, and Bengaluru is heading towards "zero water days". DH. Prafulla Saligram, secretary of the Society for Community Health Awareness Research and Action (SOCHARA), explained in a report, "We had around 400 lakes dating back 200 to 300 years ago. Due to unchecked growth, most of these have disappeared, and our dependence on external water sources has skyrocketed." On the other hand, an analysis by scientists of Indian Institute of Sciences states that the city has lost more than 60 percent of its green cover in the past few decades.

(Credit: Karnataka Weather)

Well, Bengaluru needs an estimated 2,600 MLD (million liters per day) of water for both drinking and industrial purposes. And the government has taken some measures to tackle the crisis. The Cauvery Phase V project is all set to be launched, which is one of the largest water supply initiatives in India. However, as far as long-term relief is concerned, experts believe rainwater harvesting could be the best solution.

What Is Rainwater Harvesting?

Simply put, rainwater harvesting refers to the process of collecting and storing rainwater and then using it for everything from domestic to industrial work.

The rainwater is collected from surfaces like rooftops, roads, and open grounds, and is then redirected to a reservoir. It has been used in several countries worldwide for thousands of years. In recent times, it has emerged as a popular practice in regions with water scarcity. It not only provides water when required but can also help manage flooding in low-lying areas.

(Credit: The Better India)

Rainwater Harvesting In Bengaluru - A Solution To Water Crisis

Scientists and engineers at the Karnataka State Council for Science and Technology along with other institutions have long been studying the potential of rainwater harvesting to tackle Bengaluru's water crisis. Back in 2009, Bangalore Water Supply and Sewerage Board (BWSSB) made rainwater harvesting mandatory in the city, issuing a guideline that "new residences with 30x40-foot sites must either recharge the groundwater table by harvesting rainwater or store it in a sump or tank". The Bengaluru Water Supply and Sewerage (Amendment) Act, 2021 extended this to 60x40 feet.

(Credit: The Art of Living)

Recently, considering the growing water crisis in the city, BWSSB has launched an initiative to do rainwater harvesting at a community level. The systems are being installed at private buildings, housing societies, roads, flyovers, and other areas. They identified 17 such apartments near the lakes (like Saul Kere Lake in Bellandur, Hoodi Lake, and Sheelavantha Kere Lake in Whitefield), and installed rainwater harvesting systems on the premises.

Experts believe that these may help in various ways. Firstly, it eases pressure on Bengaluru's traditional water sources, especially the Cauvery River. The water quality has improved, while the groundwater level is increasing gradually. On the other hand, it's effective at mitigating flooding (which is common in the city during monsoons) in low-lying areas.

It Can Meet Over 70% Of Bengaluru’s Water Requirements - T V Ramachandra

A few months ago, T V Ramachandra, coordinator, energy and wetland research group at the Indian Institute of Science (Bengaluru), said in a statement that rainwater harvesting can provide over 70% of Bengaluru's water requirements.

(Credit: Karthik Reddy)

He told the Deccan Herald, "Rainwater harvesting can, by itself, provide 15 TMC of water. Additionally, the city generates about 18 TMC of wastewater each year, of which we can obtain 16 TMC after treatment. This gives us a surplus to refill lakes and rejuvenate the groundwater table."