In a conversation with Earth.Org, Vishwanath Srikantaiah, a water conservation expert and urban planner, discussed the many initiatives that have been implemented to improve water security in Bangalore, India’s third most populous city. Interestingly, many of these initiatives can be mapped – intentionally or not – to circular economy principles.

By Sangeeta Jayadevan. Read part 1 here.

Water is vital to all forms of life. About 96.5% of the Earth’s water is in our oceans and is therefore too salty to drink. Freshwater makes up less than three percent of the Earth’s total water, with most of it locked away in glaciers, ice caps or very deep underground. Less than 1% of all water is accessible as freshwater.  

India is a water-stressed country, having 18% of the world’s population but only 4% of the world’s freshwater. Water stress is felt acutely in some of its large densely populated cities.  

Earth.Org interviewed Srikantaiah Vishwanath, a water conservation expert, well-known for his pioneering efforts to find solutions to the freshwater crisis. He teaches, writes and engages with water and sustainable water practices, which help cities become self-sufficient in water needs. Vishwanath’s model is being replicated in multiple cities across India.  

In this interview, Vishwanath discusses solutions for water security, with Bengaluru, India as a case-study. 

EO: Bengaluru is India’s third-largest city, with a population of over 14 million. The city has faced repeated water crises, exacerbated by irregular monsoons and weather patterns.  The demand for water is expected to increase as the city continues to grow. How will the city manage to provide water for all its people in the future? 

Vishwanath: Bengaluru’s main source of water is the river Kaveri located more than 100 kms away. Additionally, the city receives the equivalent of 3,000 million liters per day in terms of rainfall, which  along with water from river Kaveri is adequate for the city’s growth. The challenge is to harvest this 3,000 million liters and bring it into play for supplementing the water requirements of the city.   

In Bengaluru, it is mandatory for every residential unit to have its own rainwater harvesting system. So the city strives to engage every house as part of the solution through rainwater harvesting. At the next level, the city is looking at reviving lakes. The rainwater that runs off from roads, parks, and open spaces is directed towards the city’s lakes, allowing water levels to increase, thereby recharging underground aquifers. It is also planned for parks and open spaces to have their own rainwater harvesting systems through swales and recharge wells.  

So through prudent management of rainwater and engaging every citizen as part of the solution, the city strives to balance its water requirement, helping the city become self-sufficient in terms of demand and supply. This is the way that every city in India has to go and every city in the world has to go.

EO: But most large cities in India are like concrete jungles with minimal open areas where water can naturally see through. In this scenario, what can cities do to ensure that rainwater doesn’t just run off, but actually recharges groundwater?

Vishwanath : We have to treat rainwater as a productive resource. We have to understand that we are concreting the surface. Therefore we have to create percolation spaces, cracks or sponge cities as they are called in China to make sure that this water recharges the groundwater.

EO: Is the recharging of groundwater dependent only on rainfall? For context, recently, Bengaluru had no rain for six months at a stretch. How can groundwater levels be maintained? 

Vishwanath: We must understand the storage capacity of the underground aquifers to hold water. We have found that in many places in Bengaluru, the storage capacity is 20 times the surface water storage. So if you top up the aquifer during the rainy season, you can draw on it like a bank during dry spells. There is enough and more capacity in the aquifer to hold water. How do we top it up?

There are two ways to do it. One is through rainwater harvesting and recharging. The other is to use treated water to recharge the aquifers. We need to be smart about understanding aquifers and making sure that it becomes part of your solution.

EO: Could you elaborate further on reusing wastewater?

Vishwanath: Treated wastewater is a huge opportunity for any city.  About 80% of the water that we consume in our homes can potentially come back into the system as used water. The water we use in our dishwashers, washing machines  and showers is referred to as ‘grey’ water. It can be treated at source in apartments and at sewage treatment plants. We need to invest in sewage networks so that every drop of grey water is collected and treated. This treated water is then available for reuse.

So where will the reuse be?

It can directly be used in our homes for non-drinking purposes. It can be used in  industries which require ever-increasing quantities of water. Rivers, lakes, streams and wetlands can be supplied with treated wastewater. Finally, agriculture reuse. The hinterland of Bengaluru is drought prone and climate change prone. But our farmers are very proactive. The treated wastewater reaches them through lakes that exist in their surroundings. This helps farmers become water secure and in turn, helps Bengaluru city become food secure.

Bengaluru is running the second largest project of its kind, in the world, next only to Mexico City, to treat roughly around 2,000 million litres per day of wastewater and supply to farmers to fill 500 lakes and make sure that 64,000 farmers receive the treated wastewater. About 1.1 million hectares of land is brought under cultivation, so that the farmers are climate secure, water secure and the city is food secure. Thus wastewater is recycled and put to productive use.

EO: What does efficient urban water infrastructure look like?

Vishwanath: I’d like to draw on the experience of Singapore which talks about four taps and in the case of Bengaluru, there are six taps. 

The first is the pipe water from the river Kaveri which is about 100 kilometers away. Second is rain water which falls on our city. The third is surface water sources like lakes. The fourth is aquifers which hold water. The fifth is treated wastewater. The sixth is actually a tap control. It’s called demand management. This requires pricing water appropriately to ensure that people use water conservatively. This requires mandating water efficient fixtures on taps, flushes and showers. For example, Bengaluru has mandated the installation of flow restrictors or aerators for taps in all homes and commercial establishments. It also requires reducing leakage in water pipes.

By wisely using these six taps, we can strive to understand the demand on water and make sure that it’s balanced by the supply. Demand management is at the heart of how cities will manage water in the future.

EO: How can each one of us play a role in sustainable water management?

Vishwanath: For each one of us, the six taps are open for engagement. We can engage with rainwater through rainwater harvesting. We can engage with surface water by being part of communities who clean up lakes, streams and rivers. We can make sure that community and infrastructure is in play for harvesting the water. We can make sure that the piped water from our taps is not wasted. The wastewater that goes out from our house can be of better quality. We can use eco-friendly detergents. We can use good behavior in not pushing oil, paints and other chemicals into sinks and toilets.  We can plant trees which helps cool the city, reducing the demand for air conditioners, which is an indirect control on water. And finally, engaging with the state institutions to understand and improve their accountability and responsibility will be something that citizens need to do.

EO: How do we involve children in water management to make them more aware and more responsible? 

Vishwanath: Children are the future adults. Biome [the trust set-up by Vishwanath] works with public schools to engage children in water conservation activities. Children learn to appreciate rainfall patterns, learn to test for chemicals in the water using water quality testing kits, and learn about rainwater harvesting. 

Once children are sensitized to rain and to water quality and to the basics needed in the community, they are one of the best ambassadors in persuading their parents to shut off the tap to make sure the water is used efficiently and not wasted. Working with children is essential because water literacy is what society needs urgently.

EO: What are some common ideas to improve water security that apply to all cities? 

Vishwanath: The common ideas across cities is to protect your flood plains, protect your lakes, wetlands and rivers from illegal construction, pollution and debris. Make sure that local aquifers are treated respectfully. Make sure that pollution is reduced, if not eliminated, so that fresh water is not contaminated. Price water appropriately to reduce wastage. Implement rainwater harvesting. Treat water as a human right and make sure that everybody has access to water.

Interview with Vishwanath Srikantaiah on sustainable water management in India.

Featured image: Wikimedia Commons.