Flow chart to quench Mumbai’s thirst

Mumbai is already feeling the heat and it has nothing to do with the mercury soaring in October. It’s the challenge of water scarcity that the city’s minders are bracing to face.

The city is heavily dependent on rains to meet its water needs. While it receives water from seven lakes, their catchment areas received nearly 10 per cent less rainfall this year.

Inadequate rainfall only compounds the problems for the Brihanmumbai Municipal Corporation that is perennially at war to keep the taps in the city flowing.

Of its requirement of 4,500 million litres a day (MLD), Mumbai gets 3,800 MLD – that’s a shortfall of 15 per cent. This apart, pilferage and leakage due to damaged pipelines suck out the city’s daily stock by a whopping 25 per cent.

The BMC claims it supplies 135 litres per person, as per international standards, to buildings and 45 litres per person to slums. However, the claims are always contested. Residents of Fort, Colaba and Churchgate recently marched to BMC’s A-Ward office of the civic body, complaining irregular water supply.

Officials said the corporation plans to build three more dams in the next 25 years to meet Mumbai’s ever-rising water demands. A water recycling plant is also being developed, they added.

However, the BMC has a lot to catch up on the water front, according to the public. It is grossly lacking in its rainwater harvesting efforts. The civic body has no data of housing complexes with rainwater harvesting system, say activists.

It’s only a handful of self-motivated initiatives that stand as shining examples. For instance, Chandrakant Khaire of Chintamani Building on Mithagar Road in Mulund said, their society installed a rainwater harvesting system in 2004. “Our well is charged throughout the year and we save at least 25 percent of civic water.”

Experts say conservation and augmentation efforts can help the city meet its shortfall with the available resources. DNA delves deep into five such areas.

Checking theft, wastage a must

The BMC can tide over its water woes to a large extent if it checks pilferage, and wastage during transportation, say experts.  

Of the seven lakes that supply water to Mumbai, two are within the city limits. The rest are located at a distance between 100 and 175 km.

Water from the sources is brought to the filtration plants in the city – Bhandup and Panjarpur near Bhiwandi – through huge pipes and water tunnels. The treated water is then distributed to 27 service reservoirs across Mumbai before it reaches households through a maze of pipes of varying sizes.

But major losses don’t occur during the long journey to the filtration plants. The target is potable water, within the city. The leakage happens through theft and damaged pipelines. “Nearly a quarter of the stock vanishes this way,” a civic official told DNA.

Also, most of the pipelines were laid three to four decades ago and many have rusted over the years, said officials, stressing the need for repairs and regular upkeep.

Officials said nearly 70 per cent of the pipeline network has been replaced with new tubes and work on underground pipes is still underway. More water tunnels that run much deeper under the ground are also being built, they said.

“Even if the water losses come down by 15 percent, citizens will get more water. Despite complaints, the BMC is reluctant to take action which is worrying,” said Crompton Texeira, who has been bringing to notice is voluntarily detecting water leakage for the last 15 years.

BMC officials said curb in leakage will also reduce water contamination. But they said the extensive network of pipelines in the city poses a huge challenge for them to track illegal tapping.

Dwarkanath Sanzgiri, former chief engineer of BMC’s water supply projects section said losses during supply is something that many countries face. “But it’s a bit high in Mumbai.” 

BMC lagging in tapping rainwater

In 2009, when Maharashtra faced one of the most severe droughts in the century, there were lots of discussion on conservation of water. The crisis had prompted the BMC to start vigorous campaigns on rainwater harvesting. The momentum has been lost in past nine years and the narrative has shifted to big dams.

The BMC had in 2012 made it mandatory for all new constructions above 1,000 square metres to set up a rainwater harvesting system. Later, it said construction sites spread over 300 square meters must install a system to tap rainwater to get the occupation certificate (OC). 

Despite the measures and making a provision for rainwater harvesting systems in the Development Plan 2034 – a blueprint for Mumbai, the BMC has no data on this. 

Experts put the blame on lack of administrative willpower for the poor progress on rainwater harvesting. “The civic body just issued a directive. They don’t have any guidelines on it. They don’t specify the capacity of the plant as per area of a building, fine for non-compliance,” said UM Paranjpe, trustee of Jalvardhini Pratishthan that offers guidance on rainwater harvesting across Maharashtra. Lack of guidelines means no violator can be dragged to court. 

“We have to take every measure to reduce the use of potable water and save it. Recycling is one aspect, rainwater harvesting is another,” he added. 

Mumbai receives over 2,457 mm of rains every year. If properly tapped through the existing wells, the city get nearly 589 million litres a day throughout the year. There are 16,867 wells across the city. 

With no clear policy for wells, the water bodies are being misused by the water mafia. 

The BMC had asked a groundwater survey and development agency to prepare a report on wells in Mumbai two years ago. But the project never took off, said sources.

Recycling is the way forward

Transporting water to the city is a costly affair, say experts. Of the 140 litres that BMC supplies for each person, very little is used for drinking and food. A major amount ends up in the sewerage and reaches the sea. An estimated 2,600 million litres of water is flushed out, which also pollutes the sea.

Mumbai has seven sewage treatment plants. However, they partially treat wastewater before disposing of in the sea. The project to upgrade them for tertiary treatment (so water can be used for gardening and industries) is delayed for almost 10 years. In between, BMC has started few pilot projects. It is supplying recycled water from Banganga plant at the rate of Rs 12 per kilo-litre to Willingdon Golf Club. 

Love grove pumping station (3MLD), Banganga pumping station (1.5 MLD), Dadar pumping station (0.3 MLD) and Charkop sewage treatment plant (6MLD) are currently operational in the city.  However, they are a drop in the ocean compared to the huge requirement of 2,600 MLD. 

A senior civic official said, “While work on the plant at Colaba has already begun, there were environment related issues with the Malad wastewater treatment plant. We are hoping to start work soon.” 

While the cost of this entire project is Rs 14,368 crore, all the plants together can treat 1700 - 1800 million litres of water a day. As per the BMC’s plan, work on all water treatment facilities is expected to be completed by 2025.

Desalination dream derailed

High cost and an energy-intensive process forced the BMC to put on hold its ambitious plan to set up a desalination plant for an estimated Rs 1,000 crore. The project was supposed to create 100 MLD potable water from seawater. 

Even in 2017, Chief Minister Devendra Fadnavis had in a written reply to state legislative council said that the project had been dropped due to concerns over costs and logistics.

According to a BMC official, the process is very costly and electricity-intensive. Investors did not come forward, he said. It depends on all-round supply of power. Such desalination projects are operational in cities like Dubai and Chennai. 

The project required at least 25 hectares of land and while the BMC did not have space of its own for it, the Mumbai Port Trust, which has a huge land bank on the eastern sea front, had declined to part with the land.

While desalinated water would cost citizens Rs 70 per 1,000 litres, the BMC supplies 1,000 litres of water to end-users for just Rs 4.50. The report said it would make more sense to invest in projects to bring water from outside the city.

VIEWS FROM ABROAD

Saudi Arabia

Saudi Arabia has long been a leader in desalination. It is believed that it’s the largest producer of desalinated water in the world. Most recently, it’s taken desalination technology to the next level by introducing desalination powered by renewable, solar energy – a resource that’s plentiful in this desert nation.

Israel

Israel is another country situated in desert location. But, at the same time, it is also known as a leader in water conservation technology. The country has more than 300 water technology companies specialising in desalination that export water to other countries. It also recycles country’s 85 percent of waste-water.

United states

In the US, California has been besieged by historic droughts, which have been the stimulus to setting up the largest desalination plant in the Western Hemisphere. It was started operating in 2016 and provide around 50 million gallons of seawater per day through a 10-mile water delivery pipeline.

Input by Prajakta Kasale and Amit Srivastava