It would be nearly enough water to supply the whole city if it actually reached people. But the aging system of pipes is leaking and corroded, is subject to illegal tapping, and simply doesn’t extend to nearly 20% of households. Around 40% of the water is lost.

The gap between what’s needed and what’s supplied is largely filled by hundreds of thousands of illegal, community-dug borewells around the city—and by what’s known as the “water mafia.” Depending on whom you ask, these are entrepreneurs filling the market void by tapping wells and delivering the resource in tankers to homes, apartment buildings, and businesses—or a cartel that sets exorbitant prices and occasionally resorts to strong-arm tactics to ensure demand.

What’s left of the Yamuna, after the Wasirabad has siphoned off most of its remaining water, runs through Delhi in a 22-kilometer stretch that is more of a sewage line than a river, the catchment for thousands of drainage basins that wind through the city, channeling the toxic runoff from homes, slums, businesses, and factories.

Saumya Khandelwal

Toxic sludge

On an early afternoon in late February, Gupta drives me to one of New Delhi’s drains near the sprawling, manicured grounds of the Sunder Nursery, a historic park in the center of the city. He weaves between concrete barriers and noses into a pull-off at the edge of an overpass.

There’s a sharp smell of sulfur in the air. Gupta steps out, walks up to a low wall, and points down into the Barapullah drain.

It’s a body of black muck that traces the curve of the overpass. A cluster of wire-haired boars root through trash that climbs the embankment, where they feed on sewage and garbage.

“And somebody’s going to slaughter and eat them,” Gupta says.

A healthy drainage basin would carry rainwater throughout the city, recharging aquifers and feeding the river. But slums without pipes and businesses without scruples dump sewage, garbage, and chemicals that all funnel into these channels. The sludge and waste is so thick in places that it prevents water from percolating underground, or poisons the water table when it does.

“And that’s what we’re dealing with for hundreds of kilometers in Delhi,” Gupta says.

The Yamuna itself is largely disconnected from the city, partitioned by embankments and hidden under highways. But a vast number of the city’s poor have taken up residence on the dangerous side of the berms and flood walls, squatting in the shadow world of the Yamuna’s wide, forgotten floodplains.

The gap between what’s needed and what’s supplied is largely filled by hundreds of thousands of illegal, community-dug borewells around the city—and what’s known as the “water mafia.”

The following afternoon, as a blue sky emerges from the brown-orange particulate haze for the first time in days, young boys play cricket in a column of dirt on the eastern bank of the inky-black river. Up a small hill, a group of young women and girls picks vegetables from a small patch of green rows, next to a jumble of tin and wooden shanties.

In a 30-minute walk along this low-lying district of Delhi, near the Yudhister Setu bridge, I spot six water pumps within 200 yards of either bank of the river, one some 10 feet from the shore. Four are metal hand pumps that can reach only into the shallowest of the water tables.

These kind of wells, settlements, and crops are illegal, and hazardous. The water and soil are almost certainly contaminated by the river and drains.

Samples taken along the banks routinely show high levels of lead, mercury, and other heavy metals. Intense flash floods that seem to be increasingly common during the summer monsoons regularly inundate the plains, washing away shelters and people.

The problem with large-scale solutions

India’s states have created climate adaptation strategies that call for big changes in behavior. The southern state of Karnataka, for instance, developed a plan recommending increased use of rainwater harvesting structures, wider adoption of drip and sprinkler irrigation in agriculture, tighter restrictions on borewells, and improved sewage management to prevent water bodies and aquifers from being polluted.

Saumya Khandelwal

But experts say these plans would be incredibly difficult and expensive to implement, and inadequate even if they were realized.

India needs to overhaul the way it uses water. The dry parts of the country will have to create jobs in industries other than agriculture, which currently employs nearly half the workforce. Cities will need to build modern networks of water and sewage pipes, treatment facilities, and wetlands, and restrict development and add flood protections along waterways.

But one of the most effective ways of dealing with an erratic water supply is to add storage, says Veena Srinivasan, a senior fellow at the Ashoka Trust for Research in Ecology and the Environment. That can mean everything from small-scale, private efforts like capturing rain on rooftops to centralized, large-scale dams, canals, and reservoirs.

The federal government generally prefers the latter. The most obvious and ambitious example is known as the Indian River Inter-link, a civil engineering project costing more than 5.5 trillion rupees ($80 billion) that would stitch together more than 60 of the nation’s rivers into a network. The idea is that the government could smooth out imbalances across thousands of miles, sloshing water from a flooded area on one side of the country to a drought-gripped region on the other.

The concept dates back to the 19th century, but it’s getting a boost from Prime Minister Narendra Modi, who pushed through approvals for the first phase. Critics say it’s a boondoggle in the making, driven more by the political appeal of a silver-bullet solution than by any scientific evidence that it will work.

Saumya Khandelwal

In a nation as large and spread-out as India, any broadly workable strategy requires better water management at local levels, Srinivasan says. That means capturing and filtering rainwater in tanks; rehabilitating lakes, ponds, and rivers; and using both to recharge aquifers. “You’ve got to rely on groundwater, which means you’ve got to figure out ways to manage it,” she says.

Bangalore's sewage miracle

On a morning in early March, Vishwanath Srikantaiah leads me on a tour around Jakkur Lake, a bowling-pin-shaped body of water in Bangalore.

Srikantaiah, a 55-year-old civil engineer turned water activist, is known as the “Zen Rain Man” of the swelling megacity, in the southwestern state of Karnataka. Standing a willowy 6' 4" (1.93 meters), with a full beard and long, wavy, graying hair, he looks the part.

Along the northeastern shore, he steps off the walking path around the lake and onto a thin trail leading into the surrounding wetland, a bright green thicket of cattails, water hyacinth, and alligator grass.

About a hundred yards down the trail, he gestures toward a channel at the edge of the grasses, where a stream of burbling water feeds into the lake. “You can see it’s absolutely clear water coming in,” he says.

Saumya Khandelwal

Days earlier it was raw sewage.

Most of Bangalore’s water is pumped up from the Cauvery River, around 100 kilometers south of the city. But about 40% of the residents rely on groundwater, largely drawn up from hundreds of thousands of borewells plunging into the ground throughout the city. The growing population has placed enormous strains on that resource both by sucking it up faster than it can be replenished and by polluting the water bodies that recharge it.

Srikantaiah helped form Bangalore’s Rainwater Club in 1991 to help people install rooftop rainwater harvesting systems. They’re little more than open pipes that collect water at the ebb of an angled roof and then run it through a filter into a tank. But the water can be stored and consumed or sent down wells to replenish aquifers.

Srikantaiah and his wife, Chitra Vishwanath, an architect who focuses on ecological design, later formed a nonprofit that lobbied the city’s utility to set up a water treatment plant at the edge of Jakkur Lake. The growing neighborhood had polluted the lake for years.

The growing population has placed enormous strains on groundwater both by sucking it up faster than it can be replenished and by polluting the water bodies that recharge it.

Now wastewater runs through the plant and then down canals into the wetlands for further filtering. By the time it works its way through the thick grasses, some three days later, the water is clean enough to support commercial fishing, irrigate nearby farming, and replenish groundwater tables. The district’s residents eventually draw that water back up through borewells, run it through home reverse-osmosis machines, and use it to drink and cook.

Saumya Khandelwal

It’s not a perfect solution, Srikantaiah says, pointing to a channel of untreated sewage that bypasses the plant and runs straight into the constructed wetlands. But the lake is far healthier than it was a decade ago, and the rehabilitation effort is seen as a model for restoring other water bodies in the city.

Srikantaiah says these local projects make real differences in real lives, faster and more reliably than some long-studied, large-scale scheme. “It’s just so important that you pick a lake, start working from the bottom up,” he says. “Show something. Do something.”

Dealing with Delhi

But there’s no way to solve some of the nation’s most vexing water problems without tackling the overlapping developmental, environmental, and economic challenges all together, Gupta says. His book lays out a richly illustrated vision for rejuvenating the Najafgarh drain, a more than 50-kilometer stretch of water that winds through the western side of Delhi before flowing into the Yamuna. It and its subdrains contribute more than 60% of the pollution that pours into the river.

The proposed project would create continuous parklands along these basins, with bike paths, transit lines, markets, public space, and low-income housing alongside lush wetlands. The long green grasses would filter sewage, in conjunction with new sewer pipes and treatment plants, cleaning the water that recharges aquifers and feeds the river. It’s a grand proposal, if one that ultimately seems far-fetched. The Delhi Jal Board, the body in charge of supplying water to citizens, is struggling with far more rudimentary tasks. Instead of installing water pipes to unconnected neighborhoods, it’s often delivering water by tanker from its own borewells north of the city. The board launched an effort to restore dozens of city drains and water bodies three years ago, including many along the Najafgarh, but has completed only one pilot project to date.

A major, multi-department effort to clean up the Yamuna starting in the 1990s failed to measurably cut pollution, despite costing billions of dollars. Many of the planned sewage plants weren’t built or didn’t work, an outcome variously blamed on poor coordination, corruption, or the inability to halt mushrooming development along the drains.

In the next three years, the city must finalize the “Master Plan for Delhi 2041,” creating a legally binding document that will guide development and planning for the coming decades. Rehabilitating the Yamuna will be one of the highest water priorities in the plan, says Jagan Shah, director of the National Institute for Urban Affairs, the agency overseeing the effort.

Saumya Khandelwal

“But it’s not an easy exercise to pull off,” he acknowledges, nodding to the many earlier failures. “The scenario is not encouraging.”

As Gupta drives past the slums of the Nizamuddin neighborhood, a collection of tents and shacks that dump waste directly into the Barapullah drain, I ask if, in his most honest moments, he really believes that Delhi will clean up the Yamuna.

“As an architect I have to be optimistic,” says Gupta, who is 48. “But don’t ask me for a time line. Because sometimes I don’t think it will be in my lifetime.”