There are not many cities that can run out of water in April and struggle with flooding by September.
Bengaluru has lived with that contradiction for years.
But long before tankers, pipelines and pumping stations, the city had found a way to manage both problems at once. More than 500 years ago, it developed an interconnected network of stormwater canals called Rajakaluves that linked lakes across the landscape. During heavy rains, excess water flowed naturally from one lake to another instead of flooding streets. In drier months, the same system helped replenish groundwater and store water for the future.
One surviving stretch of this historic network is the K100 waterway.
Once an open drain carrying nearly 130 million litres of untreated sewage every day, it has now been restored into a thriving public corridor where people walk, birds have returned, and rainwater once again has space to flow.
Its revival is not just cleaning up a neglected canal. It is bringing back a centuries-old water management system that once allowed Bengaluru to thrive without a major river.
A city built around rain
Long before water was pumped from the Cauvery, Bengaluru relied almost entirely on rainfall.
In the 16th century, the city’s founder, Kempe Gowda, developed a network of interconnected Rajakaluves that channeled excess rainwater from one lake to another through Bengaluru’s natural valleys.
Instead of letting rainwater rush away, the system slowed its flow, stored it across a chain of lakes, recharged groundwater, and reduced flooding.
For centuries, this network helped the city balance water supply and flood management.
But as Bengaluru expanded, many of these canals gradually disappeared beneath roads and buildings. Others became narrower, while several were turned into sewage channels instead of stormwater drains.
The K100 waterway was no exception.
Over the years, it came to carry nearly 130 million litres of untreated sewage every day. Solid waste accumulated along its banks, and the canal became known more for its foul smell than for the role it once played in Bengaluru’s water system.
Cleaning the water before cleaning the canal
Restoring the K100 meant tackling the pollution first.
The project brought together the Karnataka government, the Bruhat Bengaluru Mahanagara Palike (BBMP), the Bangalore Water Supply and Sewerage Board (BWSSB), the MOD Foundation, and several technical partners.
The first step was to stop sewage from entering the canal.
The waterway was desilted, decades of accumulated waste were removed, and new sewer infrastructure was built to divert wastewater away from the stormwater channel. Sewage treatment capacity was also expanded, reducing the amount of untreated sewage entering the canal from about 130 million litres a day to around 5 million litres.
Only after improving the water quality did work begin on the surrounding landscape.
Pedestrian walkways were added along long stretches of the canal. Trees were planted to create shaded public spaces, and neglected edges were transformed into accessible areas where people could once again reconnect with the water.
Today, the K100 has become a nearly 12-kilometre-long green-blue corridor that blends ecological restoration with public space.
A blueprint hidden in plain sight
Bengaluru’s water challenges are not new.
More than 500 years ago, the Rajakaluve system was designed to address many of the same problems the city faces today. By connecting lakes across Bengaluru’s valleys, it allowed excess rainwater to move naturally through the landscape while replenishing groundwater.
In an interview withSouth First, urban designer Naresh Narasimhan, who conceived the K100 Citizen’s Waterway Project, said Bengaluru already has an extensive water network—it simply stopped functioning the way it was designed to.
The city receives around 900 to 1,000 millimetres of rainfall every year. Yet much of that water mixes with untreated sewage in stormwater drains before eventually reaching downstream lakes.
Once an open drain carrying nearly 130 million litres of untreated sewage every day, it has now been restored into a thriving public corridor where people walk, birds have returned, and rainwater once again has space to flow. Photograph: (Mod Foundation)
According to Narasimhan, treating wastewater as a resource rather than waste is essential for a city that frequently faces water shortages.
The K100 project reflects that shift in thinking.
Rather than viewing a stormwater drain as forgotten infrastructure, it reimagines it as part of a living water system that can improve environmental health while creating valuable public spaces.
Its success also highlights a much bigger opportunity.
Bengaluru still has more than 842 kilometres of Rajakaluves, many of which continue to connect the city’s historic chain of lakes.
Environmental experts have long argued that restoring these canals, alongside rejuvenating Bengaluru’s lakes, could improve groundwater recharge, strengthen the city’s water security, and reduce urban flooding.
The K100 alone will not solve Bengaluru’s water crisis.
But it offers an important reminder that some of the city’s most effective climate solutions are not new. They have been part of Bengaluru’s landscape for centuries, waiting to be restored rather than reinvented.
