The Central Ground Water Board (CGWB) categorizes areas based on groundwater extraction. While most of Karnataka is in the ‘safe’ or ‘semi-critical’ zone, urban pockets like Bengaluru East are classified as ‘over-exploited’ because extraction far exceeds the recharge capacity, meaning the water is being used much faster than it is being replaced by rain.

An aquifer is an underground reservoir of water. Imagine a giant underground sponge made of rock and sand that holds water. When we take out more water than the rain can put back in, the ‘sponge’ starts to dry out, leading to falling water levels and dry wells.

Bengaluru is situated on the South Karnataka Plateau, characterized by hard ‘crystalline’ rocks like granite and gneiss. Unlike alluvial plains (like the North Indian plains) where water can seep through easily, these hard rocks only have water in their cracks and fractures, making groundwater limited and difficult to replenish.

Bengaluru is located at a high altitude (about 900m above sea level), while the Cauvery river flows at a much lower level. Bringing water to the city involves pumping it over 100 km and lifting it up hundreds of meters, which requires massive infrastructure (pipelines) and huge amounts of electricity, making it very expensive.

In early 2024, Bengaluru faced one of its worst water crises in decades. Due to failing rains in 2023, the groundwater levels plummeted, and the Cauvery reservoirs reached very low levels. This led to a massive shortage, forcing thousands to rely on expensive water tankers and prompting the government to take control of private tanker operations.

The project mentioned is likely the ‘Cauvery Water Supply Scheme Phase V’, which aims to provide drinking water to 110 peripheral villages that were added to the city’s municipal limits (BBMP) years ago but lacked piped water. By providing river water, the government hopes to reduce these areas’ total dependence on borewells.

The BWSSB (Bangalore Water Supply and Sewerage Board) manages the city’s water infrastructure. One of its key initiatives involves pumping tertiary-treated (highly filtered) sewage water into seasonal lakes. This helps maintain the water level in lakes even in summer, which in turn helps recharge the surrounding groundwater table.

Grey infrastructure refers to human-engineered structures like concrete pipes, dams, and water treatment plants. Green infrastructure mimics natural systems, using parks, wetlands, and lakes to absorb rainwater and recharge the earth. In Bengaluru, massive concretization (grey) has replaced open spaces (green), leading to floods during rain and droughts later because water cannot soak into the ground.

Integrated Urban Water Management (IUWM) is a framework that suggests cities should manage all parts of the water cycle (fresh water, wastewater, and stormwater) together. Currently, Bengaluru manages them separately, which leads to inefficiencies. For example, treated wastewater is thrown away while fresh water is pumped from 100km away at great cost.