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WaterSeverity: High

Lake loss and water stress in Bengaluru

A city far from major rivers depends on distant pumped water and depleted groundwater, while many of its historic lakes have been lost or polluted.

Bengaluru · India

01 · The problem

What is happening

Bengaluru historically relied on a network of interconnected man-made lakes (tanks) that stored monsoon rainfall. Rapid urban growth has seen many lakes encroached on, disconnected or filled, while others receive untreated sewage — Bellandur Lake became widely known for toxic foam and fires. Municipal supply is pumped from the Cauvery River, far away and at a much lower elevation, and does not reach all parts of the city, so many households and businesses rely on borewells and private water tankers. A weak monsoon preceding 2024 led to acute shortages across parts of the city in early 2024.

High severity. Serious, widespread effects requiring sustained action. Severity is descriptive editorial metadata summarising documented effects. It is not a measured index or a score.

02 · Causes

Why it is happening

  1. 01

    Rapid and unplanned urban expansion

    Growth outpaced water, sewerage and drainage infrastructure, especially in peripheral areas.

  2. 02

    Encroachment on lakes and their channels

    Building on lake beds and stormwater channels breaks the cascade that once connected the lakes.

  3. 03

    Untreated sewage

    Wastewater entering lakes causes eutrophication, foaming and odour.

  4. 04

    Groundwater over-extraction

    Heavy reliance on borewells lowers water tables where recharge is limited.

03 · Impacts

Who and what it affects

  1. 01

    Water shortages and costs

    Households dependent on tankers face higher costs and unreliable supply during dry periods.

  2. 02

    Urban flooding

    Loss of lakes and blocked channels reduces the city's capacity to absorb heavy rainfall.

  3. 03

    Degraded ecosystems and public health risks

    Polluted lakes lose biodiversity and create health and nuisance risks for nearby residents.

04 · Solutions

Documented approaches

  1. Lake rejuvenation

    Desilting, sewage diversion, restored inlets and outlets and community stewardship of lakes.

    Expected effectCan restore storage, recharge and ecological function where sustained.

  2. Treated wastewater reuse

    Using treated wastewater to fill lakes and recharge groundwater in surrounding districts.

    Expected effectReduces pressure on freshwater and supports groundwater levels.

  3. Rainwater harvesting requirements

    Mandatory rooftop rainwater harvesting for buildings above a certain size.

    Expected effectIncreases local recharge and reduces peak runoff.

Explore an illustrative What-If

05 · Key indicators

What can be measured

No reliable quantitative indicator is included for this issue. TerraLens shows figures only where a credible source supports them — consult the sources below for current data.

06 · Sources

Where this comes from

  1. [1]Bangalore Water Supply and Sewerage BoardGovernment of Karnatakabwssb.karnataka.gov.in(opens in a new tab)
  2. [2]Central Ground Water BoardGovernment of Indiacgwb.gov.in(opens in a new tab)
  3. [3]Bruhat Bengaluru Mahanagara PalikeGovernment of Karnatakabbmp.gov.in(opens in a new tab)

Links open the publishing organisation's site. Some point to the publisher's main page, where the named report or dataset can be found.

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