Water resources

The first principle

Only the yearly flow of water is renewable, not its stock. Rain and snowmelt refill rivers and aquifers every year, and a region stays safe as long as it withdraws less than that recharge, at the places and times it needs it. A water crisis therefore rarely means that water has vanished; it means that withdrawal has outrun recharge, that the water is polluted, or that rain falls in one short season and runs off to the sea.

The core

How much water there is

• About 97.5 per cent of the earth's water is salt water. Of the 2.5 per cent that is fresh, roughly two thirds is locked in ice and almost a third is groundwater, so rivers and lakes hold well under 1 per cent of all freshwater.
• India has about 18 per cent of the world's population but about 4 per cent of its freshwater. Of an average annual resource of about 1,999 billion cubic metres (BCM), terrain and the short monsoon let only about 1,122 BCM be used, and irrigation takes close to four fifths of withdrawals.

What water stress means

• Malin Falkenmark's indicator measures renewable water per person per year: below 1,700 cubic metres a country is water stressed and below 1,000 it faces scarcity. India's availability fell from about 5,177 cubic metres in 1951 to about 1,545 in 2011, so India as a whole is stressed and many basins are scarce.
• The Central Ground Water Board (CGWB) compares annual extraction with recharge and classifies each block as safe (up to 70 per cent), semi critical (70 to 90), critical (90 to 100) or over exploited (above 100). In 2023 about 11 per cent of units were over exploited, though the national figure was about 59 per cent.

Why the world faces a freshwater crisis

Demand has grown with population, cities and irrigated farming, which alone takes about 70 per cent of global withdrawals. Usable supply is shrinking because sewage and industrial waste pollute rivers, aquifers are mined faster than they refill, and climate change makes rain erratic while glaciers that feed summer flows retreat. Access is a separate failure, since weak pipes, pricing and governance leave about 2 billion people without safely managed drinking water (UN World Water Development Report, 2023), and shared rivers turn upstream dams into downstream disputes. In 2018 Cape Town, after three dry years, came close to "Day Zero", when taps would be shut, and escaped only through drastic rationing.

Dimensions

Why water stress differs across India

• Rainfall regime. Rainfall ranges from over 2,500 millimetres on the Western Ghats to under 300 in western Rajasthan, and nearly all of it falls in about four months, so regions without storage face a long dry season even after a good monsoon.
• Rock and aquifer type. The Indo Gangetic plain sits on hundreds of metres of alluvium with huge storage, while about two thirds of India is hard rock (granite, gneiss, basalt) holding water only in a thin weathered layer and fractures. Such wells fill fast and dry within a season, which is why Marathwada and Telangana depend on tankers in drought years.
• Demand. Paddy in Punjab and sugarcane in Maharashtra need a great deal of water, free farm power removes the cost of pumping, and cities like Chennai and Bengaluru draw far more than local recharge.

Groundwater decline in the Gangetic valley and food security

The Gravity Recovery and Climate Experiment (GRACE), twin satellites that sense tiny changes in the earth's gravity, showed that north west India lost about 109 cubic kilometres of groundwater between 2002 and 2008 (Rodell and others, Nature, 2009), and CGWB data put Punjab's extraction at about 164 per cent of recharge in 2023. The cause is a rice wheat rotation made profitable by assured procurement, cheap tube wells and free power on a plain that receives only 500 to 700 millimetres of rain. As the water table falls, farmers must buy deep submersible pumps, so costs, power use and debt rise, small farmers lose access first, and arsenic from deeper aquifers in the middle Ganga plain enters drinking water and rice. Since Punjab and Haryana supply a large share of the wheat and rice that feed the public distribution system, their aquifers are effectively a national food reserve, and their depletion threatens food security across India.

In practice

Making urban water harvesting work

Harvesting adds to the recharge side of the balance, but in cities it works only when it is enforced, maintained and linked to the aquifer. Tamil Nadu made rooftop harvesting mandatory in 2003, and Chennai's shallow water levels rose in the following years, though later lapses show that inspection matters more than one time certificates. Bengaluru's crisis in March 2024, when thousands of borewells failed, shows the cost of losing the tank chains that once stored runoff, so desilting tanks and protecting lake beds in master plans restore both storage and flood control. Recharge pits, permeable paving and open spaces keep rain on site, while metering, leak control and reuse of treated wastewater for industry cut demand.

Schemes and committees

• Atal Bhujal Yojana (2019, Ministry of Jal Shakti): community led groundwater management in stressed blocks of seven states, with incentives tied to measured results.
• Jal Shakti Abhiyan: Catch the Rain (2021, Ministry of Jal Shakti): building and repairing harvesting structures before each monsoon in every district.
• Atal Mission for Rejuvenation and Urban Transformation (AMRUT) 2.0 (2021, Ministry of Housing and Urban Affairs): universal urban tap water, water body revival and wastewater reuse.
• The Mihir Shah Committee (2016) recommended a unified National Water Commission, and the Model Groundwater Bill (2016) proposed treating groundwater as a common pool resource rather than a landowner's property.

River interlinking: a critical look

The National Perspective Plan of 1980 proposed moving water from surplus to deficit basins, and 30 links have been identified, 14 Himalayan and 16 peninsular. The Ken Betwa link, approved in December 2021, is the first under construction.

Supporters argue that links can carry flood water towards drought prone basins and add irrigation, drinking water, hydropower and waterways. Critics point out that the Daudhan reservoir will submerge part of the Panna Tiger Reserve, villages will be displaced, costs are huge, states rarely agree on who has a surplus, and the supposed surplus and deficit basins often have good and bad monsoons in the same years. A few well studied links may help, but local storage, watershed work and efficient irrigation deliver water faster and cheaper.

Water in South Asia: asset and source of conflict

• Indus Waters Treaty (1960). Brokered by the World Bank, it gave India the eastern rivers and Pakistan the western rivers; after the Pahalgam terror attack India placed it in abeyance in April 2025.
• Ganga Water Treaty (1996). It shares lean season flows at Farakka with Bangladesh and expires in December 2026, so renewal is a live issue, while a Teesta deal drafted in 2011 was never signed.
• Brahmaputra. China began a very large hydropower project on the lower Yarlung Tsangpo near Medog in July 2025, raising Indian concern about lean season flows and flood data.
• Cooperation. Hydropower from Bhutan (Chukha, Tala, Mangdechhu) earns Bhutan its largest export revenue and gives India clean power, whereas the Pancheshwar project under the Mahakali Treaty (1996) with Nepal remains unbuilt.

Issues and way forward

• Free power and assured procurement drive over extraction. Farmers have no reason to save water, so metered power with direct benefit transfer and better prices for pulses, millets and maize can shift the cropping pattern.
• Groundwater is treated as private property. A few deep borewells can drain a shared aquifer, which is why the Mihir Shah Committee and the Model Groundwater Bill recommended community management of aquifers as common pools.
• Fragmented institutions. Surface and groundwater are planned by separate bodies, so a unified National Water Commission, as the Mihir Shah Committee proposed, remains relevant.
• Wasteful irrigation. Flood irrigation loses much of what is applied, and micro irrigation under the Pradhan Mantri Krishi Sinchayee Yojana (2015) and direct seeded rice can raise crop per drop.
• Transboundary tension. Data sharing and basin level cooperation, which work with Bhutan, need to be built with Bangladesh before the Ganga treaty lapses.

Common confusions

• Stress and scarcity. On the Falkenmark scale stress begins below 1,700 cubic metres per person and scarcity, the more severe state, below 1,000.
• Availability and utilisable water. Availability (about 1,999 BCM) is all renewable water; utilisable water (about 1,122 BCM) is what terrain and timing allow India to capture.
• Harvesting and recharge. Harvesting stores rain in tanks for use; recharge sends it underground, and only recharge raises the water table.

For the exam

• Keyword bank: Falkenmark indicator, stage of groundwater extraction, over exploited block, alluvial versus hard rock aquifer, cone of depression, GRACE, rice wheat rotation, rooftop rainwater harvesting, National Perspective Plan, Ken Betwa link, Indus Waters Treaty in abeyance, Ganga Water Treaty renewal, Medog dam.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction (data): India supports about 18 per cent of the world's people with about 4 per cent of its freshwater, and its per capita availability is already below the stress threshold of 1,700 cubic metres.
  • Introduction (judgement, quote or report): NITI Aayog's Composite Water Management Index (2018) warned that about 600 million Indians face high to extreme water stress.
  • Conclusion: India's water problem is less a shortage of rain than a failure to store, share and price it, so the answer lies in recharge, demand management and cooperative governance.
  • Conclusion: Treating aquifers and rivers as shared commons, within villages and across borders, is the only way to keep a renewable resource renewable.