Water Resources

Why this chapter matters for UPSC: Water is where geography meets governance: the uneven spread of rainfall and rivers, the dominance of irrigation, falling water tables in the north-west, polluted rivers, inter-State disputes and the case for watershed management. Mains has asked why India suffers water scarcity though "well endowed", what water stress is and why it varies regionally, whether rainwater harvesting can solve groundwater depletion, what declining groundwater in the Gangetic valley means for food security, river linking, micro-irrigation and industrial pollution of rivers. In the 2026-27 NCERT reprint this is Chapter 4, "Water Resources"; the reprint keeps the whole chapter, updates India's population share, adds boxes on the Pradhan Mantri Krishi Sinchayee Yojana and the Atal Bhujal Yojana, and replaces the National Water Policy 2002 box with 2012.

Contemporary hook: The Central Ground Water Board's 2025 assessment found India extracting 247.22 billion cubic metres (BCM) of groundwater a year, 60.63% of the extractable resource, with 730 of 6,762 assessment units (10.8%) "over-exploited". That is an improvement on 2017, when 17.2% of units were over-exploited, but the over-exploited blocks are concentrated exactly where NCERT says groundwater use is highest: Punjab, Haryana, Rajasthan and Tamil Nadu. Wells and tube-wells now irrigate 63% of India's net irrigated area.

🧠 First Principles — Read This First

India has a lot of water in total and too little where and when it is needed. NCERT's numbers make the point: India has about 2.45% of the world's surface area, 4% of its water resources and more than 17% of its people. Precipitation gives about 4,000 cubic km a year, but only 1,869 cubic km flows in rivers and recharges aquifers, and only 1,122 cubic km can be put to use. The rest is lost to evaporation, runs off in monsoon floods the land cannot hold, or lies in basins too remote to tap. Rainfall comes in a few monsoon months and is concentrated in the east and on the Western Ghats; the north-west and the Deccan are dry. Scarcity in India is therefore mostly a problem of distribution in space and time, which is why irrigation, storage and groundwater dominate the chapter.

Agriculture uses most of the water, so it decides the outcome. Irrigation takes 89% of surface water and 92% of groundwater used in India (NCERT). Irrigation made the Green Revolution, but the same wells and tube-wells that made Punjab and Haryana the granary are drawing groundwater faster than it recharges. The second half of the chapter, quality, conservation, watershed management, rainwater harvesting and policy, is about making a finite, cyclic resource last when demand keeps rising. Remember the word cyclic: water is renewable as a flow, but an aquifer emptied faster than rain refills it behaves like a non-renewable stock.

PART 1 — Quick Reference

India's Water Budget (NCERT) and the Latest Assessments

1 cubic km = 1 billion cubic metres (BCM). NCERT says 690 cubic km is "32 per cent" of the surface water; 690 is about 37% of its 1,869. Sources: NCERT Class XII, India: People and Economy, ch. 4 (2026-27); PIB (Ministry of Jal Shakti), 29 January and 5 February 2026.

Who Uses India's Water (NCERT)

Groundwater by State (NCERT) and Status of Assessment Units (CGWB 2025)

PART 2 — Concepts & Narrative

Surface Water Resources

India's four sources of surface water are rivers, lakes, ponds and tanks. There are about 10,360 rivers and tributaries longer than 1.6 km, with a mean annual flow of 1,869 cubic km, but topographical, hydrological and other constraints allow only about 690 cubic km to be used. A river's flow depends on the size of its catchment and the rainfall in it. Because rainfall is high in their catchments, the Ganga, the Brahmaputra and the Barak together carry 60% of India's surface water although they drain only about one-third of its area. Much of the flow of the southern rivers (Godavari, Krishna, Kaveri) has already been harnessed; that of the Brahmaputra and the Ganga has not.

Groundwater Resources

India's replenishable groundwater is about 432 cubic km (NCERT). Use is relatively high in the river basins of the north-west and parts of the south: very high in Punjab, Haryana, Rajasthan and Tamil Nadu, moderate in Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra, and small relative to potential in Chhattisgarh, Odisha and Kerala. NCERT warns that if the present trend continues, demand will outrun supply, "detrimental to development" and a cause of social upheaval.

Lagoons and Backwaters

India's long, indented coast has many lagoons and lakes, with large resources in Kerala, Odisha and West Bengal. The water is generally brackish, but it is used for fishing and to irrigate certain varieties of paddy and coconut.

Water Demand and Utilisation

India has been an agrarian economy, with about two-thirds of its people dependent on agriculture, so the Five Year Plans gave irrigation very high priority, with multipurpose river valley projects such as Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar and the Indira Gandhi Canal. Agriculture accounts for 89% of surface water and 92% of groundwater used; industry for 2% and 5%; the domestic sector for 9% of surface water use. With development, the shares of industry and households are expected to rise, which is the answer to NCERT's question why agriculture's share is expected to decline.

Demand for Irrigation

Irrigation is needed because rainfall varies in space and time: the north-west and the Deccan plateau are deficient and drought-prone, winters and summers are dry over most of India, and even in wet West Bengal and Bihar, breaks in the monsoon create damaging dry spells. Some crops (rice, sugarcane, jute) need more water than rain provides. Irrigation makes multiple cropping possible, irrigated land is more productive than unirrigated land, and high-yielding varieties need assured moisture, which is why the Green Revolution succeeded first in Punjab, Haryana and western Uttar Pradesh, where more than 85% of net sown area is irrigated (NCERT).

The cost is falling water tables. Of the net irrigated area, 76.1% in Punjab and 51.3% in Haryana is irrigated by wells and tube-wells (NCERT), and over-use has lowered the water table. Over-withdrawal has raised fluoride in groundwater in Rajasthan and Maharashtra and arsenic in parts of West Bengal and Bihar. Intensive irrigation in Punjab, Haryana and western Uttar Pradesh is also increasing soil salinity.

The national picture has moved the same way. In 2023-24, 59.3% of India's net sown area (82.4 million hectares) was irrigated, up from 17.6% in 1950-51; tube-wells irrigated 48% of it and other wells 15%, so groundwater supplied 63% of net irrigated area, while canals supplied 21% and tanks 4%. In 1950-51 the leaders had been canals (39.8%), other wells (28.7%) and tanks (17.3%) (Land Use Statistics 2023-24).

Deterioration of Water Quality

Per capita availability falls as population grows, and pollution from industrial, agricultural and domestic effluents shrinks the usable supply further. Water quality means purity, water without unwanted foreign matter such as micro-organisms, chemicals and industrial wastes; such matter dissolves or stays suspended in lakes, streams, rivers and seas and can seep into groundwater.

Rivers keep better quality in their less densely populated upper, hilly stretches. In the plains their water is used intensively and drains carrying fertilisers and insecticides, domestic solid and liquid waste and industrial effluents join them; pollutant concentration is highest in summer, when flow is low. The Central Pollution Control Board with the State boards monitored water quality at 507 stations (NCERT); organic and bacterial contamination remained the main source of river pollution. NCERT names the Yamuna between Delhi and Etawah as the most polluted, and the Sabarmati at Ahmedabad, the Gomti at Lucknow, the Kali, the Adyar, the Cooum (entire stretches), the Vaigai at Madurai, the Musi at Hyderabad and the Ganga at Kanpur and Varanasi as severely polluted. Groundwater is polluted by heavy and toxic metals, fluoride and nitrates.

The laws, the Water (Prevention and Control of Pollution) Act, 1974, the Environment (Protection) Act, 1986 and the Water Cess Act, 1977, have not been implemented effectively; NCERT notes that 251 polluting industries stood along rivers and lakes in 1997. Its remedy is public awareness and action against agricultural, domestic and industrial discharges. The CPCB's latest assessment, Polluted River Stretches for Restoration of Water Quality (November 2022), identified 311 polluted stretches on 279 rivers in 30 States and UTs, of which 46 are in Priority I (biochemical oxygen demand above 30 mg per litre), down from 351 stretches in 2018. River-specific programmes and the Ganga are taken up in NCERT's last chapter (selected issues).

Water Conservation and Management

With availability falling and demand rising, and desalination too costly to count on, India must conserve: water-saving technology, prevention of pollution, watershed development, rainwater harvesting, recycling and reuse, and conjunctive use of surface and groundwater. Recycling and reuse can raise freshwater supply: industries can use reclaimed wastewater for cooling and fire-fighting, and households can use water from bathing and washing for gardens, saving better water for drinking. NCERT says recycling is practised only on a limited scale.

Watershed Management

Watershed management is the efficient management and conservation of surface and groundwater: preventing runoff and storing and recharging groundwater through percolation tanks and recharge wells. In its broad sense it covers the conservation, regeneration and judicious use of all the resources of a watershed, natural and human, to balance resources and society; its success "largely depends upon community participation". NCERT's examples: Haryali, a centrally sponsored project executed by gram panchayats with people's participation to conserve water for drinking, irrigation, fisheries and afforestation; Neeru-Meeru (Water and You) in Andhra Pradesh and Arvary Pani Sansad in Alwar, Rajasthan, which built percolation tanks, johads (dug-out ponds) and check dams; and Tamil Nadu, which made water-harvesting structures compulsory in every house.

Atal Bhujal Yojana (Atal Jal) (NCERT box, 2026-27) works in 8,220 water-stressed gram panchayats of 229 blocks or talukas in 80 districts of seven States: Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan and Uttar Pradesh, which together hold about 37% of India's water-stressed (over-exploited, critical and semi-critical) blocks. Its key aim is a change in community behaviour "from the prevailing attitude of consumption to conservation".

Rainwater Harvesting

Rainwater harvesting captures and stores rain for use and to recharge aquifers, guiding it into bore-wells, pits and wells. It is low-cost and eco-friendly; it raises availability, checks falling water tables, improves groundwater quality by diluting fluoride and nitrates, prevents soil erosion and flooding, and, where it recharges coastal aquifers, arrests salt-water intrusion. Traditional systems use lakes, ponds and irrigation tanks; in Rajasthan, the kund or tanka is a covered underground tank near the house or village. Rooftop and open-space harvesting reduce dependence on groundwater and save the energy used for pumping; urban areas benefit most, since demand already exceeds supply in most cities. NCERT adds desalination, transfer from surplus to deficit areas by interlinking rivers, and, most important for users, the pricing of water.

River Linking and Water Disputes

The Interlinking of Rivers programme under the National Perspective Plan for water resources development was formulated in 1980 to store and transfer surplus water to deficit regions; 30 link projects have been identified. Among those benefiting Rajasthan, the agreement between Rajasthan, Madhya Pradesh and the Government of India for the Modified Parbati-Kalisindh-Chambal link (integrated with the Eastern Rajasthan Canal Project) was signed on 5 December 2024. Because water is a State subject, disputes between States are referred to tribunals under the Inter-State River Water Disputes Act: 9 tribunals have been constituted so far, and 5 have submitted their reports (Ministry of Jal Shakti, February 2026). NCERT's exercise asks how depleting water can lead to such disputes: the answer is the gap between fixed flows and rising demand from irrigation and cities in neighbouring States.

The National Water Policy, 2012 (NCERT box, 2026-27)

The policy aims to assess the situation and propose a framework for action "with a unified national perspective". Its salient features, as NCERT lists them:

• a national water framework law and comprehensive legislation for inter-State rivers and river valleys;
• water, after meeting pre-emptive needs (safe drinking water and sanitation, food security, poor people dependent on agriculture for their livelihood, and minimum ecosystem needs), to be treated as an economic good to promote conservation and efficient use;
• adaptation to climate change in designing and managing water structures;
• benchmarks for water use (water footprints) and water auditing;
• removal of the large disparity between urban and rural water-supply norms;
• management of water projects and services with community participation.

(The 2021-22 text instead carried the National Water Policy, 2002, which set a priority order for allocation: drinking water, irrigation, hydropower, navigation, industrial and other uses.)

Jal Kranti Abhiyan (2015-16) aimed at water security through per capita availability, involving local bodies, NGOs and citizens: a Jal Gram (one water-stressed village) in each of 672 districts, model command areas of about 1,000 hectares in different regions, pollution abatement (conservation and artificial recharge, reducing groundwater pollution, arsenic-free wells), and mass awareness.

PART 3 — UPSC Integration

Frames that score. For "well endowed yet scarce", use NCERT's budget (4,000 → 1,869 → 1,122 cubic km) and its causes (spatial and temporal concentration, pollution, over-extraction), then the CGWB's 2025 numbers. For groundwater depletion, use NCERT's Punjab-Haryana well shares and fluoride and arsenic, then the 730 over-exploited units. For solutions, combine NCERT's watershed and rainwater-harvesting material with PMKSY and Atal Jal, and end with pricing and the 2012 policy's "economic good" principle.

Exam Strategy

For Prelims: NCERT's numbers (2.45% / 4% / 17%; 4,000, 1,869, 690, 432, 1,122 cubic km; 10,360 rivers; Ganga-Brahmaputra-Barak 60% of surface water on one-third of the area; agriculture 89% and 92%); the polluted rivers NCERT names; the three water laws and their years; Neeru-Meeru (Andhra Pradesh), Arvary Pani Sansad (Alwar), Haryali; kund or tanka (Rajasthan); Ralegan Siddhi (Ahmadnagar).

For Mains: start from distribution and use, then depletion and quality, then management, with one NCERT example and one current figure per heading.

Avoid: treating "replenishable groundwater" (NCERT's 432 cubic km) and the CGWB's "extractable resource" (407.75 BCM) as the same measure; and calling the Yamuna "India's most polluted river" without NCERT's qualifier (between Delhi and Etawah).

Practice Questions

Practice (UPSC-pattern, not past papers). Questions 1 to 3 are NCERT's own exercise MCQs.

Prelims:

1. Which one of the following describes water as a resource?
   (a) Abiotic resource
   (b) Non-renewable resource
   (c) Biotic resource
   (d) Non-cyclic resource

2. Which one of the following south Indian States has the highest groundwater utilisation (in per cent) of its total groundwater potential?
   (a) Tamil Nadu
   (b) Karnataka
   (c) Andhra Pradesh
   (d) Kerala

3. The highest proportion of the total water used in the country is in which sector?
   (a) Irrigation
   (b) Industries
   (c) Domestic use
   (d) None of the above

4. Consider the following pairs of a water-harvesting initiative and its State (NCERT):
   

   1. Neeru-Meeru : Andhra Pradesh
      
   2. Arvary Pani Sansad : Rajasthan
      
   3. Ralegan Siddhi : Gujarat
      Which of the pairs given above are correctly matched?
      (a) 1 and 2 only
      (b) 2 and 3 only
      (c) 1 and 3 only
      (d) 1, 2 and 3

5. According to the Central Ground Water Board's assessment for 2025, India's stage of groundwater extraction is about:
   (a) 40%
   (b) 61%
   (c) 85%
   (d) 108%

6. NCERT names which river as the most polluted in India, between Delhi and Etawah?
   (a) Ganga
   (b) Yamuna
   (c) Gomti
   (d) Sabarmati

Answer notes: Q4, Ralegan Siddhi is in Ahmadnagar district, Maharashtra; Q5, 247.22 ÷ 407.75 = 60.63%.

Mains:

1. Discuss the availability of water resources in India and the factors that determine their spatial distribution. (250 words)
2. What factors explain the high groundwater development of Punjab, Haryana and Tamil Nadu, and what are its consequences? (150 words)
3. What is watershed management? Can it play an important role in sustainable development? Illustrate with an Indian example. (250 words)

📦 Revision Capsule

Sources

• NCERT, India: People and Economy (Class XII), ch. 6 "Water Resources" (2021-22 print) and ch. 4 (Reprint 2026-27): 2021 book archive, Wayback copy; 2026-27 book archive.
• PIB (Ministry of Jal Shakti), "Dynamic Groundwater Resources Assessment, 2025", 29 January 2026: pib.gov.in; "Availability of Surface and Groundwater Resources", 5 February 2026: pib.gov.in.
• Ministry of Agriculture and Farmers Welfare, Land Use Statistics at a Glance 2023-24, Table IV (source-wise irrigated area): revised final, Wayback copy.
• Central Pollution Control Board, Polluted River Stretches for Restoration of Water Quality - 2022: cpcb.nic.in PDF.