Why this chapter matters for UPSC: Water runs through GS1 (resources, droughts and floods), GS2 (drinking-water schemes) and GS3 (groundwater, river pollution, disaster management), and Mains has asked why a water-rich India still suffers scarcity and what falling groundwater means for food security. This chapter supplies the basic science: the water cycle, where usable water comes from and why it is limited. It was dropped from NCERT's rationalised 2023-24 edition; evaporation and condensation survive in the separation chapter, and the water cycle, floods, droughts and rainwater harvesting are no longer in the Class VI book. BharatNotes keeps it because the topic is central to the syllabus.

Contemporary hook: The 2026 south-west monsoon ended with all-India rainfall of 87% of its long period average (759.4 mm), below normal and the 4th lowest since 2001 (IMD, 30 September 2026). A weak monsoon is exactly the situation in which this chapter's ideas, groundwater, drought and harvesting rain, decide how a region copes.

🧠 First Principles — Read This First

NCERT opens with a thought experiment: what if your family got only one bucket of water a day for a week? We use water for drinking, brushing, bathing, washing utensils and clothes, toilets and cleaning; and, less visibly, to grow wheat, rice, pulses and fibre crops and to make almost everything in factories. Paheli adds that about two glasses of water go into producing each page of a book.

All of it comes in the end from the same sources: ponds, lakes, rivers and wells. These are filled by the water cycle: the sun evaporates water from oceans and land, plants transpire it, it condenses into clouds and returns as rain, hail or snow. About two-thirds of the Earth is covered by water, but most of it is the saline water of oceans. The total amount of water on Earth stays the same, yet the water available for use is limited and shrinking with over-use. Hence floods, droughts, and the need to conserve and harvest rain.

PART 1 — Quick Reference

The Water Cycle (NCERT)

StepWhat happensNCERT example
EvaporationWater turns to vapour from all open surfaces, faster in sunlight; the salts stay behindTwo plates of water, in sun and shade: both dry, the sunny one first
TranspirationPlants release part of the water they take up as vapourAbout 500 litres are transpired by the wheat plants that give 1 kg of wheat
CondensationAir cools as it rises; vapour condenses into droplets that float as cloudsDrops on the outside of a glass of iced water; dew; fog
PrecipitationDroplets join into heavier drops and fall as rain, or in special conditions as hail or snow
ReturnSnowmelt and rain flow as streams and rivers, mostly back to the sea; some fills lakes and ponds; some seeps into the groundGround water feeds open wells, handpumps, tubewells and many lakes

The circulation of water between ocean and land is the water cycle; it maintains the supply of water on land.

India's Water: Official Figures

MeasureFigureSource
Average annual rainfall (all-India)1,160.1 mm (1971-2020 normal)IMD
Average annual water resource1,999.20 BCM (1985-2015 basis)CWC, 2019 reassessment
Utilisable water1,137 BCM = 690 BCM surface + 447 BCM replenishable ground waterCWC
Per capita availability1,486 m³ (2021), 1,367 m³ (2031, projected)CWC study, via Jal Shakti (2024)
Annual ground-water recharge448.52 BCM (2025 assessment)CGWB
Annual ground-water extraction247.22 BCM; stage of extraction 60.63% (2025)CGWB
Share of extraction for irrigation87% (215.10 BCM); domestic 11%; industry 2% (2025)CGWB

CWC's older estimate (about 1,869 BCM of resource and 1,123 BCM utilisable) was replaced by the 2019 reassessment.

PART 2 — Concepts & Narrative

Where Does the Water in the Tap Come From?

Tap water is drawn from a lake, a river or a well and supplied through pipes, so every home ultimately depends on the same ponds, lakes, rivers and wells. NCERT quotes Coleridge's Rime of the Ancient Mariner (1798), "Water water every where / Nor any drop to drink", for sailors lost on the salty ocean. Yet the oceans supply our fresh water: evaporation leaves the salt behind, and the vapour returns as fresh rain.

Key Term

Evaporation (NCERT Class IX): the change of a liquid into vapour at any temperature below its boiling point. It happens at the surface. Its rate increases with:

  • larger surface area (we spread clothes to dry them);
  • higher temperature;
  • lower humidity;
  • higher wind speed.

Evaporation causes cooling: water in an earthen pot (matka) stays cool in summer, and a desert cooler works best on a hot, dry day. Boiling, by contrast, happens throughout the liquid at a fixed temperature: 100 °C (373 K) for water at atmospheric pressure.

Ground Water and the Water Table (NCERT Class VII)

Rain that soaks into the ground fills the spaces in the soil and rock. The process of seeping into the ground is infiltration. The upper level of the water-filled layer is the water table, which may be less than a metre or several metres deep. Water below it is ground water; where it is stored between layers of hard rock it forms an aquifer, tapped by tubewells and handpumps.

The water table stays put as long as we draw only as much as rain replenishes. It falls when extraction exceeds recharge: with more people, industry and agriculture, scanty rainfall, deforestation, and concrete that blocks seepage. NCERT Class VI already warns that the more handpumps and tubewells an area has, the deeper we must dig.

UPSC Connect

Ground water in 2025 (CGWB, Dynamic Ground Water Resources of India, 2025): of 6,762 assessment units, 4,946 (73.14%) are safe, 758 (11.21%) semi-critical, 201 (2.97%) critical, 730 (10.80%) over-exploited and 127 (1.88%) saline. So about a quarter of units are under stress. Agriculture takes 87% of all ground-water extraction.

Atal Bhujal Yojana (Atal Jal): a Central Sector Scheme for community-led ground-water management in seven States: Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan and Uttar Pradesh, for five years from 1 April 2020. NCERT Class X notes that these States held about 37% of India's water-stressed blocks. After a slight extension, the scheme's tenure has ended (Jal Shakti, 30 December 2025).

Floods and Droughts

Most of India's rain falls in the monsoon, and the sowing of many crops waits for it. Too much rain raises rivers, lakes and ponds until water spreads over large areas: floods submerge fields, forests, villages and cities and kill crops, animals and people; animals in the water get stranded on land and die when the flood recedes. No rain for a long period dries the soil by evaporation and transpiration, lowers ponds and wells and makes ground water scarce: drought, when food and fodder become hard to get.

Key Term

Four kinds of drought (IMD):

  • Meteorological drought: seasonal rainfall over an area less than 75% of its long-term average. Moderate if the deficit is 26-50%; severe if it exceeds 50%.
  • Hydrological drought: stream flows inadequate to supply established uses of water.
  • Agricultural drought: soil moisture inadequate for healthy crop growth, causing stress and wilting.
  • Socio-economic drought: water shortage that disrupts the economy and the social fabric: unemployment, migration, discontent. Meteorological, hydrological and agricultural droughts often lead to it.

Conserving Water and Harvesting Rain

NCERT's case for conservation: only a small fraction of Earth's water is usable; most is in the oceans; ground water lowered too far cannot be used; and demand rises with population, food production and industry. Hence long queues for water in many cities.

Rainwater harvesting means collecting rainwater and storing it for later use. Its basic idea: "Catch water where it falls." NCERT describes two techniques:

  1. Rooftop rainwater harvesting: pipes carry roof water to a storage tank (filter it before use), or straight into a pit so it recharges ground water.
  2. Roadside drains that let rainwater go directly into the ground.
Explainer

Traditional and modern harvesting (NCERT Classes VII and X):

SystemWhereWhat it does
Guls / kulsWestern HimalayasDiversion channels for agriculture
Inundation channelsFlood plains of BengalIrrigate fields with floodwater
KhadinsJaisalmerFields turned into rain-fed storage that moistens the soil
JohadsOther parts of RajasthanSame principle as khadins
TankasBikaner, Phalodi, BarmerUnderground tanks fed by rooftop harvesting, for drinking water
BawrisRajasthan (NCERT VII)Traditional step-reservoirs; fell into disuse, now being revived
Bamboo drip irrigationMeghalayaA 200-year-old system: 18-20 litres entering the bamboo pipes reach plants as 20-80 drops a minute
Drip irrigationFarmsNarrow tubes deliver water directly at the base of the plant (NCERT VII)

Case studies NCERT gives: in Bhujpur (Kutch, Gujarat), villagers and an NGO built eighteen check-dams on the Rukmavati river and its tributaries in 1989; percolation recharged the aquifers and wells have water again. In Gendathur (Mysuru district, Karnataka), nearly 200 households harvest rooftop rain. Tamil Nadu was the first State to make rooftop rainwater harvesting compulsory for all houses. In Shillong, near the world's rainiest places (Cherrapunjee and Mawsynram, 55 km away), nearly every household harvests rooftop rain because the city still faces acute shortage.

Jal Sanchay Jan Bhagidari, a people's-participation initiative under the Jal Shakti Abhiyan: Catch the Rain campaign, was launched at Surat on 6 September 2024.

UPSC Connect

People behind the movement: Rajendra Singh, who revived johads in Rajasthan, received the Ramon Magsaysay Award for Community Leadership in 2001 and the Stockholm Water Prize in 2015. Rani-ki-Vav, the step-well at Patan (Gujarat), was inscribed on the UNESCO World Heritage List in 2014. NCERT Class VII notes that 22 March is celebrated as World Water Day, and that 2003 was the International Year of Freshwater.

Drinking Water for Every Home: Jal Jeevan Mission

UPSC Connect

Jal Jeevan Mission (JJM) aims at a tap-water connection for every rural household. On 10 March 2026, the Union Cabinet extended it up to December 2028, raising the total outlay to ₹8.69 lakh crore with central assistance of ₹3.59 lakh crore (up from ₹2.08 lakh crore approved in 2019-20), and restructured it from building infrastructure to delivering service. At that date, of 19.36 crore rural households, about 15.80 crore (81.61%) had tap connections, against 3.23 crore (17%) in 2019.

Clean Rivers: Namami Gange and Water-Quality Classes

UPSC Connect

Namami Gange was approved as a flagship programme in June 2014 with ₹20,000 crore; its second phase carried ₹22,500 crore, and the official record describes it as extended to March 2026. As of February 2026, 524 projects costing ₹43,030 crore had been sanctioned and 355 completed; 138 sewage-treatment projects with 4,050 MLD capacity were operational (Jal Shakti, April 2026). The National Mission for Clean Ganga implements it.

CPCB's "designated best use" classes for surface water:

ClassBest useKey criteria
ADrinking-water source without conventional treatment but after disinfectionDO 6 mg/l or more; BOD 2 mg/l or less; total coliforms 50 MPN/100 ml or less
BOutdoor bathing (organised)DO 5 mg/l or more; BOD 3 mg/l or less; coliforms 500 or less
CDrinking-water source with conventional treatment and disinfectionDO 4 mg/l or more; BOD 3 mg/l or less; coliforms 5,000 or less
DPropagation of wildlife and fisheriesDO 4 mg/l or more; free ammonia 1.2 mg/l or less (no BOD criterion)
EIrrigation, industrial cooling, controlled waste disposalpH, conductivity, sodium absorption ratio, boron

BOD (biochemical oxygen demand) measures the oxygen that microbes use to break down organic matter in water: the higher the BOD, the heavier the organic pollution. DO is the dissolved oxygen available to aquatic life. For how a city cleans its drinking water, see Separation of Substances.

What the Policy Says: National Water Policy, 2012

The National Water Policy, 2012 treats safe water for drinking and sanitation as a "pre-emptive" need, followed by high-priority allocation for other basic domestic needs (including animals), food security, sustenance agriculture and minimum ecosystem needs; the rest is allocated to promote conservation and efficient use. In December 2021 the Jal Shakti Ministry said the 2012 policy remained in effect while a revision was being drafted.

PART 3 — UPSC Integration

The water cycle explains why rain is fresh though the sea is salty, and why the same rain is lost if it runs off concrete instead of soaking in. Ground water is the hinge between the science and the policy: CGWB's 2025 figures show agriculture taking 87% of extraction and about a quarter of assessment units under stress, which is why community schemes (Atal Jal), harvesting campaigns (Catch the Rain) and the revival of johads and bawris matter. Floods and the four kinds of drought connect to disaster management; a below-normal monsoon like 2026's shows how a meteorological shortfall can become agricultural and socio-economic drought. Jal Jeevan Mission and Namami Gange are the two big programmes on drinking water and river health. Mains answers should name the process, give a dated figure and cite one scheme and one case study.

Exam Strategy

Prelims traps:

  • Evaporation happens at all temperatures below boiling, faster with heat, wind, low humidity and a larger surface; boiling is at 100 °C (373 K) at atmospheric pressure.
  • Transpiration is a part of the water cycle: ~500 litres for the wheat behind 1 kg of grain (NCERT).
  • Water table = top of the saturated layer; aquifer = ground water stored between rock layers; infiltration = seepage into the ground.
  • IMD meteorological drought: rainfall below 75% of normal; moderate 26-50% deficit; severe above 50%.
  • CGWB 2025: extraction 247.22 BCM; stage of extraction 60.63%; irrigation 87%; 730 over-exploited units (10.80%).
  • CWC 2019: 1,999.20 BCM resource; 1,137 BCM utilisable (690 surface + 447 ground).
  • CPCB Class A = drinking source without conventional treatment (after disinfection); Class C = with conventional treatment.
  • Khadins = Jaisalmer; johads = rest of Rajasthan; guls/kuls = Western Himalayas; bamboo drip = Meghalaya; tankas = Bikaner, Phalodi, Barmer.
  • Tamil Nadu was the first State to make rooftop rainwater harvesting compulsory.
  • JJM: extended to December 2028; 81.61% coverage (March 2026).

Mains angle: Examine why India, with abundant rainfall, still suffers water scarcity, or how falling ground water threatens food security and what community recharge can do.

Practice Questions

Practice (UPSC-pattern, not past papers). Real UPSC questions on this chapter are listed in the PYQ box above.

Prelims:

  1. Which of the following increase the rate of evaporation?

    1. Increase in surface area
    2. Increase in humidity
    3. Increase in wind speed
      Select the correct answer using the code below:
      (a) 1 and 2 only
      (b) 1 and 3 only
      (c) 2 and 3 only
      (d) 1, 2 and 3

  2. According to IMD, meteorological drought over an area is a situation in which seasonal rainfall is:
    (a) less than 90% of its long-term average
    (b) less than 75% of its long-term average
    (c) less than 50% of its long-term average
    (d) zero for at least one month

  3. Consider the following pairs (traditional water harvesting : region):

    1. Khadins : Jaisalmer
    2. Guls or kuls : Western Himalayas
    3. Bamboo drip irrigation : Meghalaya
      How many of the pairs given above are correctly matched?
      (a) Only one
      (b) Only two
      (c) All three
      (d) None

  4. In CPCB's water-quality classification, Class A denotes:
    (a) A drinking-water source usable without conventional treatment, after disinfection
    (b) A drinking-water source usable only after conventional treatment
    (c) Water fit for wildlife and fisheries
    (d) Water fit only for irrigation and industrial cooling

  5. As per CGWB's 2025 assessment, the largest share of India's ground-water extraction is used for:
    (a) Domestic supply
    (b) Industry
    (c) Agriculture (irrigation)
    (d) Thermal power

  6. The water found stored between layers of hard rock below the water table is called:
    (a) Infiltration
    (b) An aquifer
    (c) Run-off
    (d) Condensate

  7. Which State was the first in India to make rooftop rainwater harvesting compulsory for all houses?
    (a) Rajasthan
    (b) Gujarat
    (c) Tamil Nadu
    (d) Meghalaya

Mains (UPSC-pattern):

  1. "India is water-rich but water-stressed." Examine with reference to rainfall, ground water and per-capita availability. (150 words)
  2. How can community recharge structures and traditional harvesting systems address ground-water depletion? Illustrate with examples. (150 words)

📦 Revision Capsule

Revision Capsule

Hard Facts

  • Water cycle: evaporation + transpiration → condensation (clouds) → rain, hail, snow → rivers, lakes, ground water → oceans
  • ~2/3 of Earth covered by water (NCERT VI); most is saline
  • ~500 L transpired for 1 kg of wheat; ~2 glasses of water per book page (NCERT)
  • Rainwater harvesting: "Catch water where it falls"; rooftop harvesting and roadside drains
  • CGWB 2025: 6,762 units; 730 over-exploited; extraction 247.22 BCM; irrigation 87%
  • CWC 2019: 1,999.20 BCM; utilisable 1,137 BCM; per capita 1,486 m³ (2021)
  • JJM: to December 2028; ₹8.69 lakh crore; 81.61% coverage (10-Mar-2026)
  • 2026 monsoon: 87% of LPA (below normal)

Core Concepts

  • Usable water is limited even though total water is constant
  • Ground water falls when extraction exceeds recharge
  • Floods from excess rain; drought from long absence of rain; four kinds of drought
  • Traditional systems and check-dams recharge aquifers

Confused Pairs

  • Evaporation (surface, any temperature) vs boiling (bulk, fixed temperature)
  • Water table vs aquifer
  • Meteorological vs hydrological vs agricultural vs socio-economic drought
  • CPCB Class A (no conventional treatment) vs Class C (with treatment)
  • Khadin (Jaisalmer) vs johad (Rajasthan) vs kul (Himalaya)

PYQ Pattern

  • Mains has asked why India suffers water scarcity (2015), how micro-watersheds help in drought-prone areas (2016), the Jal Shakti Abhiyan (2020) and declining Gangetic ground water and food security (2024).

Sources

Sources