Context:

• The Central Ground Water Board (CGWB) has released its Annual Groundwater Quality Report 2025, based mainly on nearly 15,000 groundwater samples collected during the pre-monsoon and post-monsoon periods of 2024.

Key Points:

• Objective of the Report: To evaluate groundwater quality, identify sources of contamination, and highlight its impacts on health and agriculture.
• According to the report, India’s groundwater is facing a triple contamination challenge, mainly due to pollutants like nitrate, fluoride and uranium.
• Over 28% of total samples were found above one or more permissible parameters, indicating a serious threat to public health.
• However, groundwater is largely safe for agricultural use.
• Sample collection: A total of 340 hotspots (polluted locations) were monitored. Both pre-monsoon and post-monsoon samples were collected to assess seasonal variation.
• Assessment Standards: Testing was done based on BIS (Bureau of Indian Standards) drinking water norms. Major parameters included pH, TDS, nitrate (NO3), fluoride (F), uranium (U), iron (Fe), arsenic (As), etc.
• The biggest concern is the rising uranium level in northwestern India (Punjab, Haryana, Delhi) and widespread nitrate pollution across the country.

Major Contaminants and Their Trends

Uranium – An Emerging Threat:

• National Condition: Around 13–15% of samples had uranium levels above the safe limit (30 ppb – parts per billion).
• Hotspots: Punjab, Haryana, Delhi and Rajasthan.
• Punjab: The most affected state. About 62.5% post-monsoon samples reported dangerously high uranium levels.
• Cause: Mainly geogenic (natural), but excessive groundwater extraction and declining water levels increase concentration. Alkaline soil and bicarbonates help uranium dissolve in water.

Nitrate – The Most Widespread Pollutant:

• Prevalence: The most widely spread contaminant in India. About 20.7% samples exceeded the 45 mg/L limit.
• Most affected states: Rajasthan (50.5%), Karnataka (45.5%), and Tamil Nadu (36.3%).
• Cause: Completely anthropogenic (human-made). Major causes include overuse of fertilisers (urea), sewage leakage, and animal waste.

Fluoride:

• Status: Around 8.05% samples exceeded the safe limit (1.5 mg/L).
• Affected regions: Rajasthan, Telangana and Andhra Pradesh. In Rajasthan, 41% samples were affected.
• Source: Mostly natural (from rocks).

Salinity / Electrical Conductivity:

• Status: Around 7.23% samples showed high salinity.
• Affected Areas: Arid and semi-arid regions – especially western Rajasthan, Delhi and Gujarat.
• Impact: Highly saline water is unfit for drinking and irrigation as it destroys soil fertility.

Heavy Metals:

• Arsenic: A major concern in the Ganga–Brahmaputra plains (West Bengal, Bihar, Assam).
• Lead: Highest contamination recorded in Delhi, possibly linked to industrial waste and battery recycling.
• Manganese and Iron: Found above limits in several regions, especially Assam and eastern India.

Regional Distribution and Hotspots:

• Northwestern India is the primary hotspot for uranium contamination due to geological factors, groundwater depletion and deep pumping. Excessive fertiliser use in Punjab also increases uranium leaching.
• Punjab: 62.5% samples affected by uranium – highest in India; nitrate also widespread.
• Haryana: 40–50% uranium; high fluoride.
• Delhi: 13–15% samples contaminated with uranium (24 out of 83 > 30 ppb). Delhi uses 125 MGD groundwater daily, increasing health risks. The report marks Delhi as the third most affected region.
• Uttar Pradesh/Rajasthan: Uranium + fluoride hotspots.
• South India (Tamil Nadu, Karnataka, Chhattisgarh): Mostly geogenic uranium; lower nitrate.
• Eastern India: Low overall contamination but nitrate increasing.

Analysis of Causes:

• Anthropogenic Causes: Agriculture (fertiliser/pesticide runoff – 87% groundwater used for irrigation), industrial waste, urbanisation.
• Geogenic Causes: Rock weathering, pollutants emerging from deeper layers due to groundwater depletion. India’s groundwater extraction is 60.4% (unchanged since 2009), worsening the situation.
• Seasonal Impact: Some improvement due to monsoon recharge, but no improvement in areas with insufficient rainfall.

Recommendations:

• Monitoring: Continue grid-based monitoring of 340 hotspots; increase annual surveys.
• Treatment: Ion exchange / reverse osmosis technology for uranium removal; promote organic farming to control nitrate.
• Policy Measures: Regulate fertiliser subsidies; make rainwater harvesting mandatory; develop alternate water sources in affected areas (e.g., Yamuna linking).
• Research: Geochemical mapping and study of climate change impacts.

Health Impacts of Contaminants Above Permissible Limits

Central Ground Water Board (CGWB):

• Headquarters: Faridabad, Haryana
• Established: 1970 (renamed from Exploratory Tube Well Organization)
• Nodal Ministry: Ministry of Jal Shakti
• Role: Management, exploration, monitoring and regulation of groundwater resources in India
• Also acts as the Central Ground Water Authority (CGWA) established under the Environment Protection Act, 1986.