FAQ on arsenic contamination in India: Causes, impacts, and mitigation options

Arsenic (As) is a naturally occurring metalloid element found widely in the Earth's crust, soil, and minerals. It is highly toxic in its inorganic form, which is the form typically found in contaminated groundwater. Arsenic is odourless, colourless, and tasteless when dissolved in water, meaning people cannot detect its presence without chemical testing.

Arsenic is a major concern in India, particularly as a water quality issue, because of the widespread contamination of groundwater, which is a primary source of drinking water and irrigation for millions of people.

a. Widespread contamination (geogenic source)

The primary cause of high arsenic levels in groundwater across the Gangetic and Brahmaputra River plains is geogenic (naturally occurring) in origin.

• Mechanism: The most accepted theory is the reductive dissolution of iron oxyhydroxides (FeOOH). Arsenic naturally adsorbs (sticks) to these iron compounds in the sediments (alluvial deposits) of the aquifers. When the groundwater conditions become reducing (low oxygen), often due to microbial activity breaking down organic matter, the iron oxyhydroxides dissolve, releasing the toxic, inorganic arsenic into the water.

• Affected Regions: States severely affected by this natural contamination, with concentrations often exceeding the permissible limits, include West Bengal, Bihar, Uttar Pradesh, Jharkhand, and Assam.

b. Severe health risks (Arsenicosis)

Long-term exposure (chronic intake) to inorganic arsenic through contaminated drinking water or food prepared with it leads to severe health conditions collectively known as arsenicosis. Arsenic is a confirmed human carcinogen.

Key health effects include:

• Skin lesions: The most characteristic initial symptoms are changes in skin pigmentation (melanosis) and the development of hardened patches or nodules on the palms and soles (keratosis).

• Cancers: Increased risks of various cancers, especially of the skin, lungs, bladder, and kidney.

• Other chronic effects: Association with cardiovascular disease, neurological problems (numbness/tingling), diabetes, and reproductive disorders.

c. Drinking water standards

India's permissible limit for arsenic in drinking water (in the absence of an alternative source) is 0.05 mg/L or 50 µg/L, although the desirable limit is the World Health Organization (WHO) guideline of 0.01 mg/L or 10 µg/L. Millions of people in the affected regions consume water far exceeding these limits.

d. The tubewell crisis

In the past, efforts to reduce surface water contamination (which carried bacterial diseases) led to the installation of millions of shallow tube wells for safer water. However, in many areas, these shallow aquifers turned out to be the ones heavily contaminated with naturally occurring arsenic, resulting in a large-scale public health crisis.

Arsenic contamination is predominantly a geogenic (natural) groundwater issue that affects the alluvial plains of two major river systems: the Ganges and the Brahmaputra.

Geographical hotspots

The most severely affected areas are concentrated in the Lower and Middle Gangetic Plains and the Brahmaputra River Basin. This contamination belt is part of a larger South and   Asian arsenic crisis that also includes Bangladesh.

Major affected states

The states with the most widespread and severe arsenic contamination are:

Arsenic in groundwater is mainly of geogenic origin — that is, naturally mobilized from rocks and sediments. The process occurs when:

• Reducing conditions (low oxygen environments) in aquifers cause arsenic-bearing iron oxides to dissolve, releasing arsenic into groundwater.

• Excessive groundwater extraction for irrigation and domestic use lowers the water table, alters redox conditions, and accelerates arsenic release.

• In some areas, industrial waste and use of arsenic-based pesticides add to the contamination.

Thus, the problem is not primarily industrial pollution, but a hydrogeochemical process intensified by human activities like over-pumping.

The health effects of arsenic exposure, primarily from long-term consumption of contaminated drinking water (a condition called arsenicosis), are severe and affect nearly every major organ system. Inorganic arsenic is classified as a human carcinogen by the World Health Organization (WHO).

Major Chronic Health Effects

The symptoms often take years to develop (typically 5 to 10 years or more of exposure).

• Skin Lesions & Changes (Most Characteristic Initial Sign):

  • Hyperpigmentation: Darkening or spots of skin, often on the palms, soles, and torso ("raindrop" pigmentation).

  • Hyperkeratosis: Thickening or hard patches on the palms of the hands and soles of the feet, which can progress to skin cancer.

• Cancers (Carcinogenic Effects):

  • Significantly increased risk of various internal and external cancers, especially:

    • Skin cancer (Basal and Squamous cell carcinoma)

    • Lung cancer

    • Bladder and Kidney cancer

    • Liver cancer (Angiosarcoma)

• Cardiovascular Disease:

  • Hypertension (high blood pressure)

  • Atherosclerosis and peripheral vascular disease (often leading to "Blackfoot Disease"—gangrene in the limbs).

  • Heart disease.

• Neurological Effects:

  • Peripheral neuropathy (numbness, tingling, and weakness, particularly in the hands and feet, often in a "stocking-and-glove" pattern).

• Other Systemic Effects:

  • Diabetes (Type 2)

  • Liver damage (non-cirrhotic portal fibrosis)

  • Negative impacts on cognitive development in children exposed in utero or early childhood.

Acute Arsenic Poisoning

This occurs from ingesting a single, large, toxic dose (not typical of chronic water contamination). Symptoms are rapid and include:

• Severe vomiting and diarrhoea ("rice-water" stools)

• Abdominal pain

• Muscle cramps

• Neurological symptoms (seizures, delirium)

• Circulatory failure (shock) and potentially death.

The problem of arsenic contamination in groundwater is widespread across India, affecting many states and districts. Here are the key points regarding its extent:

• Geographical spread: Arsenic contamination has been reported in parts of 25 States and Union Territories, covering over 230 districts (data points can vary slightly over time).

• Major concentration zones: The most severe and widespread contamination is predominantly located in the alluvial plains of the major river basins, including:

  • Ganga-Brahmaputra River basin: States like West Bengal, Bihar, Uttar Pradesh, Jharkhand, and Assam are highly affected. West Bengal was the first state to report contamination and still has a significant number of affected areas and population.

  • Other affected states: The issue is also significant in states such as Punjab and Haryana, and sporadic occurrences are noted in states like Chhattisgarh, Karnataka, and Gujarat.

• Population at risk: Studies have estimated that a very large population is exposed to high levels of arsenic. One study suggested that over 250 million people across the country could be exposed to groundwater arsenic above the permissible limit.

• Type of contamination: The majority of the contamination (90%) is found in alluvial aquifers (geological formations of clay, silt, and sand), particularly in the shallow to medium depth range of up to 100 meters. A smaller percentage is found in hard-rock regions.

While the most severe and concentrated areas are in the eastern states within the Gangetic and Brahmaputra plains, the issue of groundwater arsenic contamination is a national public health challenge with varying degrees of severity across nearly two dozen states and union territories.

Detection involves a combination of field test kits and laboratory analysis:

• Field Test Kits (FTKs): Used for rapid village-level screening of handpumps and wells; inexpensive but less precise.

• Laboratory testing: Conducted by state Public Health Engineering Departments (PHEDs), CGWB, and accredited labs for confirmation.

• GIS-based mapping and monitoring: Under programs like National Water Quality Sub-Mission (NWQSM) and Jal Jeevan Mission, data is being digitised to track contaminated sources and ensure alternative safe supply.

India has adopted a multi-pronged approach to address arsenic contamination:

A. Alternative safe water supply

• Surface water schemes: Shift from contaminated shallow groundwater to treated surface water (e.g., Ganga, Brahmaputra, or canals).

• Piped Water Supply (PWS): Under Jal Jeevan Mission (JJM), households are connected to centralized systems using tested safe sources.

• Deep aquifer tapping: Safe deeper aquifers (>100 m) are identified for use where feasible.

B. Arsenic removal technologies

• Community and household filters using adsorption, ion exchange, or oxidation methods (e.g., activated alumina, iron-coated sand).

• Centralized treatment plants in arsenic-affected blocks (e.g., West Bengal and Bihar have hundreds of installed units).

C. Institutional and programmatic initiatives

• National Water Quality Sub-Mission (NWQSM) (2017): Targets arsenic and fluoride mitigation in priority districts.

• Arsenic and Fluoride Removal Technologies Catalogue developed by CSIR-NEERI, IITs, and UNICEF.

• Periodic surveillance by the Department of Drinking Water & Sanitation (DDWS) and CGWB through online platforms like the IMIS (Integrated Management Information System).

D. Awareness and health interventions

• Public awareness campaigns on safe water use (avoiding handpumps in red-marked areas).

• Medical camps and long-term health monitoring in chronic exposure zones.

• Inclusion of arsenic testing in School and Anganwadi water safety protocols.

Yes, there have been several successful arsenic mitigation efforts in India, primarily focusing on providing alternative safe water sources and implementing specialised filtration technologies. The success, however, is often characterised by a mix of technological effectiveness and sustainable community participation.

Successful Technological and Institutional Models

1. Community and Domestic Filtration Technologies

• AMRIT (Arsenic and Metal Removal by Indian Technology): Developed by IIT-Madras, this technology uses nano-scale iron oxy-hydroxide to selectively remove arsenic.

  • It has been successfully field-tested and implemented in West Bengal (Murshidabad and Nadia districts) for both community-level and domestic use, delivering arsenic concentrations below the WHO standard at a very low cost.

• IIT-Bombay Filters (using Iron Nails): Researchers developed simple, low-cost filters that attach to existing handpumps. The method uses elemental iron (iron nails) to chemically bind and remove arsenic.

  • Trials in West Bengal and Bihar showed that these filters could reduce arsenic levels drastically, and they are designed to be built and maintained by local communities, enhancing sustainability.

2. Alternative Safe Water Sources

• Deep Tube Wells: A primary and often highly successful long-term strategy involves drilling to deeper, uncontaminated aquifers (typically below 150 meters) and properly sealing off the shallower, arsenic-rich layers.

  • The Central Groundwater Board (CGWB) has successfully constructed hundreds of such arsenic-safe wells across the affected states, including Bihar, West Bengal, and Uttar Pradesh, under the NAQUIM (National Aquifer Mapping & Management Programme).

• Surface Water Treatment: In some highly affected areas, such as the Madhusudankati village in West Bengal, projects successfully shifted from groundwater to treating pond (surface) water using modern filtration to provide clean, arsenic-free, and affordable drinking water.

3. Government Initiatives

• Jal Jeevan Mission (JJM): This major Government of India mission aims to provide safe and potable tap water supply to every rural household. In arsenic-affected areas, the strategy prioritizes:

  • Piped water supply schemes based on alternative safe surface water sources (rivers).

  • Installation of Community Water Purification Plants (CWPPs) as an interim measure in all affected habitations until long-term tap connections are fully operational.

Key Challenge: While the technology is proven, the long-term success of community-level solutions often hinges on consistent maintenance, sludge disposal, and community buy-in. The shift towards bulk piped water supply from treated surface sources is the most sustainable large-scale solution.

The main challenges remaining in arsenic mitigation in India are complex, spanning technical, financial, socio-economic, and governance issues.

Technical and Operational Challenges

• Failure of Arsenic Removal Units (ARUs): Many installed community- or household-level ARUs fail to work effectively or stop functioning soon after installation due to poor maintenance, lack of spare parts, or inadequate technical capacity for operation and upkeep by local communities.

• Arsenic Speciation Complexity: Arsenic in groundwater primarily exists as the highly toxic and mobile arsenite (As(III)) and the less toxic arsenate (As(V)). Most removal technologies are more efficient at removing As(V), making it challenging to treat water where As(III) is predominant without pre-oxidation.

• Sludge Disposal: Arsenic removal generates toxic, arsenic-laden sludge. Safe and sustainable disposal of this hazardous waste is a major challenge, as improper disposal can lead to secondary contamination of soil and water bodies.

• Monitoring and Reliability: There is a lack of real-time water quality monitoring to ensure treated water consistently meets safety standards. Testing is often infrequent, leading to people consuming contaminated water unknowingly.

Socio-Economic and Financial Challenges

• Low Public Awareness: Despite being a widespread issue, many people, especially in rural areas, are unaware of the non-immediate, long-term health risks of arsenic contamination (Arsenicosis). They may mistake symptoms for other diseases, leading to continued use of unsafe water sources.

• Lack of Alternatives and Financial Burden: In affected regions, people often have no viable alternative water source and cannot afford commercial treated water. The economic burden of arsenic-related illnesses (healthcare costs, loss of productivity due to sickness) also traps families in poverty.

• Social Stigma: Individuals with visible arsenicosis symptoms (like skin lesions) face social stigma, affecting their marriage prospects, employment opportunities, and overall well-being.

• Willingness to Pay and User Fees: Establishing sustainable models for community-based water treatment plants requires the collection of user fees for maintenance, but people are often reluctant or unable to pay, leading to the plants' failure.

Policy and Governance Challenges

• Focus on 'Hardware' over 'Safety': Mitigation efforts often prioritize the installation of new infrastructure (like Arsenic Removal Units) over ensuring its long-term functionality, maintenance, and water quality safety.

• Decentralized and Fragmented Approach: Effective mitigation requires coordinated efforts across different departments (water, health, agriculture). A fragmented, non-holistic approach hinders comprehensive and sustainable solutions.

• Contamination in the Food Chain: Groundwater is used extensively for irrigation, causing arsenic to enter the food chain (especially through rice), which is a major, often overlooked, source of exposure that current policies don't fully address.

Transboundary Nature: The Indo-Gangetic Plain, where contamination is most severe, is a large, transboundary aquifer system (spanning India, Bangladesh, and Nepal), necessitating regional cooperation for hydrogeological solutions.

Addressing arsenic contamination is not just the responsibility of government agencies—it also depends on informed and active communities. Individual vigilance and collective action can greatly reduce exposure risks and strengthen the long-term safety of rural water systems.

A. Ensure safe household water use

• Test every drinking-water source regularly. Use Field Test Kits (FTKs) available through Panchayats, PHED, or Village Water & Sanitation Committees (VWSCs). Mark each source safe (blue) or unsafe (red) after testing.

• Use only safe or treated water for drinking and cooking—avoid mixing safe and unsafe water in the same vessel.

• Do not drink from newly dug handpumps or shallow tube wells until they are tested, especially in high-risk areas.

B. Promote and maintain alternative safe water sources

• Adopt piped or community water supply systems that draw from tested safe aquifers or surface water.

• Encourage rainwater harvesting at household and school level for supplementary use.

• Maintain household or community filters properly clean sand, replace cartridges, and ensure drainage of reject water away from wells.

• Report non-functional filters or broken piped connections promptly to the Gram Panchayat or Jal Jeevan Mission (JJM) helpline.

C. Strengthen local monitoring and accountability

• Participate in the Village Water and Sanitation Committee (VWSC) or Pani Samiti under the Jal Jeevan Mission. Every VWSC is responsible for O&M, water quality testing, and maintaining a register of sources.

• Encourage women and youth groups (e.g., SHGs, school eco-clubs) to monitor and report water quality results publicly on notice boards.

• Work with Panchayats to ensure that Water Safety and Security Plans (WSSPs) are prepared and updated annually.

D. Reduce groundwater stress

• Avoid over-pumping groundwater for irrigation—especially from shallow aquifers (<50 m) prone to arsenic release.

• Promote water-saving irrigation practices (e.g., Direct Seeded Rice, alternate wetting and drying) that reduce groundwater drawdown.

• Support recharge structures such as soak pits, percolation tanks, and rooftop harvesting to maintain natural groundwater levels.

E. Raise awareness and educate others

• Disseminate simple messages in schools, anganwadis, and health camps about arsenic’s health effects and prevention.

• Display wall paintings, posters, or colour codes on handpumps to help families identify safe sources easily.

• Share success stories (e.g., villages that switched to piped surface water) to motivate nearby communities.

F. Seek early medical help

• Anyone showing symptoms such as skin patches, thickened palms/soles, or chronic fatigue should consult a doctor or health worker immediately. Early detection and nutritional support can limit long-term impacts.

• Eat a balanced diet rich in protein, vitamins A, C, E, and folate, which can reduce arsenic absorption and toxicity.

G. Collaborate with institutions

• Partner with NGOs, universities, or local laboratories conducting water testing and awareness drives.

• Participate in community science initiatives that help map contaminated wells and update public databases.

• Advocate for transparency in data sharing—districts should publicly display water-quality maps and lab results.

In essence, individuals can protect their families through awareness and safe-water habits, while communities can institutionalize vigilance through VWSCs and Panchayats. Together, these grassroots actions complement government programs like Jal Jeevan Mission and the National Water Quality Sub-Mission, moving India closer to the goal of safe, arsenic-free water for all by 2030.

India’s fight against arsenic contamination is entering a new phase — one that goes beyond temporary filtration and piecemeal mitigation toward systemic, science-based, and community-owned water security. The next decade will determine whether arsenic contamination remains a localized crisis or is transformed into a model of climate-resilient water governance.

A. From reactive mitigation to preventive management

Until now, most efforts have focused on identifying contaminated sources and providing alternative water through filters or new bore wells. The next step is to prevent contamination before it reaches the user by managing groundwater extraction, recharge, and aquifer health.

• Under the National Aquifer Mapping and Management Programme (NAQUIM), the Central Ground Water Board (CGWB) is preparing aquifer-scale arsenic vulnerability maps, identifying both safe and unsafe zones for drinking-water extraction.

• These maps will guide district-level water source planning, ensuring that new schemes under Jal Jeevan Mission (JJM) and Swajal avoid high-risk aquifers.

• The focus will gradually shift from reactive well replacement to preventive zoning, land-use regulation, and source protection.

B. Scaling surface-water–based piped supply systems

The future lies in transitioning from groundwater dependence to surface water networks that are climate- and contamination-resilient.

• The Jal Jeevan Mission is already investing in regional piped water schemes drawing from major rivers such as the Ganga, Brahmaputra, and their tributaries.

• States like West Bengal, Bihar, and Assam are piloting large-scale multi-village surface water supply schemes with centralized treatment and local storage.

• These systems will not only remove arsenic exposure but also reduce pressure on shallow aquifers, improving long-term sustainability.

However, the success of these systems depends on robust operation and maintenance (O&M) — ensuring electricity, maintenance funds, and trained local operators are consistently available.

C. Integrating arsenic mitigation into climate adaptation plans

Arsenic contamination is closely linked to climate change impacts on groundwater — such as falling water tables, longer dry spells, and altered recharge cycles.

• States are now required to integrate water-quality risks into State Action Plans on Climate Change (SAPCCs) and District Climate Action Plans (DCAPs).

• Climate-resilient aquifer management will include rainwater harvesting, managed aquifer recharge, and conjunctive use of surface and groundwater.

• The Ministry of Jal Shakti is developing Water Security Indices that combine water quality, reliability, and sustainability parameters — providing early-warning systems for both contamination and scarcity.

D. Strengthening institutions and convergence

Future efforts will rely on strong coordination across departments — drinking water, health, rural development, and environment.

• The Department of Drinking Water & Sanitation (DDWS), CGWB, Indian Council of Medical Research (ICMR), and State Health Departments are collaborating on joint surveillance frameworks linking water quality data with health outcomes.

• Convergence with health and nutrition programs (such as the National Health Mission and Poshan Abhiyaan) will help identify vulnerable populations and improve dietary interventions to reduce arsenic toxicity.

• Over time, each Gram Panchayat will be expected to maintain a Water Safety and Security Plan (WSSP) that combines engineering measures, health awareness, and source sustainability.

E. Investing in innovation and local entrepreneurship

Technological innovation will play a key role in ensuring last-mile access to safe water:

• Low-cost, low-maintenance arsenic removal units using locally available materials (e.g., iron-coated sand, bio-adsorbents) are being scaled up with the help of CSIR-NEERI and IITs.

• IoT-based real-time sensors for arsenic detection and household water-quality monitoring are emerging through startups and government-supported incubation programs.

• Local entrepreneurs and self-help groups (SHGs) are being trained to operate village-level water kiosks and manage pay-per-use safe water stations, turning arsenic mitigation into livelihood opportunities.

F. Expanding transparency and public participation

The upcoming phase of the Jal Jeevan Mission emphasizes data transparency and citizen access:

• Online dashboards will show water-quality results down to the habitation level.

• Villages will be able to monitor their own handpump test results, scheme performance, and contamination alerts.

• Public reporting platforms — through mobile apps and Gram Panchayat displays — will help ensure accountability and continuous testing.

Community-led monitoring and local data ownership will be crucial for sustaining progress once central missions phase out.

G. A long-term vision: Safe water as a climate right

Ultimately, India’s arsenic challenge is not just an issue of contamination — it is a question of environmental justice and resilience.
The vision for 2030 and beyond includes:

• Universal access to safe drinking water, aligned with SDG 6.1.

• Zero arsenic exposure in all habitations, verified through third-party audits.

• Groundwater managed as a shared resource, not an individual asset.

• Empowered communities equipped to test, plan, and manage their own water systems.

With sustained investment, scientific mapping, and grassroots participation, India can turn its most contaminated aquifers into models of restoration, accountability, and resilience.