Arsenic and Heavy Metals in Drinking Water in India: Risks, Hotspots and How to Remove Them
Of all the things that can be in drinking water, arsenic is among the most feared, and for good reason. It is invisible, tasteless and odourless, it accumulates in the body over years, and in parts of India it sits in the groundwater that millions of people drink every day. Lead and other heavy metals carry similar risks. This guide explains what these contaminants are, why they are so serious, where in India they are concentrated, and how to remove them from the water you drink.
This is general information, not medical advice. If you live in an affected area and have health concerns, consult a doctor and have your water tested.
What Are Arsenic and Heavy Metals in Water?
Arsenic is a naturally occurring element found in the earth’s crust. In India’s affected belts it leaches from sediment into groundwater, so the contamination is natural and geological rather than industrial, which is why it follows the river basins. Heavy metals such as lead, mercury, cadmium and chromium can enter water both naturally and from industrial discharge, old plumbing and fittings, or contaminated land.
What these contaminants share is that they are toxic at very low concentrations and that the body cannot easily get rid of them. They build up over time, which is why the safe limits are tiny and why long-term exposure is the real danger.
Why Arsenic Is So Dangerous
Arsenic is dangerous for three reasons that combine badly.
First, it is completely undetectable by sight, taste or smell, so contaminated water looks and tastes perfectly normal. People drink it for years without any warning.
Second, it is a cumulative toxin. There is no safe casual level; the harm comes from steady, long-term intake. The BIS limit is just 0.01 mg/L (10 micrograms per litre), matching the World Health Organization guideline, precisely because even small amounts add up.
Third, the health effects are severe. Long-term arsenic exposure causes arsenicosis, with characteristic skin lesions and pigmentation changes, and significantly raises the risk of skin, bladder and lung cancers. It is also linked to cardiovascular disease and to developmental harm, which makes it especially concerning for children, as our guide to safe drinking water for children discusses.
The takeaway: arsenic is invisible, cumulative and seriously toxic, with a BIS limit of just 0.01 mg/L. In affected areas, the only safe assumption is that untreated groundwater may carry it, and the only way to be sure is to test and treat.
Where Arsenic Is High in India
Arsenic contamination in India follows the great river plains, where the sediment carries arsenic into the groundwater. The most affected regions are:
| Region | Status | Notes |
|---|---|---|
| West Bengal (Ganga delta) | Severely affected | One of the world’s most studied arsenic-affected regions |
| Bihar (Gangetic plain) | Severely affected | Widespread contamination along the river belt |
| Uttar Pradesh (eastern districts) | Affected | Concentrated in the Gangetic floodplain |
| Jharkhand and Assam | Affected pockets | Along the Ganga and Brahmaputra systems |
| Other river-plain pockets | Localised | Scattered hotspots in several states |
Because the contamination is geological and tied to the river systems, it affects borewell-dependent communities across these belts. To see the live, government-sourced reading for your city, open your water quality report, for example Kolkata water quality. Arsenic also commonly appears alongside high TDS and other contaminants in groundwater, so our borewell water guide is a useful companion read.
Arsenic in groundwater is tracked in the CGWB Annual Ground Water Quality Report and is the focus of dedicated mitigation efforts in the worst-affected states. As with fluoride, the contamination is natural, persistent and concentrated in specific geological belts, so the reading for your exact location is what matters.
Other Heavy Metals to Know About
Arsenic is the headline, but a few other contaminants belong in the same conversation:
- Lead (BIS limit 0.01 mg/L): can leach from old pipes, solder and brass fittings. It is especially harmful to children’s brain development, so it matters even where the supply itself is clean but the plumbing is old.
- Iron (BIS limit 0.3 mg/L): not a toxic heavy metal in the way arsenic and lead are, but very common in eastern and coastal groundwater. It causes a metallic taste, rust-coloured staining and turbidity.
- Mercury, cadmium and chromium: rarer, usually linked to industrial discharge or contaminated land, and toxic at low levels.
The good news is that the same technology that removes arsenic also removes lead and these other dissolved metals, so a single correct solution covers the whole group.
How to Know If Your Water Has Arsenic or Heavy Metals
Since arsenic and lead are invisible and tasteless, testing is the only way to be sure:
- Check government groundwater data for your district to know whether arsenic is likely in your area. See the live reading for your city on our water quality checker.
- Get a laboratory test from a NABL-accredited lab for arsenic and heavy metals, especially if you are on borewell or groundwater in the Ganga or Brahmaputra belts.
- Consider your plumbing for lead specifically: very old fittings and solder are the usual source, independent of the supply.
If you are in a known arsenic belt, do not wait for symptoms; arsenicosis appears only after years of exposure, by which point significant intake has already occurred.
How to Remove Arsenic and Heavy Metals
As with fluoride, the simpler methods do not work for arsenic and heavy metals:
- Boiling does not remove arsenic or heavy metals and slightly concentrates them as water evaporates.
- UV only inactivates microorganisms and does nothing to dissolved metals.
- Carbon filters and UF leave dissolved arsenic and heavy metals largely untouched.
- Reverse osmosis is the reliable home technology: its membrane physically removes dissolved arsenic, lead and other heavy metals along with dissolved solids, and a good unit balances minerals back afterwards.
For arsenic-affected groundwater, an RO purifier rated for your local TDS, with output verified by testing, is the practical answer. To understand how the technologies differ, see our RO vs UV vs UF guide; for the related contaminants in groundwater, see our fluoride guide.
Live in an arsenic-affected belt? Check the live, government-sourced reading for your pincode, then match an RO purifier rated for it.
Why Boon Removes Heavy Metals Safely
Boon is a water-technology company founded by ex-IIT Kanpur engineers and backed by the Technology Development Board (Government of India), NITI Aayog and Roca, with systems serving more than 4,000 organisations worldwide. Its home purifiers, Boon Tap and Boon Tall, are built for the high-TDS groundwater of India’s arsenic and fluoride belts.
8-Stage UltraOsmosis Rated to 2,000 ppm
Boon’s 8-stage UltraOsmosis process removes dissolved arsenic, lead and other heavy metals along with fluoride, nitrate and dissolved solids, then balances minerals back so the water is safe and pleasant. Boon Tall is rated for input up to 2,000 ppm TDS, suited to the heavy groundwater of the eastern river plains.
WaterAI Monitoring
For contaminants you cannot see, knowing your purifier is working matters. Boon’s WaterAI app tracks input and output water quality and filter health in real time and alerts you when a filter genuinely needs changing. WaterAI won the iF Design Award 2026.
Free Professional Installation
Boon’s technicians measure your input water, install the unit and verify output quality at no extra cost, so the purifier is matched to your real water from day one and you can confirm arsenic and heavy metals are being removed.
Remove arsenic and heavy metals the reliable way: Boon’s 8-stage UltraOsmosis, rated to 2,000 ppm, with mineral balancing, WaterAI monitoring, and free professional installation.
Frequently Asked Questions
What is the safe limit for arsenic in drinking water in India?
Under BIS IS 10500, the acceptable limit for arsenic is 0.01 mg/L, which is 10 micrograms per litre, the same as the WHO guideline. This is a very low threshold because arsenic is a cumulative toxin with no safe casual level. Where no alternative source exists, BIS allows a permissible maximum of 0.05 mg/L, but the goal should always be to get as close to zero as possible.
Why is arsenic in drinking water so dangerous?
Arsenic is dangerous because it is a cumulative poison with no taste, colour or smell, so people drink contaminated water for years unknowingly. Long-term exposure causes arsenicosis, with skin lesions and pigmentation changes, and raises the risk of skin, bladder and lung cancers, along with cardiovascular and developmental effects. Because the damage builds up slowly and silently, arsenic is one of the most serious water contaminants in India’s affected belts.
Which areas of India have high arsenic in groundwater?
Arsenic contamination is concentrated in the Ganga and Brahmaputra river plains. The worst-affected areas include West Bengal, Bihar, Uttar Pradesh, Jharkhand and Assam, with additional pockets in other states. It is a natural geological contamination of groundwater rather than an industrial one, which is why it follows the river basins and affects borewell-dependent communities.
Does boiling or UV remove arsenic and heavy metals from water?
No. Boiling does not remove arsenic or heavy metals and slightly concentrates them as water evaporates. UV only inactivates microorganisms and does nothing to dissolved metals. Ordinary carbon filters and UF membranes also leave dissolved arsenic and heavy metals largely untouched. The reliable home technology for removing them is reverse osmosis.
How do I remove arsenic from drinking water at home?
The reliable home method is a reverse osmosis purifier. The RO membrane removes dissolved arsenic along with lead, other heavy metals and dissolved solids, and a good unit then balances minerals back for taste and health. If you live in an arsenic-affected belt such as the Ganga or Brahmaputra plains, use an RO purifier rated for your local TDS and have your water tested to confirm the output is safe.
Can heavy metals in water be detected by taste or colour?
Mostly no. Arsenic and lead have no taste, colour or smell, which is why they are so dangerous. Iron is an exception and often gives a metallic taste and rust-coloured staining, but the toxic heavy metals that matter most for health are invisible. The only way to know whether your water contains arsenic or lead is a laboratory test, supported by government groundwater data for your area.
Boon Tall: 8-stage UltraOsmosis rated to 2,000 ppm, with mineral balancing, WaterAI monitoring, and free professional installation. Built to remove arsenic and heavy metals from India’s groundwater.
