जल कवच Jal Kavach, a shield for water
Jal Kavach is a filter the size of your palm. It clamps onto an ordinary tap, or screws onto a bottle, and in independent lab tests it removed 99.9999% of E. coli. It needs no electricity, wastes no water and costs about 10 paise a litre. Foundations, CSR teams and the armed forces use it to reach homes that RO purifiers were never built for.
Figures from distribution records, as of November 2026. Many filters sit on a tap that several families share, at a school, a health centre or a village stand-post, so one filter often serves more than one family.
In Chapar, in Assam’s Dhubri district, families fill their pots from river channels the colour of tea. In the villages around Kotma in Madhya Pradesh, women pour every pot of drinking water through a cloth, then wash the cloth. Every day.
Across rural and low-income urban India, water comes from a hand pump, a tanker, a shared tap or a river. Families boil it when they can afford the fuel, or drink it as it is. Waterborne illness costs them school days, wages and, too often, a child.
An RO purifier costs many thousands of rupees, needs a plug point and pours most of the water down the drain. It was never built for these homes. Jal Kavach was.
Inside every Jal Kavach is a membrane with pores just 0.1 micron wide, about a thousand times thinner than a human hair. Water passes through. Bacteria and protozoa don’t.
Tested at the Shriram Institute for Industrial Research (NABL-accredited), June 2025: E. coli cut from 2.1 million to under 1 per ml (99.9999%), turbidity from 4.8 to 0.2 NTU, and TDS unchanged. Read the full test report (PDF, 0.6 MB, report no. C1/0000396239). Born from research at MIT.
| Feature | Jal Kavach | RO purifier | Boiling | Cloth straining |
|---|---|---|---|---|
| Removes bacteria | Yes, 99.9999% of E. coli in lab tests | Yes | Yes | No |
| Removes salts, arsenic | No | Yes | No | No |
| Needs electricity or fuel | No | Electricity | Fuel, every day | No |
| Water wasted | None | Most of it | None | None |
| Keeps natural minerals | Yes | No | Yes | Yes |
| Upfront cost | Under ₹1,000 | Many thousands of rupees | A pot and a stove | A cloth |
Most of our filters reach families through foundations and CSR programmes. These are a few of the places, and what we learned on the way.
Dhubri district, Assam · October 2026
In six riverine villages, where families draw water from muddy channels, we showed every household how to fit and use the filter, and handed out about 150 in two days. The foundation’s own field staff watched how simple it was, and now run the distribution themselves.
That handover is the part we are proudest of. It is how a programme grows without our team at every doorstep.
10 states · January to July 2026
With a family foundation’s rural scholarship programme, we tested sample units in coordinators’ homes first, then sent filters home with 1,000 students. Families rated it 4.3 out of 5 in the first survey.
Seven states and Puducherry · 2026
For one of India’s largest corporate foundations, we made and shipped 10,565 filters to ten sites, and trained local staff at each one to run the distribution.
Kotma, Madhya Pradesh · October 2026
A doctor joined our demonstration at the local hospital and recorded a short video with the team. Nearby, women who strain every pot through cloth were glad to stop.
Rajasthan and the North-East · 2025–26
Field-demonstrated with the Indian Army in the Thar Desert, ordered by an infantry battalion, and trialled by the ITBP and the Indian Navy.
Short videos the team shot on their phones, shared here as they came in. No editing, no music.
You know the villages and the people. We test the water, supply the filters at programme pricing, train your field staff, and give you the records your board will ask for.
Download the 2-page programme brief PDF, 0.8 MB
For a programme of around 10,000 tap filters, Jal Kavach is ₹600 a filter plus 18% GST, with shipping charged at cost (about ₹15 a filter). Pilots and smaller programmes are priced by size. Ask for a quote for your numbers.
Most partners start with 10 sample filters, then a pilot of a few hundred families in one district. Our largest programme so far is 10,565 filters across ten sites.
“The water purifier itself works great and the water tastes amazing. We are no longer afraid of waterborne sickness.”
A survey tells you about use and satisfaction, not health outcomes, and we say so in our reports. For the filter itself, here is the Shriram Institute test report (PDF).
For CSR teams: making safe drinking water available is listed under Schedule VII of the Companies Act, and we can deliver in your operating districts. For government buyers and the armed forces: Jal Kavach is listed on the Government e-Marketplace (GeM), product ID 5116877-6200555098.
DetoXyFi began in Professor Rohit Karnik’s lab at MIT, where a team spent more than a decade looking for low-cost ways to make water safe to drink. The work was published in Nature Communications and field-tested with families in India, Uganda, Madagascar and the United States.
We brought that know-how home and built Jal Kavach for Indian water, Indian taps and Indian budgets. It is made in India. Our goal is the one painted on Jal Jeevan Mission boards across the country, har ghar jal, water in every home. We want that water to be safe to drink.
For your own kitchen, or a bottle for the train. The tap filter is on Amazon and Blinkit; the bottle filter you can order from us directly.
Clamps onto most Indian taps, including plain bib-cocks, in two minutes. No plumber, no tools.
Not sure it fits? WhatsApp us a photo of your tap.
From ₹749 ₹749 on Blinkit, ₹849 on Amazon. MRP ₹1,299
34 grams. Screws onto a regular water or soft-drink bottle, for safe water on a trek, a train or a long day out.
Out of stock on Amazon right now. Order direct and we’ll ship it.
The tap filter fits most standard Indian taps using the adjustable metal clamp and adaptor in the box. For programmes, we check the taps at your sites before rollout. For your own home, send a photo of your tap on WhatsApp (+91 73030 95923) and we’ll tell you.
The bottle filter works anywhere water can be poured into a bottle, including hand pumps, wells and stored water. We can help you choose the right mix for your sites.
It depends on how much water a family uses and how muddy it is. For most families it lasts several months. When the flow slows noticeably, it’s time to replace it.
Yes. In the Assam villages where we work, families filter water from muddy river channels with it, and our field video shows pond water coming out clear. Mud does make the flow slow down sooner. If you can, let a bucket stand for a while so the mud settles, then filter the clearer water from the top. The filter will last longer.
No. Jal Kavach keeps natural minerals and does not remove dissolved salts or heavy metals. It’s built to make germ-contaminated water safe, which is the most common problem in rural and low-income urban water.
Flush it for 10 seconds before first use. Use cold or room-temperature water, never hot, and don’t let it freeze. Wipe the outside with a soft cloth.
Yes, 6 months against manufacturing defects.
Making safe drinking water available is listed in Schedule VII, item (i), of the Companies Act, alongside preventive health care and sanitation. Your CSR committee decides how to classify a project; we provide the records.
Both. Jal Kavach is listed on the Government e-Marketplace, product ID 5116877-6200555098. For direct orders we issue a GST invoice (18% GST) from DetoXyFi Technologies Pvt. Ltd., GSTIN 09AAJCD8722E1ZJ, and can fill in your vendor registration forms.
Distribution records against each household, school or health centre, photographs from the distribution, and the results of a family feedback survey. For the filter itself, the Shriram Institute lab report.
Hi,
I’m Dhananjay. I run DetoXyFi with Rohit and a small team in India.
Most of our work happens far from this website. In school courtyards in Visakhapatnam. In river villages in Dhubri. At the local hospital in Kotma.
The filter is small, and the idea is simple: the tap a family already has should give water they can drink without worrying.
We don’t get everything right. Some water needs more than our filter can do, and when it does, we say so.
If you work with communities like these, write to me. I read every email myself.
Dhananjay