Solar electrodialysis units that make salty village groundwater drinkable
TL;DR Saltfree builds solar-powered electrodialysis units for villages whose borewells give salty water. They recover most of the water they draw, so far less of it ends up as brine. State water departments and CSR funds pay for the plant and its upkeep, and households buy water by the can.
Salty groundwater is a quiet problem in India but a very widespread one. US university researchers estimated that about 60% of the country sits over salty aquifers, and much of that land has no grid strong enough to run reverse-osmosis plants[1]. Most rural Indians drink water above 1,200 ppm of dissolved salts, double the WHO's suggested ceiling[2].
The usual fix wastes water. Jal Jeevan Mission's own guidelines say a village RO plant rejects around 60% of what it pumps, and that this brine often ends up in a drain or a pool by the plant[3]. Does it make sense to pump two litres from a falling water table to deliver less than one? Not in a dry district, it doesn't.
What it does, in regulatory terms: community drinking-water treatment to BIS IS 10500 limits. It makes no health claims, and each site's output is tested by an accredited lab.
Saltfree installs a container-sized unit beside an existing borewell. Solar panels drive an electrodialysis-reversal stack, which pulls salt ions out through membranes instead of forcing water through them at high pressure. The control system varies pumping and stack voltage with the sunlight, so the unit needs only a small battery, and a cellular link reports flow, salinity and faults to a central desk. A local operator sells cans and handles cleaning, while Saltfree's technicians look after the stack.
The seed pitched solar desalination in general, which usually means seawater, so I'd reframe it. India's nearer problem is inland water at 500–3,000 mg/L of salt, where electrodialysis uses less energy than RO and recovers more than 90% of the feed water[1]. That's the market Saltfree goes after first.
Villagers drink the water, but the plant is usually bought by someone else. Under Jal Jeevan Mission, states may fund community purification plants as a stopgap where groundwater is unsafe, and coastal areas are told to prefer small, energy-efficient desalination with high recovery[3]. CSR foundations already fund water-station networks[4]. Households then pay per can. I found no published standard price, so the sprint has to establish one.
Battery cost used to be the big barrier to off-grid electrodialysis. In 2023, a US university team showed that varying the stack with the sun cut battery needs by 92% and made solar electrodialysis cost-competitive with grid-connected village RO in an Indian case study[5]. Battery packs then fell 20% in 2024 to US$115/kWh, about ₹11,100[6]. The JJM guidelines also put brine handling on every RO operator's checklist[3].
There's no public figure for an Indian brackish-water desalination market. The demand for paid community water stations is better documented. One water-ATM operator reported over 7.65 lakh people served daily from 1,965 touch points in 20 states[4], and one water nonprofit reaches 1.3 million people through 346 communities[7]. Treat these as adjacent though - both mostly run RO, and not every site is salty.
Water-ATM operators and water nonprofits run remotely monitored RO water stations with local operators[4][7]. A US university lab and an Indian irrigation company built and field-tested a solar electrodialysis prototype with UV disinfection in Indian villages[2]. What I did not find is an Indian operator that deploys high-recovery solar electrodialysis as a paid service across many villages. That is the gap.
| Difficulty | Hard (61/100) |
| Starting capital | ₹2.8–4.7 Cr |
| Time to launch | 12–18 months |
The chemistry is known. The hard part is making a membrane stack survive two years of village use with a part-time operator, and keeping service visits cheap across scattered sites. Selling is slow too. Government buyers tender on purchase price, so you have to win on cost per litre over five years, which is a number PHED engineers rarely get to see.
Yes, this is regulated. You're treating drinking water for villages, so standards and local consents apply before a single can is sold.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Never let AI decide whether water is safe to drink. That call comes from accredited lab tests, not a sensor model.
Want to work out the AI layer for Saltfree? Talk to Yash →
I'd back an engineer-founder with water-treatment or rural-operations experience who can live with government sales cycles. If you're hoping for a quick consumer product then it is a poor fit. Before you raise money, prove that one unit in a salty village delivers safe water for six months at a cost per litre close to RO's, with brine below 15% of intake.
Plan for roughly ₹2.8–4.7 Cr, covering stack development, field pilots and the slow government sales cycle.
It can be, but only if you win on cost per litre over several years. Most tenders favour the cheapest RO plant, so prove your lifetime cost in a pilot first.
Yes, salty inland groundwater is common in many dry regions. Check your local drinking water standard and who funds rural water before you build.
The free Saltfree validation kit has the line-by-line capital breakdown, the effort scoring, the drinking-water and tender checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for water departments and village operators, and 5 assumptions to test. Download the kit →
Thinking about building Saltfree or something close to it? The make-or-break bit is keeping a membrane stack running in a remote village and getting a water department to pay for lifetime cost rather than sticker price, and that's the kind of thing I help founders with. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.