New Water Purification Technology Turns Seawater Into Drinking Water With Fewer Chemicals: What It Is and What It Could Mean for Pakistan
In early 2025 American engineers described carbon-cloth electrodes that strip boron from seawater without the acids and alkalis desalination plants normally use. This plain-English guide explains the discovery, what it does and does not do, and why a thirsty coastal country like Pakistan should pay attention.
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⚡ The short answer
Turning seawater into drinking water means removing salt, which is done by forcing the water through a very fine membrane. But one natural ingredient of seawater, boron, slips through. Getting it out normally takes an extra stage and large amounts of acid and alkali. In January 2025 engineers at two American universities reported a way round that: electrodes made of carbon cloth that capture boron using electricity alone. They estimate it could cut the cost of desalination by up to 15 per cent. It is a laboratory result, not yet a factory product, and it deals with one step, not the whole process. For countries short of fresh water, Pakistan among them, even one cheaper step matters.
- ✅ Who: University of Michigan and Rice University, in the journal Nature Water
- ✅ What: carbon-cloth electrodes that remove boron without added chemicals
- ⚠️ Not chemical-free: salt is still removed by reverse osmosis first
- ⚠️ Stage: laboratory; no commercial plant found
The problem it solves
How seawater is made drinkable
About 35 grams of salt, roughly two tablespoons, are dissolved in every litre of seawater. The modern way to get it out is reverse osmosis.
- Seawater is drawn in and filtered to remove sand, weed and living things.
- High-pressure pumps push it against a membrane, a plastic sheet with pores so fine that water molecules pass but dissolved salts do not.
- Fresh water comes out one side. Very salty water, called brine, is left on the other and returned to the sea.
- The fresh water is treated to make it safe and pleasant to drink.
The membrane works because salt in water splits into electrically charged particles. The membrane repels them.
The ingredient that gets through
Seawater also contains boron, a natural element. In seawater it exists as boric acid, which carries no electric charge. The membrane does not repel it, and the molecule is small. A good share of it passes straight through.
That matters for two reasons.
| Boron in seawater compared with the safe level | |
|---|---|
| For drinking | About twice the World Health Organization’s most lenient limit |
| For crops | Five to twelve times what many plants can tolerate |
A little boron is harmless and plants need a trace of it. Too much, over time, is bad for people and quickly damaging to crops such as citrus, which is why countries that irrigate with desalinated water set strict limits.
The usual fix
Desalination plants solve the problem with chemistry.
- They add an alkali (a base) to the water that has already been through the membrane. This raises its pH and turns boric acid into a charged form.
- They run the water through a second set of membranes, which now catches the boron.
- They add acid to bring the water back to neutral.
It works. It also means buying, shipping and storing large quantities of caustic chemicals, running more pumps and more membranes, and disposing of more waste.
The first pass through the membrane removes ninety-nine per cent of what is wrong with seawater. A surprising share of the cost goes on the last stubborn fraction.
The new idea
Carbon cloth
The researchers used a material called carbon cloth: a fabric woven from carbon fibres, of the kind already used in fuel cells. It conducts electricity and has an enormous surface area for its size.
They treated the cloth so that its surface carries chemical groups, containing oxygen, that are good at grabbing boron.
How the device works
Two sheets of the cloth act as electrodes, one positive and one negative, with water flowing between.
- At one electrode, electricity splits a little water into its charged parts. One of these is the hydroxide ion, the same thing an added alkali would supply.
- Hydroxide attaches to boric acid and gives it a negative charge.
- The now-charged boron is drawn to the positive electrode and held on its surface.
- Clean water flows on.
- When the cloth is full, the process is reversed and the boron is flushed away.
In effect, the device makes its own alkali on the spot, uses it, and unmakes it, with nothing added but electricity.
| Conventional method | Carbon-cloth electrodes | |
|---|---|---|
| Alkali added | Yes | No; made inside the device |
| Second membrane stage | Yes | Not needed for boron |
| Acid added afterwards | Yes | No |
| Energy | High-pressure pumps for the second stage | Low-voltage electricity |
| Proven at scale | Yes, worldwide | Not yet |
What the researchers claim
- A saving of up to 15 per cent of the cost of desalination, about 20 American cents for every cubic metre.
- Across all the world’s plants, savings in the billions of dollars a year.
- A process that can be scaled up and that uses less energy than the alternatives.
These are the inventors’ own estimates, made from laboratory tests.
💡 Tip: how to read a “breakthrough” headline
Science news loves the word breakthrough. Four questions bring it down to earth. Where was it done? A laboratory bench is not a factory. Who says it works? The inventors, or someone independent? Compared with what? A 15 per cent saving on one step is not a 15 per cent cut in your water bill. How long until it is used? For water technology the gap between a paper and a working plant is usually ten years or more, and most ideas never cross it. None of this makes the research less clever. It makes the headline more honest.
What it does not do
The original headline said seawater could be made drinkable “without harsh chemicals”. That goes too far.
- Salt is still removed by reverse osmosis. The electrodes deal with boron only, after the main stage.
- Other chemicals are still used: to clean membranes, prevent scale, disinfect the water and adjust its taste.
- It has not been tested in the sea. Real seawater fouls every surface it touches. How long the cloth lasts, and how often it must be cleaned, is unknown.
- No plant has been built. A search in October 2026 found no report of a pilot project or a commercial licence.
A fairer summary is the one the engineering press used: fewer chemicals, at one stage, in the laboratory.
⚠️ A promising result is not a product
Nothing in this article means that cheaper desalinated water is about to arrive, in Pakistan or anywhere. The method may fail when scaled up, may prove more expensive than hoped, or may be overtaken by a better membrane that blocks boron in the first place, which several groups are also working on. Public money should not be planned around a laboratory paper.
Why it matters to Pakistan
A country short of water
Pakistan is among the most water-stressed countries in the world. The amount of fresh water available for each person has fallen to roughly a fifth of what it was at independence, mainly because the population has grown more than sixfold while the rivers have not.
Almost all of that water comes from one river system, the Indus, and almost all of it goes to farming.
Karachi
The sharpest shortage is in Karachi, a city of twenty million or more on the Arabian Sea.
- The city receives perhaps half the water it needs, piped more than a hundred kilometres from the Indus and from a reservoir to the west.
- A large share is lost to leaks and theft.
- Much of the rest reaches homes by tanker, at many times the piped price.
- The sea is at the city’s doorstep.
Desalination has been proposed for Karachi many times. A few small plants have been built. The largest schemes have stalled on cost, on electricity supply and on arguments over who would pay.
The coast of Balochistan
Gwadar, the port at the centre of the Chinese-financed economic corridor, has almost no fresh water of its own. A desalination plant was built there with Chinese help and others were built earlier and fell out of use. Residents’ protests over water have been a regular feature of the town’s politics.
Inland: a different salt problem
Much of the groundwater under Sindh and southern Punjab is brackish: too salty to drink, though far less salty than the sea. In the desert district of Tharparkar the provincial government installed hundreds of small solar-powered reverse-osmosis plants. Many broke down for want of maintenance. It is a reminder that the technology is the easy part.
Would this discovery help?
| Question | Honest answer |
|---|---|
| Would it make a Karachi desalination plant cheaper? | A little, if it works at scale; boron removal is one cost among many |
| Does Pakistan need it for irrigation? | Not yet; Pakistan does not irrigate with desalinated seawater |
| Is boron Pakistan’s main water-quality problem? | No. Bacteria from sewage, and arsenic and fluoride in groundwater, are far more serious |
| What is the real obstacle to desalination in Pakistan? | Electricity cost, maintenance and financing |
So the direct benefit to Pakistan would be modest. The indirect benefit is larger. Every improvement that lowers the world price of desalinated water brings the day closer when a coastal city can afford to drink from the sea.
Who desalinates, and how much
Desalination is no longer exotic. It is how a large part of the world drinks.
| Country or region | How much it relies on the sea |
|---|---|
| Saudi Arabia | The world’s largest producer; about half of its drinking water |
| United Arab Emirates, Kuwait, Qatar, Bahrain | Most of their drinking water |
| Israel | Well over half of household water |
| Singapore | A growing share, alongside recycled water |
| Spain, Australia, California | Large plants built as insurance against drought |
| China and India | Rapidly growing capacity on their coasts |
| Pakistan | A handful of small plants |
There are more than twenty thousand desalination plants in the world, producing enough each day to supply several hundred million people.
Two lessons from the countries that depend on it are relevant to Pakistan.
It works when it is run as a utility. The Gulf states and Israel treat desalination as essential infrastructure, with professional operators, guaranteed electricity and a tariff that covers the cost. The plants run for decades.
It fails when it is run as a project. Pakistan’s small plants were mostly built with a grant or a one-off budget, opened with a ceremony and then left without money for membranes, chemicals, power or trained staff. Several were shut within a few years. The technology was never the problem.
Other ways to find water
Desalination is the most expensive answer to a water shortage. Engineers generally say it should be the last one tried, after cheaper measures.
| Measure | What it involves | Cost compared with desalination |
|---|---|---|
| Fixing leaks | A third or more of Karachi’s piped water is lost before it reaches a tap | Far cheaper |
| Stopping theft | Illegal hydrants divert public water to tankers | A matter of enforcement |
| Metering and fair pricing | People who pay by volume waste less | Cheap |
| Recycling wastewater | Treated sewage can be used by industry and for watering | Cheaper |
| Harvesting rain | Storing monsoon run-off in tanks and recharge wells | Cheap, but seasonal |
| Saving water on farms | Lining canals; drip irrigation; changing crops | The largest saving available anywhere in the country |
| Desalination | Making new fresh water from the sea | The most expensive |
More than nine-tenths of Pakistan’s water goes to agriculture, much of it to flood fields of rice and sugar cane. A saving of a few per cent there would release more water than every desalination plant the country could afford to build.
That is the context in which any new desalination technology should be read. Making seawater a little cheaper to treat is welcome. For Pakistan the bigger gains lie in not wasting the fresh water it already has.
What desalination costs
A rough guide, in American cents per cubic metre (1,000 litres).
| Source of water | Typical cost |
|---|---|
| River water, treated and piped | 10 to 30 |
| Brackish groundwater, desalinated | 30 to 60 |
| Seawater, large modern plant | 50 to 100 |
| Seawater, small or old plant | 150 or more |
| Water delivered by tanker in Karachi | Several hundred |
Two things stand out. Desalinated seawater costs several times what river water does. And it costs far less than the tankers on which millions of Karachi’s residents already depend. The city’s poor are, in effect, already paying desalination prices for water of worse quality.
About half the cost of desalination is electricity. That is why the Gulf states, with cheap energy, lead the world in it, and why Pakistan’s expensive and unreliable power is the heart of its problem. It is also why the collapse in the price of solar panels may matter more to Pakistan’s water future than any improvement in membranes.
The other side: brine
Desalination has an environmental cost. For every litre of fresh water, a plant returns about a litre and a half of brine to the sea: water roughly twice as salty as normal, warmer, and carrying traces of the cleaning chemicals.
Poured into shallow or enclosed waters, it can harm fish, coral and the plants of the seabed. Good practice is to dilute it and release it through long pipes into deep, moving water.
Using fewer chemicals, as the new method promises, would make the brine a little cleaner. It would not make it less salty.
At home: what filters do
Many Pakistani households already own a small reverse-osmosis unit under the kitchen sink. A few plain points.
| Type of filter | Removes | Does not remove |
|---|---|---|
| Boiling | Bacteria and viruses | Salt, arsenic, chemicals |
| Ceramic or cloth filter | Dirt, many bacteria | Viruses, salt, chemicals |
| Activated carbon | Chlorine taste, some chemicals | Salt, most germs |
| Ultraviolet lamp | Germs | Salt, dirt, chemicals |
| Household reverse osmosis | Salt, arsenic, most contaminants | Works only if membranes are changed on time |
- For most Pakistani tap water the main danger is germs from sewage. Boiling deals with that.
- A reverse-osmosis unit is worth having where water is salty or where arsenic or fluoride is known to be present.
- An unmaintained filter can be worse than none.
✅ Key point
The research reported in January 2025 is a neat piece of engineering: it replaces lorry-loads of acid and alkali with a piece of cloth and a little electricity. It will not, by itself, end anyone’s water shortage. Pakistan’s water crisis is not waiting for a new invention. It is waiting for pipes that do not leak, plants that are maintained, electricity that is affordable and a price for water that pays for all three.
Words used in this article
| Term | Plain meaning |
|---|---|
| Desalination | Removing salt from water |
| Reverse osmosis | Forcing water through a membrane that holds back dissolved salts |
| Membrane | A very fine filter, usually a plastic sheet |
| Brine | The very salty water left over after desalination |
| Boron | A natural element found in seawater |
| Boric acid | The form boron takes in seawater; it has no electric charge |
| Ion | An atom or molecule carrying an electric charge |
| Electrode | A conductor through which electricity enters or leaves a liquid |
| Alkali, base | The chemical opposite of an acid |
| Brackish water | Water saltier than fresh water but less salty than the sea |
| Cubic metre | One thousand litres |
What to watch next
- A pilot plant testing the electrodes on real seawater.
- Rival methods, especially membranes designed to block boron directly.
- Karachi’s long-promised large desalination projects.
- The price of solar power, which matters more than any single invention.
For who is responsible for water in Pakistan, which is mostly the provinces and the cities, read our guide to Pakistan’s politics.
Understand who is responsible for what
PoliticsPK explains who is who, how the system works and what changes, without the noise.
More in Politics Explained Politics Explained Latest from PoliticsPK
Frequently asked questions
❓ What is the new water purification technology?
Electrodes made of carbon cloth that remove boron from desalinated seawater using electricity, without the acid and alkali that plants normally add. It was reported in January 2025 by engineers at the University of Michigan and Rice University.
❓ Does it turn seawater into drinking water without chemicals?
Not entirely. Salt is still removed by reverse osmosis, and other treatment chemicals are still used. The method avoids chemicals at the boron-removal stage.
❓ Why is boron a problem?
It is naturally present in seawater, passes through desalination membranes, and at high levels is harmful to people over time and damaging to many crops.
❓ How much money could it save?
The researchers estimate up to 15 per cent of the cost of desalination, about 20 US cents per cubic metre. This has not been confirmed at commercial scale.
❓ Is the technology in use?
No report of a commercial or pilot plant was found when this article was written. It remains a laboratory result.
❓ Does Pakistan have desalination plants?
A few small ones, in Karachi, at Gwadar and elsewhere, along with many small plants treating brackish groundwater. Large-scale seawater desalination has been proposed but not built.
❓ Why does Karachi not simply desalinate seawater?
Cost, electricity supply and financing. Desalinated water costs several times what river water does, though less than water delivered by tanker.
❓ What is reverse osmosis?
A process in which water is pushed at high pressure through a membrane fine enough to hold back dissolved salts.
❓ Is a home reverse-osmosis filter necessary?
It is useful where water is salty or contains arsenic or fluoride. For water contaminated mainly by germs, boiling is effective. Any filter must be maintained.
Sources
- University of Michigan alumni news, “New water purification technology helps turn seawater into drinking water without tons of chemicals” — January 2025.
- Environmental News Network, the same release — January 2025.
- American Institute of Chemical Engineers, “Carbon Cloth Electrodes Could Reduce the Cost of Seawater Desalination” — March 2025.
- Chemical Engineering, “Carbon cloth electrodes bring new possibilities to seawater desalination” — 2025.
- Engineers Ireland, “US engineers make seawater drinkable via new cheap process” — 2025.
- Nature Water — the journal in which the study appeared; the paper itself was not read.
- World Health Organization, drinking-water guidelines — for the limit on boron.
