A claim that did not survive a real comparison
Direct lithium extraction is usually described as the water saving alternative to evaporation ponds, the older method used across salt flats in South America. Evaporation ponds pump brine, salty water drawn from underground, into shallow pools and let the sun evaporate the water for a year or more before filtering out the lithium left behind. Direct lithium extraction instead runs the brine through a chemical process inside a plant while it is still liquid. A 2025 study in the peer reviewed journal Heliyon tested the water saving claim against 2 real plants in Argentina rather than a general estimate. Walter Fernando Diaz Paz and 7 coauthors compared environmental impact reports filed by each plant with the Argentine government for the same production year, 2021, and measured the freshwater footprint of each one, the volume of freshwater a plant draws from a source that does not return to it, for every ton of battery grade lithium carbonate produced, the refined lithium compound battery makers buy.
What the comparison found
Fenix, the direct extraction plant in the study, used 135.5 cubic meters of freshwater for every ton of lithium carbonate it produced in 2021. Olaroz, the evaporation pond compared against it, used 51.0 cubic meters for the same ton, less than half as much. Fenix used 2.7 times more freshwater per ton than Olaroz, the ratio the study itself reports.
The 2 plants are compared using environmental impact reports filed by each one for the same production year, 2021, not a general industry estimate.
Show the numbers
| Olaroz, evaporation pond | 51.0 |
| Fenix, direct extraction | 135.5 |
The study traces the gap to the chemistry of the brine at each site, not to direct extraction being a thirstier technology overall. The brine Fenix draws from, at the Hombre Muerto salt flat, carries less sulfate and more sodium and magnesium than the brine at Olaroz, and reaching battery grade purity from that mix needs more washing and polishing steps, each one using freshwater. The comparison covers only these 2 named plants.
The trade the fuller picture shows
Freshwater is not the only water these plants draw. Both also pull far larger volumes of brine itself out of the ground to isolate the lithium, and there the ranking reverses. Olaroz drew 537.4 cubic meters of brine for every ton produced, against 319.6 cubic meters at Fenix, about 68% more brine at Olaroz than at Fenix, a figure calculated from the 2 numbers the study reports rather than stated by the study directly.
Brine is the salty underground water lithium is dissolved in, a separate measure from the freshwater figure shown above.
Show the numbers
| Olaroz, evaporation pond | 537.4 |
| Fenix, direct extraction | 319.6 |
So the full comparison is a trade rather than a win for either method. Fenix drew more freshwater from local supplies, while Olaroz drew more brine from the reservoir underneath the salt flat.
A different plant tried recycling instead
Eramet, a separate mining company, runs a different direct extraction plant, Centenario Ratones, on a different Argentine salt flat from the one Fenix and Olaroz sit on. Eramet reports recycling 60% of its own process water there, and reaching battery grade lithium carbonate in under 1 week, against the 18 months evaporation ponds need for the same step. That is a separate plant, measured by a different method, a recycling percentage rather than freshwater drawn per ton, and it does not confirm or explain what the Heliyon study found at Fenix and Olaroz.
What the study concludes
The study puts it directly.
Our results indicate that freshwater availability is more of a constraint to DLE projects than conventional evaporation technologies.
Walter Fernando Diaz Paz and 7 coauthors, authors of the study, working with the national science council of Argentina. Source 1.