Chilean Copper Mining Water Use: What the 2025 Cochilco Report Shows

Water is a critical and irreplaceable input for Chile’s mining industry, underpinning every stage of copper production, from complex sulphide ore processing and tailings management to dust control in open pits. As scarcity intensifies across northern Chile, the sector is experiencing a profound structural shift in how it sources, manages, and accounts for this resource.

Each year Cochilco publishes its Water Survey for Chilean copper mining, giving stakeholders a clear, data-based view of where water is used and how companies secure supply through continental rights, seawater, desalination, and large-scale recirculation systems. The latest report analyses 49 operations that represent almost the entire national output, and remains the principal public benchmark on the industry’s water footprint within an increasingly dry territory.

For foreign technology and industrial service companies, these figures are more than sustainability indicators. They shape product adoption, investment priorities, and permitting strategies for solutions that reduce withdrawals or improve reuse, in an industry that is actively seeking to decouple growth from freshwater dependency.

Extraction vs. Real Consumption

The first question the 2025 numbers raise is why water extraction increased much faster than effective consumption.

• Net water consumption reached 18.13 m³/s in 2024, up 2.7 percent from 2023.
• Copper production in the same period grew 4.8 percent, which means unit intensity fell slightly.
• Operational water extraction climbed to 22.74 m³/s, a 20.8 percent rise, but Cochilco explains that this is largely due to methodology changes aligned with ICMM guidance.
• The new framework counts rainfall and surface inflows entering the mining system even when they are not diverted permanently.
• This accounting effect represented about 2.7 m³/s of the reported increase; excluding it, the real variation would have been closer to 6.3 percent.

Understanding this distinction is essential when teams communicate performance to investors or regulators.

Where Water Is Actually Used

Water behaviour differs sharply by process and the 2025 report breaks this down clearly:

• Concentration and tailings deposition consumed 14.56 m³/s, equivalent to 80.3 percent of all mining water use.
• Hydrometallurgical circuits used 1.53 m³/s (8.4 percent) and fell compared with 2023 because fewer oxide operations remain active.
• Dust control accounted for 1.11 m³/s (6.1 percent).
• Mine services, camps, and other minor uses represented the balance.

The growth in concentrators reflects two structural facts: ore grades continue to decline and the industry is processing a larger share of sulphide ore, which requires more intensive grinding, flotation, thickening, and filtration per tonne of metal.

Seawater Moves Centre Stage

The long-term shift from freshwater to seawater remains one of the clearest stories of the year:

• Seawater extraction reached 7.80 m³/s in 2024, increasing 14.7 percent over 2023.
• Seawater now represents 9.9 percent of total water use, compared with 3.7 percent in 2014 — almost triple in a decade.
• Fuel and electricity extraction for desalination infrastructure continues to expand to support this transition.

This confirms that the industry is gradually decoupling growth from inland basins and relying more on desalination plants, pipelines, and highly engineered circulation systems.

Recycling as the Main Defence

Once water enters the mining system, most of it continues to be reused:

• Reused and recirculated water supplied 55.75 m³/s, up 2.9 percent from 2023.
• This volume is three times larger than freshly consumed water, showing the importance of tailings facilities, evaporation control, and filtration plants.

However, higher reliance on recycling sets a high bar: any failure in relaves or circulation infrastructure immediately affects the operations.

Regional Patterns Define Risk

Geography still explains most of the sensitivity:

• Antofagasta led extraction at 10.69 m³/s, and 58 percent of that was seawater, reflecting strong adoption of alternative supply.
• Atacama recorded its sixth consecutive year of reduced continental water extraction, the lowest level of the past decade, even while copper output rose.
• Valparaíso, O’Higgins, and the Metropolitan Region depend only on continental sources.
• Coquimbo and Tarapacá began using seawater in 2023 and showed moderate increases in 2024.

For companies planning expansion, water strategy must be managed by regions rather than by national averages.

Opportunties for Mining Suppliers

• The rising share of sulphide processing means concentrator efficiency is the largest lever to reduce water intensity.
• Technologies that lower evaporation losses, improve tailings filtration, and optimize desalination pumping will capture the biggest payoff.
• Measurement definitions now matter as much as physical use; consistent baselines are critical for accounting and intercompany alignment.
• Structures that reduce continental extraction are already helping companies advance projects with lower social and permitting risk, particularly in northern regions.

Final Thought

The 2025 Cochilco update reminds us of something the industry has learned the hard way: water in Chilean copper mining is not just another input, it is part of a much bigger operating system. Extraction totals may rise or fall on paper as definitions evolve, but the real direction is clear , companies are relying more on seawater and reuse inside their own plants to keep production stable in one of the driest parts of the country.

Chile’s rapid move toward desalinated and marine sources shows how climate pressure and economics are starting to point to the same answer: protect inland water while still supporting copper growth. The forecast that about 66 percent of mining water could come from the sea by 2034 is a strong signal of that change, but it also highlights the next challenge,  how to reduce consumption first, especially in concentrators and tailings where most demand is generated.

The good news is that technology is beginning to catch up. Solutions that improve recirculation, evaporation control, and pumping efficiency are being received by operators that want lower withdrawals and lower energy costs at the same time. The idea of shared desalination infrastructure for several users is another encouraging trend because it spreads impact and makes projects more competitive.

Not every operation can switch easily, particularly inland or high-altitude projects, so regulation, measurement and early community engagement still matter as much as engineering. What Cochilco’s numbers ultimately show is an industry trying to become more practical about water: use it better, reuse it longer, and be transparent about the footprint.

Chile is turning into a real benchmark for how large copper mining can operate with fewer freshwater basins. The next decade will be defined by how well companies, advisors and foreign innovators stay aligned on that goal , balancing water security, environmental responsibility and competitiveness, without losing sight of the people who live next to the mines.

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