From Freshwater to Seawater: Water Demand in Chilean Copper Mining Outlook

Water is a vital input for Chile’s mining industry, essential to every stage of copper production—from ore processing to dust control. As water scarcity deepens across northern Chile, the country’s copper mining sector is undergoing a structural transformation in how it sources and uses water. According to the latest report from Cochilco, the demand for water in copper mining is projected to grow from 18.8 m³/s in 2023 to 22.1 m³/s in 2034, a 17.6% increase—driven not by expansion alone, but by the need to process lower-grade sulfide ores that require more intensive water usage. This is not just an operational issue—it marks a strategic shift in how the sector must source, manage, and invest in water for long-term viability.

Key Water Demand Trends in Chilean Copper Mining (2024–2034)

Chile’s copper mining industry is entering a transformative period in how it sources and consumes water. According to recent projections, total water demand across the sector is expected to grow from 18.8 m³/s in 2023 to 22.1 m³/s by 2034, representing a 17.6% increase over the decade. This reflects an average annual growth rate of 1.5%, largely driven by the shift to lower-grade sulfide ores that require more water-intensive flotation processes. Water demand is projected to peak in 2031 at 22.2 m³/s, then remain relatively stable through 2034.

Shifting Water Sources: From Freshwater to Seawater – A defining trend in this period is the dramatic shift in water sourcing. Continental (fresh) water use is projected to decline sharply, from 12.0 m³/s in 2023 to 7.6 m³/s in 2034, a 36.7% reduction. In contrast, seawater use is forecasted to more than double, rising from 6.8 m³/s to 14.5 m³/s—an increase of 113.2%. By 2034, an estimated 66% of total water used in copper mining will come from the sea, underscoring a profound move toward sustainable, non-continental water sources, particularly desalinated seawater.

Water Use Grows Faster than Copper Output – From 2023 to 2029, water consumption and copper production are projected to increase in parallel. However, between 2029 and 2034, water use continues to grow even as copper output levels off. This decoupling is attributed to several factors: lower ore grades that require processing more material per tonne of copper, increased complexity in ore processing, and a reduction in hydrometallurgical methods—which typically use less water.

Water Demand by Project Status – By 2034, the breakdown of total mining water demand by project stage is expected to be as follows:

• 58.7% from projects in operation
• 20.1% from projects at the feasibility stage
• 14.7% from projects under execution
• 6.5% from pre-feasibility projects

This shows that new and existing projects are increasingly designed with seawater supply in mind, reflecting regulatory, environmental, and community expectations for responsible water use.

Freshwater Use Declines Sharply in Active Mines – Among operational projects, freshwater use is expected to decline by 50%, from 11.0 m³/s in 2023 to 5.5 m³/s in 2034. This drop is largely attributed to new desalination capacity—notably from projects like Los Pelambres (AMSA) and Mantoverde (Capstone). Projects in the feasibility and pre-feasibility stages are now being designed with seawater use as a foundational element, ensuring water resilience and long-term viability.

Water Demand by Mining Process – By 2034, 77% of total mining water demand (approximately 17.0 m³/s) will be consumed by concentration processes, which are particularly water-intensive. Around 70% of that volume will be seawater.
Other processes include:

• Hidrometallurgy, accounting for 7% of total water use, with 44% sourced from seawater
• Smelting and refining, which will see a 37% increase in water demand, partly due to the new Paipote smelter, which plans to utilize seawater

Desalination Plants in Operation (as of 2024) – Chile’s copper mining industry has made major strides in shifting toward seawater use, backed by a growing network of desalination plants, especially in northern regions. These facilities vary in scale and complexity but are critical to reducing dependence on scarce freshwater sources.

Notable operational plants include:

• Escondida (BHP) – the largest, with a capacity of 2,500 l/s
• Candelaria (Lundin Mining) – 500 l/s
• Los Pelambres INCO (AMSA) and Mantoverde (Capstone) – newly operational as of 2023–2024
• Other key sites: Spence, Antucoya, Quebrada Blanca, and Sierra Gorda

Many plants involve extensive infrastructure, including pipelines stretching up to 180 km, emphasizing the high capital intensity of transporting seawater inland.

Pipeline of Upcoming and Proposed Projects (2024–2033) – The report outlines a robust pipeline of future and hypothetical desalination projects, expected to significantly increase national capacity by 2033. These are concentrated in Atacama, Antofagasta, Coquimbo, Valparaíso, and Tarapacá.

Key upcoming projects:

• Codelco Distrito Norte – 1,956 l/s (Antofagasta)
• Nueva Unión (Teck/Goldcorp) – 700 l/s (Atacama)
• Collahuasi C20+ – 1,050 l/s (Tarapacá)
• Vizcachitas (Valparaíso) and Aguas del Pacífico – 1,000 l/s (multi-client shared use)

Strategic Trends and Constraints in Mining Desalination – As seawater becomes a key resource for Chile’s copper mining sector, a clear strategic shift is emerging: the move toward shared desalination infrastructure. Projects like Aguas del Pacífico exemplify this trend, allowing multiple mining operations to benefit from a single desalination and pipeline system—reducing both capital costs and environmental impact. However, the rollout of desalination is still constrained by geographical and technical challenges, particularly for inland or high-altitude operations, where pumping distances and energy costs make seawater less feasible. As a result, while desalination is increasingly integral to future project planning, site-specific conditions continue to shape how and where it can be deployed.

Conclusion: A New Water Era for Chilean Mining

Chile’s mining industry is leading the global shift toward sustainable water use by rapidly adopting desalinated and seawater sources. By 2034, 66% of mining water is projected to come from the sea, driven by both climate pressures and a commitment to long-term operational viability.

Yet this transformation goes beyond infrastructure. To ensure true sustainability, the industry must invest in technologies that reduce consumption, enable recirculation, and lower the energy costs associated with desalination. Shared infrastructure, like multi-client desalination plants, is gaining traction as a cost-effective and environmentally smarter model.

Still, not all mining operations can make the switch—geographic and technical barriers, especially for inland or high-altitude projects, remain a challenge. That’s why a coordinated approach is essential: combining energy and water efficiency, regulatory reform, and early community engagement.

Chile is laying the groundwork to become a global benchmark in sustainable mining. The next decade will be shaped by how effectively it balances water security, environmental responsibility, and competitiveness.

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