The year 2024 was marked by extreme weather events, which were increasingly frequent and intense. For the first time, the global average temperature exceeded 1.5°C compared to the pre-industrial period, and 2025 promises to be among the three warmest years on record (C3S, 2024). Climate change intensifies the challenges related to water scarcity, causing severe droughts, changes in precipitation patterns, melting glaciers, and reduced snow cover in mountain ranges. Less than 3% of the world’s water is fresh (drinkable), of which 2.5% is frozen in the Arctic, Antarctic, and glaciers. Thus, humanity must rely on only 0.5% for all the fresh water needs of humanity and ecosystems (UN-Water, 2021). This scenario highlights the need for effective tools for sustainable water management.

The water footprint is an essential metric for quantifying the impact of water use in production processes and throughout the value chain (Hoekstra, 2003), which is divided into three categories: blue water (surface or groundwater), green water (from rain and stored in the soil, used by plants), and gray water (volume needed to dilute pollutants and meet quality standards). When integrated into Life Cycle Assessment (LCA), this analysis becomes even more robust, as it considers not only direct and indirect water consumption, but also its regional availability and impacts on biodiversity.

Aquaculture emerges as a more sustainable alternative to meet the growing global demand for protein. But despite being one of the fastest-growing food industries in the world and playing a crucial role in global food security, its development also presents challenges (FAO, 2024). The water footprint in aquaculture is related not only to the direct use of water in farming systems, but also to feed production and effluent management.

Fish production in Recirculating Aquaculture Systems (RAS) offers significant environmental advantages compared to the production of land animals, including cattle, pigs, and poultry. RAS systems continuously reuse water, drastically reducing its consumption compared to other aquaculture methods and land-based animal protein production in general. While the water footprint of fish production in RAS is around 400 liters per kilogram of fish, beef can require more than 15,000 liters per kilogram, considering the direct and indirect use of water for pasture irrigation and feed production (Water Footprint Network). This disparity is mainly due to the longer life cycle of cattle and the high water requirements for maintaining pastures. In addition, other sustainability metrics, such as greenhouse gas emissions and land use, also favor sustainable aquaculture as a more efficient option, especially in regions where water is a scarce resource.

To mitigate the aforementioned impacts, it is essential to adopt innovative solutions, such as formulating feed with ingredients that have a lower water footprint and are circular (e.g., agro-industrial co-products or insects), the use of technologies for real-time monitoring of water quality and control of nutrient release, in addition to the integration of organisms from different trophic levels in production, as occurs in integrated multitrophic aquaculture (IMTA). This model, by combining fish, algae, and mollusks, optimizes the use of resources and reduces environmental impacts.

The integration of the water footprint with Life Cycle Assessment (LCA) represents a significant advance for sustainable water management. However, the implementation of these approaches still faces challenges, such as the difficulty in obtaining accurate data throughout the production chain, the lack of global standards for measuring and certifying the water footprint, and the need for greater awareness and incentives for producers and consumers to adopt sustainable practices. To overcome these barriers, it is essential that governments, industries, and communities work together to implement sustainable solutions, ensuring a more resilient future for global water resources.