Imported Virtual Water

Imported virtual water measures external dependence on water resources and is used to assess exposure to risks such as drought, conflict, or regulatory changes in supplying river basins.

Calculation and relationship with trade

Basic formula: Imported virtual water (m³/year) = Σ (volume of product imported × water footprint factor of the country of origin)

Water footprint factors: Sourced from databases such as WaterStat, FAO AQUASTAT, or primary supplier inventories.

Colour classification:

• Green: rainwater incorporated into production.
• Blue: externally sourced irrigation water.
• Grey: water required to dilute pollutants generated during production.

Geopolitical and economic importance

Food security: Arid countries import virtual water in the form of cereals to relieve internal water pressure (e.g. Egypt, Saudi Arabia).

National water strategy: Complements the water balance by revealing hidden deficits covered through trade.

Supply risk: Droughts in exporting basins can translate into price inflation and domestic shortages.

Global data (2024)

• Global agricultural trade mobilises 2,160 km³ of virtual water annually.
• Japan imports 125 Gm³/year (Water Dependency Index: 78%).
• The EU imports 620 Gm³/year, mainly soybeans and cocoa.

Link to the Water Dependency Index (WDI)

WDI (%) = Imported virtual water / Total water footprint × 100

A high WDI (>50%) indicates strong external vulnerability and a displaced environmental footprint.

Strategies to reduce or manage Imported Virtual Water

• Diversify suppliers towards basins with low water stress (AWARE < 5).
• Substitute high water-consuming ingredients (e.g. almond → oat).
• Co-invest in efficiency at origin: precision irrigation, wastewater treatment.
• Long-term contracts with water clauses and AWS certification.
• Virtual water labelling to inform consumers and encourage responsible purchasing.

Emerging trends and policies

• Water border adjustment mechanisms (academic proposals), similar to CBAM, for products with high blue water content.
• The Digital Product Passport (ESPR) will include virtual water information for textiles, batteries, and processed foods.
• Green finance opportunities: blue bonds focused on water-saving projects in exporting countries.

Case study: Coffee supply chains

Spanish company: 70% of its imported virtual water comes from Brazil and Vietnam.

Strategy: Contract with a Colombian cooperative using agroforestry practices and Rainforest Alliance certification.

Result: An 18% reduction in imported blue water and an improvement in CDP Water score from B to A-.

Measuring imported virtual water reveals invisible water dependencies and enables governments and corporations to anticipate risks, optimise supply chains, and promote global water sustainability.