Imported Virtual Water

Imported virtual water is the volume of freshwater (green, blue and grey) that a country, region or company indirectly incorporates when it imports goods and services produced in other territories. It measures external dependence on water resources and is used to assess exposure to risks such as drought, conflict or regulatory change in supplying river basins. The concept derives from the broader idea of virtual water, first formalised by Tony Allan in the 1990s.

How it is calculated and its link to trade

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

Water footprint factors: these are drawn from databases such as the Water Footprint Network's WaterStat, FAO AQUASTAT or, ideally, primary supplier inventories.

Colour classification:

• Green: rainwater incorporated into production.
• Blue: surface and groundwater used for irrigation or processing.
• Grey: freshwater required to dilute pollutants generated during production to meet quality standards.

Why it matters geopolitically and economically

Food security: water-scarce countries often import virtual water in the form of cereals to relieve internal water pressure, a pattern studied in arid regions such as the Middle East and North Africa.

National water strategy: it complements the water balance by revealing hidden deficits that are effectively covered through trade.

Supply risk: droughts in exporting basins can translate into price inflation and shortages in importing countries.

Global scale

According to Mekonnen and Hoekstra (2011), international virtual water trade flows averaged around 2,320 km³ per year over 1996-2005, of which roughly 88% related to trade in agricultural products. The largest exporters of virtual water include the United States, Canada, Australia, Argentina and Brazil, while many industrialised and water-scarce economies are net importers. These figures are estimates and vary between studies and years, so they should be treated as orders of magnitude rather than precise accounts.

Link to the Water Dependency Index (WDI)

Imported virtual water feeds directly into the Water Dependency Index (WDI):

WDI (%) = imported virtual water / total water footprint × 100.

A high WDI (above 50%) signals strong external vulnerability and a large displaced environmental footprint, because the environmental pressure of consumption falls on other territories.

Strategies to reduce or manage imported virtual water

• Diversify suppliers towards basins with low water stress (for example, regions with a low AWARE characterisation factor).
• Substitute high water-consuming ingredients where feasible (for example, replacing almond with oat in some food and beverage applications).
• Co-invest in efficiency at origin: precision irrigation, wastewater treatment and improved agronomy.
• Agree long-term contracts with water clauses and support recognised water stewardship certification, such as the Alliance for Water Stewardship (AWS) Standard.
• Provide clear product information so that buyers can factor water intensity into purchasing decisions.

Emerging trends and policies

• Water border adjustment mechanisms: academic proposals, conceptually similar to the EU Carbon Border Adjustment Mechanism (CBAM), for products with high blue water content.
• Digital Product Passport: the Ecodesign for Sustainable Products Regulation (ESPR) introduces a Digital Product Passport that can carry environmental information, including water-related data, for priority product groups.
• Green finance: green finance instruments such as blue bonds can fund water-saving projects in exporting countries.

Measuring imported virtual water reveals invisible water dependencies and helps governments and companies anticipate risks, optimise supply chains and contribute to global water sustainability. At Manglai we help organisations measure their water and carbon footprint and prepare robust sustainability reporting. Discover how Manglai can help you.