Water Dependency Index (WDI)

The Water Dependency Index (WDI) measures what share of a territory's, sector's or organisation's total water footprint is satisfied with imported virtual water, that is, the water embedded in goods and services produced in other basins or countries. A high WDI indicates significant exposure to climatic, regulatory or geopolitical events occurring outside one's own borders.

How it is expressed

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

The higher the percentage, the greater the reliance on water resources located elsewhere. There is no single official scale for the WDI, so any thresholds used to label dependency as low, moderate or high should be defined transparently within each study rather than treated as a standard.

Components of imported water

• Crops and food products: soy, wheat, rice, coffee.
• Textile fibres: cotton, viscose.
• Minerals and metals: lithium, cobalt and bauxite used in batteries and electronics.
• Manufactured goods: clothing, electronics and vehicles.

How it is calculated

1. Build an inventory of imported goods, using customs and trade data (for example UN COMTRADE).
2. Assign virtual-water coefficients per product, drawing on sources such as FAO and the Water Footprint Network.
3. Estimate the imported blue, green and grey water.
4. Add the domestic water footprint from internal production.
5. Apply the WDI formula.

Why it matters

• Food and supply security: a high WDI signals vulnerability to droughts or export restrictions in supplier countries.
• Displaced impacts: ecological pressure occurs far from the consumer, which can carry reputational risk. This links to the displaced environmental footprint.
• Trade policy: it informs debates on water-related border measures for water-intensive products.

How to reduce the WDI

• Diversify sourcing and avoid over-concentration in highly water-stressed basins.
• Strengthen efficient domestic production through precision irrigation and drought-tolerant crops.
• Substitute particularly water-intensive inputs where feasible.
• Use resilient procurement contracts with suppliers committed to water stewardship.
• Invest in water efficiency in partner countries to stabilise supply.

Integration into corporate ESG reporting

• Report water dependency within water-risk disclosures such as CDP Water.
• Link WDI-reduction goals to corporate water neutrality strategies.
• Publish progress and mitigation actions in sustainability reporting under the CSRD.

Limitations

• Data quality: virtual-water coefficients vary with local farming practices and need periodic updating.
• Time lag: annual customs data can hide short-term shocks.
• Partial coverage: virtual water in services or tourism is hard to quantify.

Related indicators

• The Footprint Displacement Index (FDI) broadens the idea to other environmental footprints.
• Water security: a high WDI tends to reduce national water security.
• Water vulnerability: external dependency increases exposure to events beyond domestic control.

The Water Dependency Index reveals how consumption is connected to distant water resources, and why diversification, efficiency and cooperation matter for resilience in a changing climate. At Manglai we help companies measure their water and carbon footprints and assess their environmental risks. Discover how Manglai can help you.