The blue water footprint refers to water withdrawn from surface or groundwater sources (e.g., aquifers, rivers, lakes) and consumed during production, which is not returned to the source in a usable form.

The green imprint concerns rainwater that is used for production, especially in agriculture or forests. It does not include direct withdrawals, but rather water that is stored in the soil and absorbed by plants.

The grey water footprint represents the volume of water required to dilute pollutants and return the used water to the quality levels required by environmental standards.