- Water: Blue, Green, Grey
- "Blue water"
- 38.8% of total precipitation.
- Equivalent to the natural water resources: collected in rivers, lakes, wetlands and groundwater.
- Available for withdrawal (1.5% for direct human use) before it evaporates (1.3%) or reaches the ocean (36%).
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- "Green water"
- 61.1% of total precipitation.
- The rain water absorbed by soil and plants.
- Never available for capture or storage because it evaporates or transpires from non-irrigated agriculture, pastures and forests.
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- "Grey water"
- Urban and industrial waste water.
- The systematic reuse of waste water for nonpotable applications, with or without treatment, increases the overall efficiency of use of water extracted from primary sources.
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- 3% of all water on earth is fresh water, the rest is salty.
Source: FAO - Food and Agriculture Organization, IWMI - International Water Management Institute )
