Water Footprint
The Water Footprint rating assesses the impact of food production on water resources, considering both the volume of water used and the scarcity of water in the regions where it's consumed.
What It Measures
The water footprint indicator focuses on:
- Volume of water used in food production, processing, and transportation
- Water stress levels in regions where water is extracted
- Blue water consumption (surface and groundwater)
- Green water consumption (rainwater)
- Potential impacts on local ecosystems and communities
Water Types
Blue Water
Surface water and groundwater used for irrigation and processing:
- Rivers and lakes
- Aquifers
- Municipal water supplies
Blue water is typically scarce and its use directly competes with other needs.
Green Water
Rainwater stored in soil and used by plants:
- Precipitation captured by crops
- Soil moisture
- Generally less impactful than blue water
Grey Water
Water required to dilute pollutants:
- Agricultural runoff
- Processing effluents
- Not directly consumed but affects quality
Water Scarcity Weighting
The impact of water consumption depends heavily on location. A liter of water used in a water-stressed region has far greater impact than in a water-abundant area.
Water Stress Index (WSI)
Water consumption is weighted by the Water Stress Index:
| WSI Level | Description | Multiplier |
|---|---|---|
| Low | < 0.1 | 0.1× |
| Moderate | 0.1-0.4 | 0.4× |
| High | 0.4-0.8 | 0.8× |
| Extreme | > 0.8 | 1.0× |
Scarcity-Weighted Water Footprint
Impact = Water Volume × WSI × Characterization Factor
Rating System
The Water Footprint uses a 5-drop rating system where A is best (5 drops) and E is worst (1 drop):
| Rating | Drops | Meaning | Liters/DFU Threshold |
|---|---|---|---|
| A | 💧💧💧💧💧 | Better than average | < 91.6L |
| B | 💧💧💧💧 | Maximum twice the average | < 183.1L |
| C | 💧💧💧 | Maximum four times the average | < 366.2L |
| D | 💧💧 | Less than absolutely critical | < 1,059.9L |
| E | 💧 | More than absolutely critical | > 1,059.9L |
Rating A indicates optimal consumption of scarce water. Rating E means the water consumption is clearly in conflict with sustainable use.
High Water Impact Foods
Agriculture-Intensive
| Food | Water per kg | Notes |
|---|---|---|
| Almonds | 10,000+ L | California water stress |
| Rice | 3,000-5,000 L | Flooded paddies |
| Cotton | 10,000 L | Often in arid regions |
| Avocados | 1,000+ L | Chilean/Mexican stress |
Animal Products
| Food | Water per kg | Notes |
|---|---|---|
| Beef | 15,000+ L | Feed crop irrigation |
| Pork | 6,000 L | Feed and processing |
| Cheese | 5,000 L | Dairy production |
Low Water Impact Foods
| Food | Water per kg | Notes |
|---|---|---|
| Potatoes | 250 L | Rain-fed in many regions |
| Carrots | 130 L | Efficient water use |
| Cabbage | 200 L | Low irrigation needs |
| Onions | 270 L | Drought tolerant |
Regional Considerations
The same crop can have vastly different water impacts depending on where it's grown:
Example: Tomatoes
| Origin | WSI | Impact |
|---|---|---|
| Netherlands (greenhouse) | Low | Minimal |
| Spain (Almería) | High | Significant |
| Morocco | Extreme | Very High |
Benchmark Methodology
Water benchmarks are calculated using:
- Production data from EDB and Ecoinvent
- WSI values from global water stress maps
- Trade statistics to weight by origin
- Characterization factors from AWARE method
AWARE Method
The Available WAter REmaining (AWARE) method is used for impact characterization:
- Accounts for water availability
- Considers human and ecosystem needs
- Globally consistent methodology
- ISO 14046 compliant
Data Sources
- Pfister et al. (2011) — Global crop water impacts
- Scherer & Pfister (2016) — Freshwater biodiversity
- AWARE characterization factors
- National water statistics
See Also
- Water Benchmark — Benchmark details
- Ratings Overview — All rating categories
- Methodology — Calculation methods