Water Use Intensity
Water consumed per unit of product or service.
Formula
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Example
Liters of water per kg of food
How it works
Water Use Intensity (WUI) measures how much water is required to produce one unit of output, so it is a simple efficiency indicator. It works by dividing the total water volume used or consumed by the number of units produced, which lets you compare different products, facilities, or time periods even when their overall sizes are very different. A lower WUI means less water is needed per unit of output, which usually indicates better water efficiency.
When to use it
Use this formula when you want to compare the water efficiency of factories, farms, power plants, or service operations. It is especially useful for tracking resource use over time, benchmarking against competitors, or identifying processes that waste water.
Worked example, step by step
A beverage plant uses 12,000 liters of water to produce 4,000 bottles of juice. WUI = V_water / Output WUI = 12,000 L / 4,000 bottles WUI = 3 L per bottle So, the water use intensity is 3 liters of water per bottle produced.
Common mistakes to avoid
- Using the wrong output unit, such as mixing cases, bottles, and liters in the same calculation
- Forgetting whether water is withdrawn, consumed, or discharged, which can change the meaning of the result
- Comparing WUI values from different products or facilities without matching the same time period and output basis
Did You Know?
Beef has one of the highest water footprints of any food.
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