First of all not all water is equal.
So really it isn’t about total water but what kind of water.
The water that pastured animals get is almost entirely green water. It falls as rain. It’s not blue water that is pumped to them. All animals can be pastured.
Studies comparing cows milk to milk alternatives don’t even take into account the vast difference between how milk alternatives use mainly blue water and cows use mainly green water.
* One main difference among all methods for assessing water use is whether and how they include green and gray water. The “water footprint” approach includes green water, whereas life cycle assessment approaches tend to exclude green water or to include only the variation in green water resulting from changes in land use. A second difference is whether water use is reported as a volume of water or as an index of water-use impact (e.g., H2O equivalents). A third is whether water that returns to the same location (e.g., in urine) is considered to have been consumed.
* Because of these differences and the fact that existing studies have analyzed only a limited number of different livestock production systems, methods give wildly different results for the same livestock product. For example, estimations of water use to produce 1 kg of beef range from 3 to 540 L of H2O or H2O equivalents for the life cycle assessment approach and from 10,000 to 200,000 L of H2O for the water footprint.
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