Bras, B., Tejada, F., Yen, J., Zullo, J. et al., "Quantifying the Life Cycle Water Consumption of a Passenger Vehicle," SAE Technical Paper 2012-01-0646, 2012, doi:10.4271/2012-01-0646.
Numerous studies have pointed out the growing need to assess the availability of water sources in numerous regions around the world as future forecasts suggest that water demands will increase significantly while freshwater resources are being depleted. In this paper, we highlight the difference between water use versus consumption and analyze the life-cycle water consumption of a car from material extraction through production, use, and final disposition/end of life and determine a car's water footprint using data from the EcoInvent database as well as data collected from literature sources. Although water use is typically metered at the factory level, water consumption (i.e., water lost through evaporation and/or incorporation into a material, part, and/or product) is much harder to quantify. As shown in this paper, the difference can be an order of magnitude or more. The use phase has significant impact on the overall vehicle water consumption, followed by material production, whereas end of life processing seems to be relatively insignificant. The assessment in this paper represents a life-cycle inventory assessment. The impact of water consumption varies by region and locality, and a differentiation of impact would still be needed whether the water consumption actually happens in water scarce regions or not.