Water Footprints of Industrial Products

The three water footprints:Green water footprint is water from precipitation that is stored in the root zone of the soil and evaporated, transpired or incorporated by plants. It is particularly relevant for agricultural, horticultural and forestry products.Blue water footprint is water that has been sourced from surface or groundwater resources and is either evaporated, incorporated into a product or taken from one body of water and returned to another, or returned at a different time. Irrigated agriculture, industry and domestic water use can each have a blue water footprint.Grey water footprint is the amount of fresh water required to assimilate pollutants to meet specific water quality standards. The grey water footprint considers point-source pollution discharged to a freshwater resource directly through a pipe or indirectly through runoff or leaching from the soil, impervious surfaces, or other diffuse sources.Components of agricultural water footprint: green, blue and grey (from SAB Miller and WWF, 2009)The relation between consumption and water use“The interest in the water footprint is rooted in the recognition that human impacts on freshwater systems can ultimately be linked to human consumption, and that issues like water shortages and pollution can be better understood and addressed by considering production and supply chains as a whole,” says Professor Arjen Y. Hoekstra, creator of the water footprint concept.http://waterfootprint.org/en/water-footprint/what-...

三类水足迹具体如下：
1. 绿色水足迹（Green water footprint）：指源自大气降水、储存于土壤根区，并经蒸发、植物蒸腾或被植物吸收利用的水资源，该指标与农业、园艺及林业产品的关联尤为紧密。
2. 蓝色水足迹（Blue water footprint）：指取自地表水或地下水资源，经蒸发、融入产品，或从某一水体取用后排入另一水体，或在不同时段回流的水资源。灌溉农业、工业及生活用水均可产生蓝色水足迹。
3. 灰色水足迹（Grey water footprint）：指为将污染物同化至符合特定水质标准所需的淡水总量。其涵盖通过管道直接向淡水水体排放的点源污染，或经由径流、土壤渗滤、不透水表面及其他面源间接产生的污染。

农业水足迹的组成：绿色、蓝色与灰色三类（来源：SAB米勒公司与世界自然基金会，2009年）

消费与用水的关联
“水足迹概念的诞生，源于人类意识到人类对淡水系统的影响最终可追溯至人类消费行为；且通过整体考量生产与供应链，能更深入地理解并解决水资源短缺与水污染等问题。”水足迹概念的创立者阿尔让·Y·赫克斯特拉（Arjen Y. Hoekstra）教授如是说。
相关链接：http://waterfootprint.org/en/water-footprint/what-...