Water footprint is more than what you think
2 min Read

我們日常所耗費的水資源真的需要被好好珍惜,但除了了解日常的用水小撇步外,你有聽說過「水足跡 (water footprint)」嗎?


1993年倫敦國王學院的約翰・安東尼・艾倫教授(John Anthony Allan)提出虛擬水的概念,意思即是生產一個商品或服務背後所需要/參與的水資源,其後也延伸出水足跡,而水足跡又分為三類:藍水足跡(泛指可地表、地下可被利用的淡水資源)、綠水足跡(儲存在土壤中讓植物使用的水資源)以及灰水足跡(生產過程中遭受污染的必要用水)。

Gargling with water held by hands is actually wasting more water than gargling with a water cup. If you are willing to spend NT.150 to buy a simple water cup, you can save 5L of water compared to gargling on the tap. If you brush your teeth twice a day with a cup, it means you can save 10L of water a day, and 300L a month, which is equivalent to 600 bottles of mineral water. 600 bottles!

The water we consume every day really needs to be cherished. But apart from the water saving tips, have you ever heard of the "water footprint"?

There is a huge water chain hidden behind our daily habits, such as getting a cup of coffee in the morning, having luxury steak to celebrate birthday, drinking beer afterwork, and lifting oneself by going shopping, etc.

In 1993, John Anthony Allan, an emeritus professor at King’s College London, invented the concept of virtual water, which referred to all the freshwater that was consumed or transformed in order to produce commodities or services at their point of origin, and which was then traded across international lines embedded in these commodities or services. This concept was extended to the concept of ‘Water Footprint’, including three categories: blue water footprint (referring to freshwater resources that can be used on the surface and underground), green water footprint (water resources stored in the soil for plants to use), and gray water footprint (polluted water during production).

The water footprint shows the amount of water used to produce each of the goods and services we use. Personal Water Footprint = Actual Water Use + Virtual Water Use. For example, washing and cleaning, brushing your teeth, and flushing the toilet are the actual water use. However, the actual water use only accounts for 4% of your personal water footprint. The virtual water is far beyond our imagination. Especially for the food we need every day, the amount of water use is considerable.

These are just the tip of the iceberg of virtual water. In order to reduce the water footprint with the aim for sustainability, what we can do is making small changes in daily life, such as shopping rationally, having less meat and milk, and reducing food waste.