打開水龍頭—手心向上—拱起—捧水，就形成一個簡單又快速的漱口杯，這個行為看似無傷大雅，實則浪費甚多，如果你願意花150元買一個簡便的漱口杯，那你每刷牙一次就能比你嘩啦嘩啦開著水龍頭漱口還要省5L的水，假設你一天刷牙2次，一天就少了10L的用水，一個月更能省下300L的自來水，300L的水又相當於600瓶的礦泉水，600瓶呀！
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？
早上睡眼惺忪習慣來一杯咖啡、生日大餐習慣吃上等牛排、剛下班精神耗弱習慣來一瓶啤酒、心情不好習慣去大血拼等等......，其實在這些日常習慣的背後都隱藏著龐大的用水鏈。
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）。
利用水足跡的想法，來探討個人水足跡，個人水足跡＝實際用水＋虛擬水。像是洗衣打掃、刷牙洗臉、沖馬桶，這些看得到的耗水即是實際用水，但實際用水其實僅佔個人水足跡的4%，接下來要談的虛擬水，可能超乎你的想像，尤其是我們每日需要的食物，它們背後的用水量很可觀。
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.
