plain water

基本解释

But you can’t coat yourself with plain water because it just runs off.
但是很明显，你并不能简单的在身上涂一层水，因为这很容易挥发。
I also include a paintbrush and a lidded container with plain water in it for magic painting.
我还放了一个毛笔和一个装有水的带盖子的容器，它们是用来画魔术画的。
The Mars lander, by contrast, would visit a place where the seas — plain water in this case — vanished long ago.
与之相比，火星着陆器将会拜访一个淡水（如果有水存在的话）早已消失的地方。

Okay, how little plain water was actually consumed.
好,所喝的白开水很少
耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

To truly stay well hydrated, you likely have to drink more coconut water, than if you drink plain water.
FORBES: The Truth Behind The Coconut Water Craze
The bottom line is that most people who lightly exercise do not need sports drinks or even coconut water- plain water is just fine.
FORBES: The Truth Behind The Coconut Water Craze
While coconut water is low in calories, rich in potassium, and fat and cholesterol free, the evidence that it is actually better than plain water for simple hydration is unfortunately lacking.
FORBES: The Truth Behind The Coconut Water Craze