you don't have as much water in your system 其中的as much 做什么成分呢

you don't have as much water in your system 其中的as much 做什么成分呢

相当于enough,
as 一般修饰原级,表示比较的意思,much表示量的多少,修饰不可数名词（my height is not as tall as you 我没你高）,所以此处可理解为一个省略,更容易消化：还原：you don't have as much water as （that）is needed in your system.与你系统中所需的水分量相比的话,你没有足够的水分.that可省略,带指 水量.
引申翻译为：你的水分不足以满足系统中的水分需求量.
as much是定语,用来修饰water.

as much=那么多

as much 一般情况下是有“也，同样多的”意思，但是你可以灵活变动一下，在这里应该是“那么多”的意思 这句话里 做的是形容词 修饰water