核心问题
quantities of water 的说法是否有误？water 为不可数名词，表示其数量的名词怎么能用复数呢？
词典解答
quantities of water (meat, sugar, blood, milk, information) 的用法是符合英语惯用法的。因为名词 quantity 除了作“与质量相对而言的数量”解，用作不可数名词之外，还可以表示事物的量，用作可数名词。例如：
-
He lost a great quantity of blood. (Palmer) 他流了大量的血。
-
A thirsty man will drink great quantities of water. (JED) 口渴的人会喝大量的水。
-
We've had quantities of rain this summer. (ALD) 今年夏天降雨量很大。
-
Modern industry needs considerable quantities of this metal... (STE) 现代工业需要大量的这种金属……
-
“What does Canada export?” “Large quantities of wheat ____ sent abroad.” A. is B. are C. have D. is being (Michigan)
-
The actual quantity of folic acid is required in the daily diet is not known. (TOEFL)
(应将 is required 改为 that is required 或 required)
(参见 amount/amounts)