This is the 285th most frequent Chinese word.
水
Water.
In this sentence, '水' refers to water as a natural element.
水是生命之源。
Water is the source of life.
Here, '水' refers to the drinking water needed to stay hydrated.
我今天喝了很多水。
I drank a lot of water today.
In this case, '水' is used to denote potable or commercial bottled water.