Really... all I know about water in real life? Water associated with a molecule composed by two hydrogen atoms and an oxygen, though the substance is generally a mixture of that with minerals and other impurities, that are dissolved into the liquid. It has a boiling point of 100ºC and a freezing point of 0º, so it's in liquid state at room temperature. When frozen is called ice and is actually less dense than liquid water, due to a whole lot of physics jibberish that I'm not willing to gorge out right now. It's a poor thermal conductor as it takes quite a lot of energy for water to increase it's temperature, and, depending on the amount of impurities dissolved in them, it's a good conductor of electricity. It's one of the most abundant substances in the world is the basis of life on earth, being essential in most metabolic systems of living beings, structural support and just general life support.
The Narutoverse follows the RL closely, at least in terms of the laws of nature, chakra serves only to augment that reality, not alter it. Water in the narutoverse follows the same properties as water in RL. Suiton, though, or water created through chakra, is commonly perceived as a translucent river-like liquid, though variants exist for a syrup-like or oil-like substance. Water/Suiton is one of the 5 basic chakra natures that serves as the building blocks for all advanced natures. When you ask me about KG that utilize Water, I'm assuming you mean elemental Kg. Wood is composed of Earth and Water, Ice is composed of Wind and Water and Storm is composed of Lightning and Water. The 5 basic elements have a relationship of strength and weakness with two other basic elements. Water is strong to Fire, because water douses fire and absorbs heat onto itself, and is weak to Earth, because it's less tangible and can be blocked, redirected and absorbed by Earth. It conduces lightning and can have it's temperature lowered by wind or be sharpened, but, in terms of power, it is neutral/equal to either of them.
I think that's the gist of it