Fluids and water can take many forms in the human body. Good forms of “fluid” in the body are many-fold and include the substance that lubricates your eyes, the material that surrounds the baby in the uterus before birth and many more.
Bad forms of water/fluids in the body would be the many things that people experience that cause discomfort, including a sensation of foggy–headedness, nasal congestion, runny nose, a productive cough, edema, excessive urination, excessive fatty tissue in the body (one way to think of fatty is a condensed version of phlegm, interestingly), and even cysts and or tumors.
So no, water is not simply just the stuff that you drink out of a glass and is not in the body easily replaced by simply “drinking more water.”
There are key systems in the body such as the spleen/pancreas, the stomach, the lungs and the kidney/adrenal that are in charge of the distribution, metabolism and elimination of water throughout the body. If you get those systems working, and you eat a diet that doesn’t increase dangerous fluid production in the body, you will have a balance of fluids and not experienced negative effects of “bad” fluids.