If a person has too much or too little water, what will happen to them?

Excess water can lead to lower sodium levels in the body, which may further lead to nausea, vomiting, cramps, fatigue, et al. This condition is known as hyponatremia. 2. Headaches are signs of both over-hydration and dehydration

Excess water can be called over hydration.

Overhydration can lead to falling electrolyte levels, which can cause headaches, nausea, and muscle weakness. If your lips, hands, and feet are swollen, you may be drinking too much water.

And less water in the body is dehydration

When your body is dehydrated, the kidneys retain as much fluid as possible to maintain their function. This can lead to decreased urination—one of the most common signs of low water intake. Lack of water can cause your urine to become darker in color, stronger in odor, and cloudier in appearance.

they deliver oxygen to the blood