The tiniest animal in The Lion King would most likely be Zazu who would be about 19 to 24 inches tall and weigh less than 1 pound.

Depends on what you mean by "animal." Technically speaking, there is a close-up of ants marching across a tree branch during the first song. If you count them as animals, they would be the smallest.

animals need water to drink. they can also go inside to swim or wash

Within the cells, it provides structure to the cells, and a transport mechanism for molecules and nutrients around the cells.

Between the cells and in the blood, it also provides a transport mechanism for nutrients, cellular waste, and various other needs of the body, including the movement of whole cells.

On mucous membranes, it provides a barrier to prevent the cells from drying out, and a significant amount is lost providing this function, especially in the lungs.

It is also a solvent for the excretion of nitrogen and water soluble salts in the kidneys (Urine).

Water is a vital part of digestion, and provides a medium for food to be broken down in the digestive tract, as well as being transported along the digestive tract. Much of it is reabsorbed in the large intestine, although some will remain in the stools.

I believe that water is consumed in some metabolic stages, but there is a net production of water by the bodies metabolism through the conversion of hydrocarbons into carbon dioxide and water.