You use the terrain thing where it triggers the terrains to go up and down. Go down and keep going until you see water!

u gotta press shift while ur doing it

go to animal items, click on water bowl

the first option:

go to terrain then click the change terrain button. pick a suitable place for water then
hold shift.

the second option:

click the animal enrichment menu. then go to exhibit enhancements then pick the water.
place it to wherever you desire.

enjoy playing the game!

the pool of water is indeed the best choice.
just go to terrain and dont press
the flatten terrain button. keep it so that
it makes hills. but while you click hold down shift and it
will not make a hill, itll make the water :p you can make it as big or small as you want.