Here's why:
* Eucalyptus leaves aren't very hydrating: Though eucalyptus leaves contain some moisture, it's not enough to meet the koala's needs.
* Koala physiology: Koalas have a specialized digestive system that extracts water from eucalyptus leaves, but they still need to drink water regularly, especially during hot weather or droughts.
* Observation: Koalas have been observed drinking from puddles, streams, and even water dishes provided by humans.
So, while koalas are experts at getting water from their diet, they still need to drink water occasionally to stay healthy and hydrated.