This site describes the waterhole as follows:
Werribee Open Range Zoo Expansion / ARM Architecture
a waterhole precinct, with places to view animals, places to rest, and amenities for visitors.
It later mentions a Waterhole Cafe.
It appears they’re playing on ‘waterhole’ theme to create an eating/drinking/guest amenity hub with a handful of accompanying animal exhibits. Whether that will correspond to the exhibit being waterhole drinkers (primarily ungulates) is unclear.
Bachelor exhibits for species like Waterbuck and Lowland nyala could be a possibility given the requirement to house these separately from the breeding herd - and considering the strong interest from people in seeing a bull nyala, which is strikingly different from the cows on display.