Would the originating country matter in the discussion?
We missed the tiger cubs, saw two of the elephants and glimpses of the third behind a door while the enclosure was cleaned and adored the new orangutan home. Photos and perhaps some commentary later.
Melbourne Zoo has recently been "outed" as one of Victoria's top 200 water users. Many on this list are on it simply due to their size (hospitals, huge breweries, government departments, the casino). A better list might have been water usage per customer or per employee (or perhaps per-manufactured-serving) instead of a most-litres-used list.
Since our last visit six months ago the level of water usage has dropped significantly in very obvious ways. The main lake in the middle of the park (where the pelicans live, near the elephants and oranguan) has a much lower water level. The bear enclosure's pond is almost empty. Any permanent water features in the big cat enclosures are empty. Most of the grassed areas are browning. Fountains were not running.
The effects of enforced reduced water usage were everywhere.
And yet... periodically we witnessed the orangutans and tree kangaroos sprayed with a mist of water for cooling, 99% of which landed no-where near the animals. The elephants had a large pool to swim in. Not to mention those silly wasteful seals.
Keeping animals will always use a lot of water. Let's not get into the obvious water requirements of the aquarium.
I suppose eventually, if it got bad, it would come down to a choice. What is more important? Using almost 4 litres of drinking water per litre of beer manufactured, or using X litres to keep keep each elephant alive per year, for X number of people to look at it for 5 minutes?