Gerbils in the wild have a few ways to lower the levels of water they require, but they don’t do these things because they’re happy to, they do it because they need to in order to survive. It’s also important to understand that gerbils kept in captivity don’t have the same abilities as those in the wild - they’ve been bred in comfortable houses for many years and so won’t do well if they are subjected to these pressures. Gerbils kept in captivity should have water constantly available to them.
Like all mammals, gerbils need water to survive
Gerbils have specialised kidneys that enable them to urinate less than other species, as well as interesting fat cells that are capable of storing water. However, they still need water, which they can sometimes obtain from a number of water-rich foods.