Water is a very important factor in gerbil care. Even though gerbils are desert animals,
they still need to have constant supply of water. In the wild, gerbils would lick the dew from the pebbles, but we cant just spray some pebbles with water in the tank! Everything would get soggy and wet. However, we can use a water bottle instead. Its the best way to give water.
Water dishes are NOT recommended, as gerbils will kick bedding in them, spill them, use them as bathrooms etc. It is much more sensible to buy a water bottle.