When the priest casts a create water spell, four gallons or more of water is created in a place designated by the caster. The water is clean and drinkable (it is just like rain water). The created water can be dispelled within a minute of its creation; otherwise, its magic fades, leaving normal water that can be used, spilled, evaporated, etc.
The reverse of the spell, destroy water, obliterates without trace (no vapor, mist, fog, or steam) a like quantity of water. Water can be created or destroyed in an area as small as will actually contain the liquid, or in an area as large as 27 cubic feet (1 cubic yard).
Note: This spell originally appeared in this form in the 2nd Edition Player's Handbook for Advanced Dungeons & Dragons from TSR. Its use here is for the purposes of providing context for the campaign only.