@JeremyECrawford So, I've heard the question brought up quite often. I personally rule it as no, since it is too powerful of an effect for such a low level spell. HOWEVER, in an attempt to settle the debate, does Create or Destroy water damage Water Elementals?
— Anthony McGraw (@AnthonyMcGraw89) January 26, 2018
The create or destroy water spell can destroy up to 10 gallons of water in an open container. A water elemental is not water; it's a creature. #DnD https://t.co/BJ4FeqrvTe
— Jeremy Crawford (@JeremyECrawford) January 26, 2018
I assume this logic safe to apply to other "classes" as well. The base class of a Water Elemental is an Elemental, but it's "affix" -or "subclass"- is Water.
Thus a Fire Elemental would not be affected by Destroy Fire, nor would an Earth Elemental by um, a Bulldozer… spell…?
— Forrest G Emerson (@StabbyGM) January 26, 2018
Monsters are creatures. Spells and other effects that target objects or environmental phenomena are ineffective against them. #DnD https://t.co/JlJgVIxBoI
— Jeremy Crawford (@JeremyECrawford) January 26, 2018
Yeah no. With respect, this is far too ludicrous literalism for my tastes. A WATER elemental is by definition WATER, from the Elemental Plane of WATER, not water-appearing non-water substance. Either living water or spirit-animated water. Sometimes a cigar is just a cigar! I gave you our story intent. An elemental of whatever kind is an extraordinary creature associated with an element, but it is not that element. You're definitely free to alter that story in a campaign you run.
— Jeremy Crawford (@JeremyECrawford) January 26, 2018