Is Juvia a Water Dragon Slayer? Is it possible for Juvia to be a Water Dragon Slayer to be in Fairy Tail? 

It's honestly making me feel like it and it's now a theory I'm asking myself now if Juvia could be a Water Dragon Slayer?
No, she's not a water dragon slayer. Here is why:


She never "eats" her element to power up, she only drinks water like normal people.
Not from any generation of Dragon Slayers:


Not a first generation Dragon Slayer. She has never learn her Magic from an actual Dragon.
Not a second generation Dragon Slayer. She has never had Dragon Lacrima implanted into her body.
Not a third generation Dragon Slayer. She has never both learn her Magic from an actual Dragon and had Dragon Lacrima implanted into her body.
Not a fourth generation Dragon Slayer. Not an artificial beings created from Dragon Lacrima. (From the movie)

None of her skill something like "Roaring Magic".
None of her magic use the word "Dragon" unlike all Dragon Slayers.
Never has seen to have motion sickness like Natsu.
Never has seen to have dragon scales.
When fighting Dragons, her magic didn't have any effect on them. (the only magic that can hurt dragon is Dragon Slayer magic).
Like I said in the comment, the premises is to have 7 dragon slayers in FT side and they are Natsu, Gajeel, Wendy, Laxus, Cobra, Sting and Rogue. There's no chance of an 8th Dragon Slayer.