I thought about the implications of not wet water for a while, too, including things like:
- What happens if you drink it? Does the magic disappear and make it wet again?
- What happens if you spit into it or cry or pee or whatever?
- Which part of the water is dry? Only the water molecules? Would dirt or salt still stick to you? It's like those questions from that song Particle Man: If he's under water does he get wet? Or does the water get him instead
But ultimately I decided that there's no need to bother about it, because this world has magic and we've seen quite a lot of weirder things already, what with Dark Cell and the Pit, but also Bern's new swords or floating rocks or literally anything about Mary.
Dry water is simply in that uncanny valley that make us feel more uncomfortable than magical barriers or various elemental spells like what Suspiria used in her first fight against Mary.