adding that much water will make your crete really weak and brittle. in that applocation, it really doesn't matter to much, since it's just filling in the gap, but for future reference, you make concrete smooth by working it, not adding water. besides, you have what's called a "cold joint" there, so the new concrete won't stick to the old.
there's a ton of epoxies that would fill that kinda shit in and look pro as hell. after all the crapcrete you have in that crack chips out, just use bondo or something similar.
remember.... when you're spotfixing, you usually wanna make it look as good as possible to insure that people don't notice your "repairs," and if they do, they won't get bummed on how crappy it looks.
i might sound like a dick, but i'm honestly trying to help.