I've heard that, but I think it is more like you can add a little to stretch it. I'm just guessing, but maybe adding less than half to what you already have.
As far as the OP goes, here's my take. My pastor, said he never used the new rubrics. He found it too difficult to deal with is as he put it. I think he was just being euphemistc. Real Holy Water is an excorcism rite. The new rubrics are kind of weak.
Side note. I had a batch that must have been really salty awhile back and it left a white abrasive stain on the bottom of the glass bowl we keep it in. For some reason, I took a brush to it and most of it was coming off, though I had tried before to no effect. Getting bold I tried to really scrub it. The bowl dropped on my kitchen floor which is in an old house. The floor is what they call mud tile. Everything breaks if dropped. It is very hard.
Anyone want to guess what happened to the bowl that has been holding this real Holy Water? It bounced about five times and not a scratch on it