Can the water content in concrete be considered "recycled content" for MRc4? I've seen this question show up in a variety of places and thought it was worth addressing LEEDuser's thinking on it, with help from our MR expert, former MR-TAG chair Nadav Malin. To paraphase Nadav:
I've seen this claim made before, but I'm very skeptical that it would be accepted (unless the reviewer isn't paying attention). Technically, yes, water is an ingredient in concrete, but I'd say that's really stretching things.
To claim that collected rainwater is "recycled" just because it didn't come from a municipal potable water source doesn't match any of the conventional definitions of a recycled material.
The case for reprocessed and reused water is a little better, but even there I think you'd be on thin ice because collecting, filtering, and reusing water is pretty standard practice at most plants.
You could try to sneak this through, I guess, but I certainly wouldn't count on it for a critical point you need for certification!