Use sink water to flush toilet - brilliant idea - I have always thought it ridiculous that we use potable water to flush our toilets! I've always wanted a containment system for hand washing water and shower water for toilets.
Pinned for the idea. Not sure how much I like the extension over the toilet. If were to do, vanity top should be one piece, with no cut line. Also: Consider how much the extra counter space would be needed.