Its more about reducing demand so as to conserve water in the reservoir(s) in dry climates. Telling someone the amount of water on the planet is a constant won't endear you to anyone who's well/reservoir has just run dry.
I'm up in the interior, but do get back to Vancouver periodically. Meeting a bunch of new people for lunch, dinner, coffee (Mmm, coffee), whatever, sounds like fun. I'd love to try and make it to a future munch.
Speaking specifically to the poly, even if they don't ask, if you're sitting there petrified that they are going to find out/ask about it, the poly operator will know there is something on your mind (and that could read to them as reception, even if you are answering the question truthfully). So you might want to disclose if there are any remotely related questions. Good poly operators are very professional and non-judgmental. Odds are, you can't tell them anything they haven't heard before. Better to err on the side of telling all rather than failing the poly.