Sorry to rain water on your parade, but I've seen this book's release dates as last April, September, Christmas, and now April 2013. Not to mention John and Colin post frequently on their Facebook pages that they are working on the water book (the most recent one was last week I think).
These guys seem like they are really trying to nail to info down rather than crank out a book, which I absolutely appreciate.
I hope it's out for NHC so I can get my copy signed...but if not, I can wait.
Besides, I still have the other books I haven't finished. I get sleepy when I read so it takes me longer