No, not totally waterproof... they're about as waterproof as the Teton soft bags and Rainier tank bag. If you want totally waterproof you'll need a waterproof stuff sack , which is what I use inside them. Wolfman do an expedition range which is waterproof: they're like mini duffle bags. I've also used 2x 10L Kriega bags on the ADV-spec crash bars without any modification: they're waterproof.