While Apple is silent on the exact waterproofing standards of the refreshed iPhones, one YouTuber has decided to find out for himself.
http://www.notebookcheck.net/YouTuber-performs-first-hand-waterproof-tests-for-iPhone-6s-and-6s-Plus.151081.0.html
Maybe Apple doesn't mention water proof because at the same time they sell water damage insurance that doubles profit margin? Not that Apple is all about money.