When the Pixel phones were officially announced by Google, or actually even before they were officially announced, it was revealed that they would not feature the same level of water-resistance that we have seen from various Samsung phones or the iPhone. Instead the handset was revealed to only have an IP53 rating.
So what gives? Turns out that Google had originally intended to give its Pixel phones waterproof capabilities, but ultimately ran out of time to do so. This was revealed in a WIRED podcast around the 32 minute mark (via Pocket Now) where Google had told them that they planned waterproof features, but towards the end of 2015 they decided to start over with its Pixel phones, meaning that they only had about 9 months to design and produce a handset from scratch.
It is because of this that the waterproof features got omitted, presumably because Google wanted to focus more on the core features and waterproofing was tossed to the wayside. That being said, the Pixel phones have so far been pretty well-received. Despite its IP53 rating, a recent water test has revealed that the phone is actually able to survive being submerged underwater for about 30 minutes.
Granted this could be an anomaly so don’t go around dunking your Pixel phones just yet, but from the test it does seem to suggest that the phone could be tougher than we thought.