Its hard to say really. It was submerged in flowing water (2ft) a few times during the day, but only for like one minute per submersion . It was also raining outside, so the total moisture level was very high (my clothes were wet also). The condensation under the camera lens appeared 6-8 hours after the submersion. I was spending my time mostly semi-outdoors in a cover for the rain. There was also some steam caused by the heaters and wet clothing.
I have tested it's waterproofness in a sink before, and there were no problems whatsoever. So either the water flow, the high-humid environment, or the steam was too much. However my friends also had their phones with them, and they didn't get any water inside their phones. The only difference was that I submerged my phone while my friends didn't.