The first evidence of good sealing, according to the video, is the copious amount of adhesive applied to the inside of the back panel, which should keep the lid stuck tight to the phone. It apparently has "more adhesive than an LG phone, but less than a Samsung."
Nelson has ended his video by stating that "the water resistance of the OnePlus 6Where to buy
34999 39999 is on par with other flagships that actually do have an IP rating." Considering that, no one's really sure why the Chinese brand's newest flagship never got its own IP rating, but it's probably right to assume that OnePlus simply decided to err on the side of caution than face potential lawsuits over a glass of spilt mojito.