The iPhone 8 and 8 Plus are water resistant.
The rating for the Plus is “IP68” which means the new iPhone 8 are fully protected from dust and can handle being under freshwater for up to 30 minutes at a depth of 1.5 metres. If your phone gets dropped in a puddle, a shallow pool, or wet from the rain, it will be just fine. Steam from your bathroom shower, however, is not included in this rating, so rather keep it away from steam