The RockShox Reverb AXS (1st generation) is completely waterproof to the IPX7 international standard as long as the battery or battery cover is in place. Initially developed for construction vehicles and food sanitation, the IPX7 standard validates systems that require regular pressurized cleaning. For a mountain biker, this means no hesitation for stream crossings or getting caught in the rain.
For complete specifications, consult the Reverb AXS User Manual, found on the SRAM Service Site.