Steam or UV — which type of bottle sterilizer actually works?

Across the reviewers we read, high-temperature steam is the consensus choice for reliable sterilization. Specialist communities like r/ScienceBasedParenting repeatedly flag that consumer UV boxes only work where light shines directly on a surface, need long exposure, and lose effectiveness as the lamps age. If sterilization assurance is the priority, steam units (and steam-based all-in-one washers) draw far stronger high-trust support than UV cabinets.