Cleaning your thermos correctly is crucial to prevent bacterial growth. Avoid common myths like only washing the cup body or using harsh tools, as these can lead to contamination. Instead, disassemble and clean all parts weekly with a soft sponge and neutral detergent. For deep cleaning, soak in a baking soda and vinegar solution monthly. Store high-protein drinks like milk for no more than 4 hours to avoid spoilage. Rinse immediately after use to prevent bacterial multiplication. When first using a new thermos, soak it in warm water with neutral detergent for an hour, rinse three times, and dry before filling. Be mindful of material-specific care—304 stainless steel should not store strong tea or carbonated drinks long-term, while 316 or pure titanium is more versatile. Avoid boiling water with plastic parts; preheat with warm water instead. Follow these tips to keep your thermos hygienic and durable!