All Clear does not purify surfaces on the outside of the drinking container including the threads of a water bottle. Users should check the threads and use a clean piece of cloth to wipe off the threads of the bottle before drinking. Another way to address this issue is to use the All Clear Pre-Filter, particularly in fresh water sources like lakes or streams where water contact with the threads is more likely. The All Clear Pre-Filter conveniently snaps over the opening of the .75L bottle and is designed to keep the threads dry while submerging the bottle into your water supply. Always check the threads for water droplets before drinking.