My guess is that you will find some level of microorganisms inside of all packaged juices. You are likely to find some level inside of bottled water as well. The issue isn't that there are some present, the issue is when the number gets too high and / or some of the organisms are pathogenic.

Most packaged beverages are pasteurized before sealing in their containers. This means contaminating microorganisms usually are introduced after product manufacture through damage to the packaging.