UV+Filtration, despite the myth it is not always enough to lock out bacteria
Even if UV and filtration can eliminate 99.99% (and even more) of bacteria from water and other liquids, the remaining 0.01% can sometimes cause many more problems than expected. Indeed, even those few bacteria can settle on surfaces in contact with water/liquid, forming the so called "biofilm". Since the number of such microorganisms grows exponentially (they duplicate themselves), this can be a huge threat, in particular in Food&Beverage production. By the way, more than 90% of bacteria live in biofilm (not free in the water), and this is also the ideal environment for the proliferation of pathogens. A real application case, from a large production plant, is available here.
More information