The LifeProducts™ Pure Water System® Granular Carbon Filters have been specifically optimized for use with Reverse Osmosis or Distillation Systems. The ultra pure water produced by reverse osmosis or distillation often requires post carbon filtration to remove VOC's (volatile organic chemicals), tastes and odors that may find their way past these systems. Granulated Activated Carbon Filters are available as "drop-in" cartridges that fit standard 10" filter housings. 0" filter housings.>