Suitable for removing hard water contaminants, e.g Calcium Carbonate. Four liters capacity. Comes with six activated charcoal sachets. Missing small seal on top of plastic water collecting bottle. We used previous same type of model for 8 years to prep water for our coffee machine. It still worked fine but I dropped it. This one used for 2 years and then we switched to filtered water on advice of coffee machine service people. I expect this model to run trouble free for years. These are $500 new so asking $250. I think home brewers use them for distilling alcohol.