When classifying water treatment equipment, there are two different standards in the water filter industry.
Log 4 reduction refers to the removal of at least 99.99% of pathogenic bacteria. This is may be called a water filter.
Log 6 reduction refers to the removal of at least 99.9999% of pathogenic bacteria. When combined with a reduction in viruses by at least 99.999% (log 5 reduction) you have a water purifier.
All Berkey systems that run on Black Berkey purification elements are classified as water purifiers. Berkey Water Purifiers go above beyond the water filter industry standard and attain a log 9 reduction of 99.9999999% removal of pathogenic bacteria. To the best of our knowledge no other water filtration/purification device in the world can match this claim.
As most people search for water filter or purification systems on the internet with search terms such as water filter, water filters or water filtration, we use the terms filter/filtration and purifier/purification interchangeably on our website when discussing Berkey Water Purification Systems. Anytime we use the term filter/filtration in respect to the Black Berkey element or Berkey Water Purification Systems we are always really signifying purifier/purification.