We sell filters with a strong pathogen reducing function, which is partly due to the high pH of the material that kills bacteria. High porosity of the filter material adsorbs, and “lock up”, bacteria which therefore die. In addition, at lower pH competing good bacteria forms on the filter material, which partly kills and knocks out the harmful bacteria. New filters has such high pH that the bacterial reduction is essentially complete. Older filter mass (roughly said with a pH below 10) still has a very good bacterial reduction, mainly through the lock-up mechanism.