Ammonium can be a sign of microbacteriological activity in the water and can be a result of fertilization, contamination, or it can be geologically conditioned.
Ammonium is transformed into nitrite and after this into nitrate by a biologically conditioned nitrification process.
The process calls for a great oxygen demand and sufficient filter material consisting of quartz sand or a porous calcium-based filter material.
The ammonium content of the drinking water can be reduced by means of a biological process, in which ammonium is transformed into nitrate via nitrite. The process calls for thorough knowledge about correct water treatment.