text: When a septic tank is used in combination with a biofilter, the height and catabolic area of the drain field may be reduced.  Biofilter technology may allow higher density residential construction, minimal site disturbance and more usable land for trees, swimming pools, or gardens.  With adequate routine maintenance it may reduce the chances of the drain field plugging up.  The biofilter will not reduce the volume of liquid that must percolate into soil, but it may reduce the oxygen demand of organic materials in that liquid.