A geotextile filter layer withholds solid components, whilst allowing liquids to pass almost freely perpendicular to the filter plane.
It is differentiated between the mechanical strength (soil retention capacity) and the hydraulic filter effectiveness both with the aim to achieve a water drainage with a minimum loss of pressure.
The requirements can also be fulfilled by a mineral filter. However, geotextile filter layers have proven to be the most suitable and economic alternative.
Like in mineral filter layers, the filter length of the geotextile filters (thickness of the geotextile) can affect the long-term mechanical and hydraulic filter effectiveness. Filters are mainly used in hydraulic engineering and drainage systems.