Eljen Pacific | Eljen GSF

Eljen GSF

A42 NSF Logo

Passive Advanced Treatment Technology

  • Third party independent testing data certifies that the Eljen GSF meets NSF/ANSI Standard 40
  • Pretreats effluent with a two-stage biomat
  • Greater long-term performance
  • Requires a much smaller installation area
  • Patented products and technology
  • No stone required
  • Lower site impact
  • Lightweight


When your installation requires extra capacity in less space, the Eljen GSF delivers.  While conventional systems rely on a single biomat forming at the soil interface, the Eljen GSF adds a second, primary biomat layer on the surface of it’s unique Bio-Matt™ Fabric.

How the Eljen GSF System Works


The Eljen GSF Geotextile Sand Filter System is a cost-effective upgrade from other septic technologies.  Comprised of a proprietary two-stage Bio-Matt™ pre-treatment process, the GSF Modules apply a better-than-secondary aerobic effluent to the soil, increasing the soil’s ability to accept the effluent.  The result is a superior treatment in a smaller absorption area.


Primary Treatment Zone

  • Perforated pipe is centered above the GSF Module to distribute septic effluent over and into corrugations created by the cuspated core of the GSF Module.
  • Septic effluent is filtered through the Bio-Matt™ fabric.  The GSF Module’s unique design provides increased surface area for biological treatment that greatly exceeds the Module’s footprint.
  • Open air channels within the GSF Module support aerobic bacterial growth on the Module’s geotextile fabric interface, surpassing the surface area required for traditional absorption systems.
  • An anti-siltation geotextile fabric covers the top and sides of the GSF Module and protects the Specified Sand and soil from clogging, while maintaining effluent storage within the Module.


Secondary Treatment Zone

  • Effluent drips into the Specified Sand layer and supports unsaturated flow into the native soil.  This Specified Sand/soil interface maintains soil structure, thereby maximizing the available absorption interface in the native soil.  The Specified Sand supports nitrification of the effluent, which reduces oxygen demand in the soil, thus minimizing soil clogging from anaerobic bacteria.
  • The Specified Sand layer also protects the soil from compaction and helps maintain cracks and crevices in the soil.  This preserves the soil’s natural infiltration capacity, which is especially important in finer textured soils, where these large channels are critical for long-term performance.
  • Native soil provides final filtration and allows for groundwater recharge.


GSF Module Specifications


For GSF A42 and B43 specifications, click here.

GSF with Tagline

Coming Soon! – New Eljen GSF & Mantis Installation Videos

Detailed step-by-step procedures for traditional applications.

Note: The new videos will feature common installation steps and may not be representative of each county and state’s local code. These videos are a general overview for system installation. Please consult your local regulations for proper sizing and construction requirements.