GeoMat Drainfield System

"What we fear of doing most is usually what we most need to do."

                                                                                                                       Ralph Waldo Emerson 


Todd Kons Trenching - Germantown

4-bedroom mound installed in Washington County


We first introduced GeoMat to Wisconsin in 2017

Since then, over 1500 systems have been installed in Wisconsin without experiencing any failures. 

GeoMat has earned the confidence of soil testers, designers, and contractors throughout Wisconsin. 

While there are nearly as many as there were awhile ago, some people still question the physical

characteristics of GeoMat. Other people do not believe in downsizing. We will do our best to

answer these and other questions anyone might have


Before you can solve a problem, you have to find out what's causing it.

Septic systems fail because the soil has become saturated with wastewater

Saturated soil causes oxygen starvation, which stops the flow of air into the ground, which creates

anaerobic bacteria. Anaerobic bacteria produce a jelly-like permeable substance just below the

surface of drainfield trenches.


As long as the ground is wet, anaerobic bacteria will multiply and biomat will cover more drainfield

  • The domino effect created by bacterial growth will continue until the entire drainfield covered by biomat.

  • When this happens, wastewater surfaces above the ground and/or backs up into the house.

  • At this point, the septic system has failed and has to be replaced.


Septic system lifespan is largely determined by water usage

  • Not only how much water is used, but when it is used.

  • If the daily water usage regularly exceeds the capabilities of the system, it will shorten the lifespan.   

  • Large amounts of water used in short time periods of time will also exceed capabilities and shorten lifespan.

      (See ClearFlow Filter/The Problem With Effluent Filters)​

Gravity systems only utilize a small portion of the drainfield at any one time. 

When one area becomes saturated and covered with biomat, water flows to the next open area. The cycle

is repeated until the system fails. How long it takes depends upon the quality of stone and water usage. 

Pressurized systems disperse water more evenly than gravity but...

Pressurized systems disperse water from end to end, but they do not disperse effluent evenly from side to side. The

most common cause of failure in mound systems is due to biomat forming at the interface of the orifices and the sand. 

When mounds are dug up, the outer area is completely dry. 

There are two primary reasons why this occurs

1.  Hydraulic jetting of the underlying soil; the system is not designed to disperse water away from the point of contact. 

     This situation becomes even more problematic if the system is over-dosed because the floats are set incorrectly. 

2.  Lateral orifices becoming plugged from the inside out. 

     Unless the septic tank is pumped prior to removing an effluent filter, solids will flow through the bottom of the filter case 

     into the pump chamber. A completely plugged filter creates double jeopardy because all the fats, oils, and grease       

     floating above the top of the case will flow out along with solids going out the bottom of the case.


     Any debris that reaches the pump chamber will pass through the pump into the distribution laterals. When the pump 

     shuts off, the debris is going to settle on the bottom of the pipe where it will plug orifices creating uneven distribution.            Some areas will get more water than the ground can handle resulting in saturated, oxygen-starved conditions; the

     perfect environment for creating anaerobic bacteria that produce biomat. As long as the soil remains wet, biomat

     will cover more ground.


The solution is utilizing more area with each dose

Shallow burial depth + even dispersal of water = maximum oxygen transfer

  • Burial Depth            GeoMat is buried 12" below the surface of the ground.

  • Even Dispersal        The shape and entangled plastic membrane spread water across the entire mat. 

  • Oxygen Transfer      Anaerobic bacteria can not exist in a dry, aerated environment. 

The Mechanics

  • ​The wide surface area and thin profile allows water to quickly travel through the sand,

       resulting in different levels of the sand being saturated only briefly, if at all.​


The Result

  • GeoMat utilizes the entire leachfield every time it doses.

​​The Proof 

  • GeoMat 2.0 load rate and hydraulic capacity were proven in stringent NSF testing.                         

  • When a proprietary system is independently tested by NSF, the leaching system is

       hydraulically loaded at the design loading rate every day.

  • The design loading rate used to load the leaching  system includes a peak flow, which

       includes a safety factor typically between 1.5 to 2 times the actual rate. In addition,

       the NSF regime requires a high flow stress test be performed. 

  • The loading rate applied under NSF testing protocol should never happen in the real world.

GeoMat Dimensions

  • GeoMat is 39" wide x 1" thick

  • It comes in a 100' long roll

  • One roll is 36"x36"x43" high. 

  • A roll weighs 70 pounds

  • Easily fits in a pickup

GeoMat is approved in Wisconsin for the following applications                  

  • Conventional gravity systems                                                                        

  • Conventional dosing systems                                                                           

  • Conventional pressurized systems

  • Regular mound systems

  • Split-bed mound systems

Wisconsin Component Manuals

GeoMat Mound Component Manual: Revised in 2020 (Click to download)

GeoMat Inground Component Manual (Click to download)

GeoMat Inground Filter Revision Approval from DSPS (Click to download)

Lineal Feet

Three bedrooms require 70 lineal feet

Four bedrooms require 92 lineal feet


System Length

  • Three bedrooms require 70 lineal feet

  • Four bedrooms requires 92 lineal feet

  • No wasted material. GeoMat sections can be spliced together by placing a piece of

      fabric across the two sections and tucking it underneath the GeoMat on each side.

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Side by side comparison:  4-bedroom mound 


Below: Brian Gundy Septic Systems, Minocqua

Two bedroom inground pressure system installed in Oneida County

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