Gravel less effluent disposal septic system - image of the gravelless chamber system design is courtesy US EPA, originally from National Small Flows Clearinghouse Gravelless Septic Systems

  • GRAVELLESS SEPTIC SYSTEMS - CONTENTS: Design manual for gravelless or no rock septic fields, No-rock or chamber septic drainfield product descriptions, sources, Septic leaching field product cost comparisons, Septic absorption field capacity & life comparisons
  • POST a QUESTION or READ FAQs about no-rock or "gravelless" Septic Systems - Design, Inspection, Testing, & Maintenance
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Gravelless septic field designs:

This article series discusses the design, product alternatives, life and cost of several types of gravelless or "no gravel" or "no rock" septic drainfield systems, offering installation specifications and a list of product suppliers.

Septic drainfields, also called leach fields, absorption beds, soil absorption systems, soakaway beds, and leaching beds, perform the functions of septic effluent treatment and disposal in onsite wastewater treatment systems, conventionally called "septic systems".

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Gravelless Systems - Gravelless Septic Absorption Systems

Gravelless septic systems or "no gravel" septic system trenches use plastic or other prefabricated wastewater distribution systems which are buried in soil without the use of surrounding gravel.

Typical gravelless septic systems use a plastic chamber, a geotextile-wrapped pipe, or a polystyrene-wrapped pipe to distribute effluent into the soil. The necessary soil absorption area is provided by the perforated surface of the gravelless septic system components (or by soil at the bottom of a chamber) themselves rather than by the gravel and trench walls of a conventional septic drainfield.

Gravelless septic drainfield systems can provide an acceptable effluent disposal system for sites with limited space for a drainfield or where gravel is not available or is quite expensive.

Article series content

Three Basic No-Rock Gravelless Septic Absorption Field Products / Designs

There are three typical gravel-less effluent disposal systems in current use and shown in the US EPA sketches below (originally from NSFC) and just below we describe a fourth variation which is provided by some manufacturers:

  1. GRAVELLESS SEPTIC POLY-WRAPPED PERF PIPE (no product sources found)
  4. 8" foam-block absorption field design (discussed below)

    for gravelless or "no-rock" septic designs for effluent disposal or soil absorption beds

Use of Polystyrene-wrapped perforated pipe for Septic Effluent Treatment/Disposal Fields

Gravel less effluent disposal septic system - Polystyrene-wrapped perforated pipe - image courtesy US EPA, originally from National Small Flows Clearinghouse
Polystyrene-wrapped perforated pipe buried in an earthen trench.

Note: We have been unable to find websites listing this product.

Companies offering this product are invited to add your listing here - no fees are involved: manufacturers of alternative effluent disposal systems are welcome to list their product lines and websites here at no fee. CONTACT US

8" Pipe & Foam Block Drainfield Design: (not the sketch at left)

We have also read a proposed drainfield design using an 8" diameter pipe, perforated only on the bottom, placed in a trench surrounded by recycled foam blocks. That design raises some troublesome questions:

    • What is the life expectancy of a pipe and foam block septic drainfield?
    • What keeps soil from clogging the foam blocks
    • How does effluent treatment or disposal benefit from blocks placed higher than the pipe bottom perforations?
    • What is the cost of excavating to replace the foam blocks?

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