Leach Field Chambers – Pros, Cons, Functions & Installation

If you operate a septic system, one of the components of the system is the leach field chamber.

This wastewater treatment system comprises beds or trenches which are built or constructed on appropriate soil types for wastewater filtration. Septic systems are made up of four parts.

These parts include the primary drain line that connects to your home’s plumbing system, the septic tank, the distribution box, as well as the leach field also called the drain field.

The last component (the leach field) is where most of our focus will be.

Functions of Leach Field Chambers

The functions of leach field chambers are two-fold; for effluent disposal from septic tanks, as well as for distribution of effluent for onward treatment in the soil.

In simple terms, the leach field chamber is a wastewater treatment system that consists of beds or trenches which include open-bottomed plastic or distribution pipes.

These are placed in the right type of soil to distribute wastewater for onward filtration.

Of course, the wastewater being distributed from the leaching chamber is received from the septic tank. This is a repeated process that occurs with proper functioning required.

  • Multiple Leach Field Chambers May be Installed

When it comes to the installation of leach field chambers, the size of the drain field comes into play.

In some cases, a single leach field chamber will suffice, while for others, multiple chambers will need to be installed to form the underground drain field network.

  • Leach Field Chamber Material

Leach field chambers are mostly made from multiple high-density polyethylene materials. These chamber segments are injection-molded and have an arch-shaped appearance.

On average, the inside width of a leach field chamber is about 20 to 40 inches with a length between 6 to 8 feet.

  • Pros of Leach Field Chambers

Leach field chamber systems offer many benefits compared to their gravel drain field counterparts.

With leach field chambers, you have a system that’s easier and faster to install. Plus, soils within the trenches aren’t likely to compact.

With leach field chambers, you get greater storage volumes compared to gravel beds or trenches, thus eliminating the need for gravels. Also, chamber inspection tends to be much easier.

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This is in addition to extending the useful lifespan of the drain field.

  • Cons of Leach Field Chambers

Ideally, leach field chambers will serve best in areas without gravel or where gravel supply is short.

However, with an abundance of gravel, leach field chamber installation becomes more expensive as gravels offer a cheaper alternative to leach chambers.

In terms of filtration efficacy, leach field chambers tend to have some level of disadvantage in some soils.

Groundwater pollution could occur with this type of filtration system.

Key Considerations Before Leach Field Chamber Installation

Before a leach field is chamber is installed, several factors are taken into consideration.

These include the soil type, site topography as well as groundwater level. All of these factors support the proper functioning of the leach field chamber.

Let’s briefly take a look at each.

i. Soil Type

Soil type is crucial for leach field construction. Such soils need to have the right structure, texture, as well as drainage for wastewater to be properly filtered.

Wastewater needs to be safe enough to rejoin groundwater and the soil type is crucial towards achieving that.

  • Right Structure

A soil structure might be affected by multiple conditions ranging from wetting & drying as well as freezing and thawing. These are constant changes that shape the soil structure making it permeable enough for downward movement of water and air.

The soil being used for leach field chamber construction should have sufficient and interconnected pores and spaces for proper drainage of wastewater.

  • Right Texture

Also, soils used for leach field chamber installation should have the right texture. So, what’s the right texture?

Basically, this has to do with the soil composition in terms of the amount of sand, silt, and clay present. You don’t want to use heavy soil (with lots of clay), or one that’s less porous (having lots of silt).

At best, the right soil structure for leach field chamber construction should be balanced. That is, not having too much clay or silt.

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The most ideal soil for leach field installation is one having a balance between gravel and clay.

  • Proper Drainage

As the name implies, this has to do with the soil’s drainage capacity. Poor draining soils are mostly avoided when it comes to leach field chamber construction. Depending on other conditions, certain modifications may be made.

ii. Site Topography

Because topography is crucial to wastewater percolation, a steep slope won’t allow even the best soil to adequately drain or percolate.

Site topography mostly determines water flow which is crucial to on-site system placement and functioning.

There are varieties of compositions when it comes to site topography.

They include linear-linear, linear –convex, linear-concave, and convex-linear. Others include convex-convex, convex-concave, concave-linear, concave-convex, and concave-concave.

All of these are considerations are looked into before deciding whether the site has the right topography and landscape position for building a leach field chamber as well as the septic system.

iii. Groundwater Level

The groundwater level is vital to leach field chamber construction.

The leach field chambers should be at the right elevation to allow for proper filtration of wastewater. You want to avoid groundwater pollution at all costs as it has consequences.

Acceptable or Setback Distances for Leach Field Installation

Whenever leach field chambers are installed, adequate distances must be maintained with water supply among other things. To be more specific, a minimum of 25 feet distance should e maintained with an open ditch or stream.

For public water supply wells, such distance should be a minimum of 300 feet.

Private water supply wells can maintain a 100 feet distance, while sewer interceptor drains should have a setback distance of 25 feet from the leaching chamber.

For water lines under pressure, a 10 feet distance is acceptable. The same applies to property lines.


So far, we’ve looked at leach field chambers and the different aspects of their operation. This is part of an onsite septic treatment system that’s widely used.

Your septic technician should advise on what best serves your needs.

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