The home septic system plays a crucial role in the treatment and disposal of household wastewater. When considering how to conduct maintenance on the septic system, many homeowners do not realize the impact that soil can have on this system. Everything from soil density to texture can affect the system’s ability to complete its job. Without proper considerations for soil type, homeowners may experience unexpected septic breakdowns and septic repairs. A look at how soil types affect the septic system can help you make the right decision for your family.

What Is a Septic System?

A septic system is an on-site wastewater treatment system for the home. This type of system is an alternative for homes that do not use city or municipal sewer systems. The septic system consists of two main parts: the septic tank and the drain field.

Septic Tank

The septic tank is an underground chamber or compartment through which wastewater flows for treatment. Within the tank, solid matter drops to the bottom to form a substance known as sludge. Likewise, lighter waste floats to the top of the chamber to form scum. Once separated, anaerobic bacteria within the tank help break down the organic matter to complete the first course of treatment.

Drain Field

Once the septic tank handles solid waste, the remaining liquid is known as effluent. The effluent flows from the tank into a drain field. Also known as a leach field or absorption field, this area consists of an interconnected network of perforated pipes buried underground. This is the point at which soil plays a critical role in properly dispersing the effluent and disposing of any remaining waste.

What Is Soil?

Soil is a mixture of solid organic matter and minerals. By composition, soil can support everything from plant life to building foundations. In geological terms, soil consists of the following four layers: surface soil, subsurface soil, subsoil, and substratum. Surface soil is the uppermost layer and is what individuals commonly refer to as “dirt.” Also called topsoil, surface soil is mineral-rich and often dark in color due to moisture or decomposing organic matter. Septic systems are almost always located beneath the topsoil.

Subsurface soil is located just underneath the surface soil or topsoil. Septic professionals typically install the drain field in this subsurface layer. Subsurface soil can contain clay or organic materials that move downward due to the percolation of moisture. In other words, water percolates from the subsurface to the topsoil during the normal septic process or water cycle. The final two layers are subsoil and substratum. Subsoil usually consists of clay, silt, or sand. A substratum is a layer of sediment or bedrock above the earth’s crust.

What Is the Morphology of Soil?

Soil morphology refers to its composition and properties. The morphology of the soil determines how a technician can install your septic system and how it impacts the effectiveness of all system components. The two main aspects of soil morphology relevant to septic systems are texture and structure.

Soil Texture

Texture refers to the proportion of differently sized particles within soil. These sizes can affect the ability of soil to drain wastewater. Four main types of textures include sand, coarse particles, fine silt, and clay. Sandy soils naturally have high drainage, coarse soils have good drainage, and fine soils have adequate drainage. Clay soils naturally retain or absorb moisture and therefore have poor drainage. As a result, homeowners who live on clay soil may require additional maintenance and care to avoid septic clogging or backups.

Soil Structure

Soil structure refers to the arrangement of smaller soil particles into large groups called aggregates. The aggregation of soil impacts percolation. In septic science, percolation refers to the ability of wastewater to move downward through porous soil for treatment. The five types of soil structure include granular, block, plate, prismatic, and massive. Experts consider granular soil best for septic systems because the structure supports particle separation and moisture drainage. In contrast, massive structure is a challenging soil type for septic systems since its compacted nature can block the drainage of wastewater.

What Characteristics of Soil Impact Septic Systems?

Different types of soil also have distinct characteristics. These traits impact how the soil can help or harm your septic system. Important soil properties include permeability, density, absorption, and depth.

Soil Permeability

Permeability refers to the extent to which wastewater can transmit or pass through soil. High permeability means that effluent from the septic tank can easily percolate into soil for dispersion and treatment. This helps your system process sewage and prevents the buildup of contaminants or pathogens.

Soil Density

Density describes the compactness of the soil. As the soil gets more compact, it also becomes less permeable. Soil compaction or impermeability soil can reduce the ability of the septic system to absorb, filter, or drain wastewater. This increases the risk of sewage backups or system failures.

Absorption Capacity

Absorption capacity refers to the soil’s ability to handle the volume of wastewater from your household. Soil should be able to absorb and store effluent without becoming overly saturated. Ideal soil mixtures retain wastewater for microbial treatment before it can pollute groundwater or nearby freshwater sources.

Depth-to-Water Table

The depth-to-water table is a measurement of the distance from the bottom of the drain field to the top of the natural groundwater level. This distance is critical for preventing groundwater contamination. If the water table is too high, it can saturate the soil and prevent microbial treatment. If it is too low, the soil will not have enough time to process effluent from the household.

Soil pH

The pH balance of soil can also affect your septic system. Soil that is either too acidic or too alkaline soils can disrupt the lifespan of helpful microorganisms in your system. These microorganisms play a crucial role in treating effluent and prevent waste from polluting the groundwater supply.

What Is the Best Type of Soil for Septic Systems?

According to experts, the best type of soil for septic systems contains a mixture of coarse, granular, sandy, and silty materials. Industry professionals often refer to this combination as “loamy soil.” Having loamy soil is ideal because it strikes a healthy balance between absorption and drainage. The steady absorption gives the system enough time to treat wastewater while the consistent drainage helps prevent sewage backups or groundwater contamination.

How Can I Help My Septic System Work for My Type of Soil?

Due to the vital role that soil plays in septic system performance, it is imperative to reach out to septic or drain cleaning professionals for help with your property. A septic technician can perform soil testing, propose design modifications, and complete regular maintenance to help your system function correctly.

Soil Testing

Soil tests can help determine your soil’s texture, permeability, absorption capacity, and other relevant properties. For example, a technician can conduct a soil percolation test to measure the rate at which your soil absorbs wastewater. Also known as a “perc test,” this evaluation can show how well your system can treat household sewage without causing environmental issues.

Design Modifications

If your soil type is less than ideal, your septic technician may suggest design modifications to protect your property. For instance, if your house sits on highly permeable or sandy soil, your technician may need to create a larger leach field to disperse drainage and ensure that your system has enough time for effluent treatment. If your property is on clay soil, a septic company may need to design special modifications such as aerobic systems or raised mound systems to prevent blockages or wastewater retention.

Regular Septic Maintenance

Regular septic maintenance is essential for preserving the lifespan of your system, protecting the environment, and preventing safety hazards or septic emergencies. The Environmental Protection Agency (EPA) recommends reaching out to a local septic or drain cleaning company to pump your septic tank and inspect the drain field for potential problems.

Contact Us Today

Soil type can greatly affect the performance of your septic system. While the regional soil type may feel outside of your control, septic experts can help ensure that your system works best for your location. Express Septic & Drain Cleaning provides septic services for homes in Nampa, Caldwell, and surrounding areas. We offer essential septic tank pumping, preventive maintenance, and septic system repairs. Our experts can also conduct inspections, tests, and enzyme treatments for optimal performance. Whether you need drain cleaning or suspect a blockage or septic emergency, our technicians can help. Contact Express Septic & Drain Cleaning today for all septic system needs.

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