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What is the Best Soil Type for Septic Systems?



Septic systems are a crucial part of any rural or suburban home that does not have access to public sewer systems. They manage waste effectively, ensuring that the environment remains safe and clean. However, the efficiency of a septic system is heavily influenced by the type of soil in which it is installed.


Understanding what the best soil type for systems is will save landowners future hassles of system failures, poor draining, and costly repairs. Finding the right professionals to assess the soil composition on your land can be challenging. LandGate makes it easy to discover the soil profile of your land with the use of a free property report available to landowners.


Characteristics of a Soil Type for Septic Systems


To install a septic system, first conduct a site evaluation. This evaluation will assess the characteristics of the soil texture and potential drain fields. The suitability of soil particles for a septic system can vary depending on the region and local regulations. Local health departments or environmental agencies typically regulate septic system design installations and may have specific guidelines for soil suitability.


For septic systems a well-drained soil determines the effective wastewater treatment and absorption. The soil structure's ability to filter and treat wastewater is crucial for a septic system to function properly.


In an ideal scenario, the soil should have the following characteristics:

  • Permeability: The soil should have good permeability to allow water to pass through it easily. This ensures that the effluent from the septic tank can be effectively absorbed and treated as it percolates through the soil.

  • Absorption Capacity: The soil should have adequate absorption capacity to handle the volume of wastewater generated by the household. Soils with good absorption properties can effectively treat the effluent before it reaches groundwater or nearby surface water sources.

    • A soil percolation test (also known as a "perc test") is commonly performed to determine the soil's ability to absorb water.

  • Depth to Water Table: The water table should be deep enough to prevent the wastewater from coming into direct contact with it. If the water table is too high, it can lead to the contamination of groundwater sources.

  • Avoidance of Compacted or Clayey Soils: Compacted or clayey soils have poor drainage characteristics and are not suitable for septic systems. These soils can lead to wastewater backups and system failures.


What Soil is Best for a Perc Test?


For a perc test (percolation test), you need a specific type of soil that allows for the effective absorption of water. The purpose of the test is to evaluate how well the soil can absorb water. This evaluation is important in determining whether the soil is suitable for a septic system or other drainage applications. The best soil for a perc test is a moderately permeable soil known as loamy soil.


Loamy soil is a well-balanced mixture of sand, silt, and clay, providing good drainage properties while also retaining some moisture. This type of soil allows water to infiltrate at a moderate rate, making it ideal for the perc test.

  • It balances sandy soil, which drains water quickly, with clayey soil, which drains water slowly and can cause waterlogging. Sandy soil drains water too quickly. Clayey soil drains water slowly and can lead to waterlogging.

During a perc test, a hole is dug in the ground, and it's filled with water to saturate the soil. Then, the rate at which the water percolates or drains away is measured. This helps determine the soil's permeability and its ability to handle wastewater in a septic system without causing environmental issues.


What is the best location for a Perc Test?


You may use LandGate’s data to determine the best spot on your land to perform the perc test. The nationwide soil data allows users to visualize their soil types on their property and estimate where the best location for a perc test and a septic system may lie. Ideally a loam soil type would be best suited for the test and a future septic system. Get your free property report to see what types of soil and where they are located through LandGate.



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