What is used in a leach field to prevent fine soil particles from migrating into the gravel?

In a leach field, the main purpose is to allow treated wastewater to be absorbed into the soil, where it can be naturally filtered and further treated by soil microorganisms. To prevent fine soil particles from migrating into the gravel, maintaining the integrity of the filtration system is essential. Utilizing materials like paper or straw serves as a natural barrier that can effectively filter out these fine particles while allowing water to flow through.

Paper or straw can act as a filter layer atop the gravel, providing a physical barrier that reduces clogging of the gravel, ensuring the efficient and effective drainage of wastewater. This helps maintain the leach field's functionality by allowing water to move freely into the gravel while still filtering out the smaller particulates that might disrupt the flow and clog the system over time.

Other options, such as cloth or plastic, may not always provide the optimal filtration and permeability characteristics needed in a natural system like a leach field, whereas the organic nature of paper or straw contributes positively to the filtration process while also potentially decomposing over time and further enriching the soil.