Which drainage material is appropriate for a standard drainfield installation?

The appropriate drainage material for a standard drainfield installation is uniform porous media. This is because uniform porous media, such as specifically graded gravel or sand, facilitates effective drainage and aeration, which are crucial for the function of a drainfield. The uniformity ensures consistent voids that allow wastewater to move through the media easily and promotes the biological treatment process by providing oxygen to the microorganisms that break down contaminants in the wastewater.

In contrast, crushed concrete may not provide the necessary drainage characteristics. While it can allow for some water flow, the irregular shapes can create areas where water pools rather than drains efficiently. Gravel only, though traditionally used, may not always meet modern engineering and regulatory standards for uniformity and size, which can affect drainage performance. Silty soil is unsuitable because it has fine particles that can compact and limit permeability, leading to drainage issues and poor wastewater treatment.