The minimum depth of filter material under the drain lines of a disposal field shall not be less than how many inches?

The minimum depth of filter material under the drain lines of a disposal field is set at 12 inches to ensure effective filtration and proper drainage. This depth allows for adequate biological activity and prevents the clogging of the drain lines. A sufficient depth of filter material is crucial for supporting the natural breakdown of waste while maintaining proper percolation rates.

If the depth were less than 12 inches, it could compromise the effectiveness of the system, leading to potential issues such as insufficient waste treatment, increased risk of groundwater contamination, and potential system failures. Thus, adhering to the 12-inch requirement helps ensure the longevity and efficiency of the disposal field.