Which action is NOT part of constructing a greywater disposal field?

The construction of a greywater disposal field involves various components aimed at efficiently managing and dispersing greywater, which is relatively clean wastewater generated from domestic activities, excluding toilet waste. The options presented relate to techniques typically employed in constructing such systems.

Using additional filter materials, employing stone and gravel for filtration, and creating a septic leach field all correspond to standard practices in greywater disposal. Additional filter materials can enhance the treatment process by trapping solids and allowing for better filtration before the water enters the ground. Stone and gravel play a crucial role in promoting drainage and aeration, making them essential for effective greywater dispersal.

The correct answer revolves around providing backfill over filter material. This practice is typically associated with traditional septic systems rather than greywater disposal systems. Backfill is used to cover septic systems, but greywater systems focus primarily on the dispersal of treated water through gravel and stone, which allows for natural filtration and absorption into the soil without the need for heavy backfilling. Thus, providing backfill does not align with the standard practices for constructing a greywater disposal field.