All gravelless drainfield pipes must be encased with what feature at the point of manufacture?

The requirement for all gravelless drainfield pipes to be encased with a filter wrap at the point of manufacture is essential for ensuring proper filtration and protection of the system. This filter wrap serves a critical role in preventing soil particles from clogging the pipes, while still allowing for the effective passage of effluent.

The filter wrap is designed to meet specific characteristics that are conducive to the conditions of septic systems, enhancing the performance and longevity of the drainfield. It helps maintain the permeability around the pipes, ensuring that water can move away from the drainfield efficiently, which is paramount for the overall health of the septic system.

In contrast, options such as concrete casing or standard soil material would not provide the necessary filtration and might lead to issues like sediment accumulation and reduced efficiency. Flexible plastic casing does not offer the same level of support and filtration that a filter wrap provides, making it less suitable for encasing these types of drainfield pipes.