Which of the following statements about porous media in a standard drainfield is true?

The correct statement about porous media in a standard drainfield is that it should be 0.75 to 2 inches in size. This size specification is important because it facilitates adequate water flow and ensures effective filtration. A properly sized porous medium allows for optimal drainage and aeration within the system, which is necessary for the breakdown of organic matter and the prevention of clogging.

Adequate sizing helps maintain the balance required for the microbial processes that treat wastewater. If the size of the particles in the porous media is too small, it could result in compaction and restricted water flow, while larger particles may not provide enough surface area for bacteria to thrive.

The other statements can mislead regarding the characteristics of porous media in a drainfield. While porous media can vary in size, the focus on a specific range is crucial for functionality. Saying it must be dirty does not align with proper filtration principles, as clean media are essential for effective water treatment. Lastly, compacting the media tightly contradicts the need for sufficient space for water movement and microbial activity, which is critical for a healthy drainfield operation.