Which specification has a lower water holding capacity in septic systems?

Coarse sand media has a lower water holding capacity compared to the other options listed. This is primarily due to the size and structure of the grains in coarse sand, which allows for larger void spaces between the particles. These larger spaces facilitate quicker drainage, leading to reduced water retention within the media.

In septic system applications, coarse sand is often selected for its ability to promote effective drainage and prevent waterlogging, which can impede the treatment process. The quicker movement of water through the coarse sand results in less accumulated moisture, making it less effective for holding water compared to regular sand media, ASTM C-33, or gravel media, which retain more water due to their finer particles and varied particle sizes that create tighter spaces.

Understanding these characteristics informs better choices in designing and installing septic systems, ensuring effective effluent treatment and environmental protection.