What is the required size for PED lines?

The required size for PED (Pressure-Efficient Distribution) lines being 1.25-1.5 inches with holes spaced 5 feet apart is based on the need for effective and efficient distribution of effluent within an on-site sewage facility. This size range ensures that the lines can handle the required flow rates while minimizing the risk of clogging and allowing for proper distribution across the absorption area.

Using pipes in this size range helps maintain adequate pressure and ensures that effluent can be evenly distributed throughout the soil, contributing to effective treatment and absorption. The specified spacing of 5 feet between the holes promotes even distribution without overwhelming the surrounding soil, which can lead to treatment failures and environmental concerns.

Choosing a size outside of this range could lead to either inadequate flow (if the pipes are too small) or unnecessary complications and costs (if they are too large), impacting the overall performance of the on-site sewage system. Thus, option C accurately reflects the design criteria that balance efficiency, function, and regulatory standards in OSSF design and installation.