Illinois Septic Installers Practice Exam 2026 - Free Septic Installer Practice Questions and Study Guide

The use of perforated pipe or OJ tile in gravel systems is correct because these materials are designed to facilitate the effective drainage of wastewater within the septic system. Perforated pipes allow effluent to seep through holes along their length, enabling the liquid to distribute evenly throughout the gravel, which helps in the filtration and absorption process. The gravel acts as a natural filter, allowing microorganisms to break down contaminants. This combination ensures that wastewater is adequately treated before it reaches the surrounding soil.

Concrete pipes, rigid plastic, and fiberglass are not typically chosen for use in gravel systems due to their solid construction, which does not provide the necessary openings for distribution and infiltration that perforated materials do. Choosing the correct type of piping is crucial for the efficiency and functionality of a septic system, ensuring that it operates effectively and minimizes environmental impact.