Drainlayer Tradesman Practice Exam 2026 - Free Drainlayer Exam Practice Questions and Study Guide

Grease interceptors are designed to keep fats, oils, and grease from entering the sewer system. In a kitchen drain setup, wastewater passes into a larger chamber where lighter fats and oils float to the top, forming a grease layer, while heavier solids settle at the bottom. Water near the middle then exits to the sewer, but the accumulated grease and solids stay in the interceptor until they’re pumped out. This separation protects plumbing and municipal sewers from clogs, backups, and odor.

This isn’t about heating the water, filtering only solids, or adding air to the wastewater, so those options don’t fit the purpose of a grease interceptor.