Step 5 · Inspect Main Sewer Line Cleanout

This is the step most people slow down on. Take it one move at a time — there’s no rush, and you can rewind the clip as many times as you need.

If you have cleared the vent stack and the gurgling persists, the final DIY step is to check if the problem is in the main sewer line. This is mainly a diagnostic step. If you determine the main line is clogged, you must call a professional. Locate your main line cleanout, a 3- to 4-inch pipe with a cap, typically found in the basement, crawlspace, or outside in your yard near the foundation. Place a bucket underneath if it's indoors. Wear safety glasses and gloves. Using a pipe wrench, slowly and carefully unscrew the cap. Be prepared for potential sewage backflow. Once open, look inside with a flashlight. If you see standing water or it's full of wastewater, the clog is in the main line between the cleanout and the street. If it's empty and dry, the clog is somewhere between the bathroom fixtures and the cleanout.