How to Locate My Main Drain Clean-Out

Cecilia Harsch

If you are unable to unclog your sink or toilet using a plunger or sewer snake, the clog could exist somewhere along your main drain line. You must access your home’s main clean-out to remove or flush the clog from the line. Locating your main clean-out could be difficult if you do not know where to look.

  1. Follow a path from the main city sewer line up to your home’s exterior wall or follow a direct path from your septic tank to you exterior wall for dwellings without a basement or crawlspace. A city or municipality’s main sewer lines usually run 8 to 15 feet deep under the street. Check with your city or municipality regarding the exact location of the sewer line on your street. The main drain clean-out is along the front exterior wall. You may have an additional main drain clean-out along the rear exterior wall.

  2. Access your basement or crawl space. Locate a drain line from a toilet, sink or bathtub and follow it until it connects with the main drain line. Follow the main drain line under the floor until you come to a pipe that uses a wye fitting to branch off the line.

  3. Look for a flat, round steel or white PVC plug on one end of the wye fitting. A square fitting protrudes from the center of the clean-out plug. This same plug covers the main drain line clean-out along the exterior wall. It is this 3-or 4-inch plug that identifies the main clean-out.