How to find your main drain?


The main drain of your home is the horizontal line drain that connects your house with the outdoor components of the sewer line. It then connects to the municipal sewer line system or other septic systems that serve homes in your neighborhood.

How to Locate the Main Drain

  1. Follow the path leading from the municipal council’s sewer line up to the exterior walls. Additionally, you can follow direct paths from your septic tanks to the exterior walls for houses without a crawlspace or basement.
  2. A municipality’s or city’s main sewer lines run up to 15 feet underground across the streets and can at times have no visible marks on the ground’s surface. If you have problems locating it check with your municipality or city sewer providers to get its exact location.
  3. The main drain line is usually on the front exterior wall although some houses have additional main drains along their rear exterior walls.
  4. Access your crawl space or basement and locate the drain lines from the sink, bathtub or toilet. Follow them until they connect with the main drain.
  5. At this step, follow the drain line all through the basement until you get to a pipe that makes use of a wye fitting to branch the line.
  6. Search for a flat, white, and round PVC plug on either end of the above-mentioned wye fitting. From the center of the plug, there is a square fitting that protrudes from it. The same plug seals the main drain clean out on its exterior wall. The 3 to 4 inch plug identifies the main drain.

After locating the main drain, home maintenance will be easier to diagnosis. The main drain is the source of many plumbing issues in a home. Finding your main drain is the first step to cleaning and trouble-shooting many drain problems.