Clay sewer pipes carry waste water away from your house to the city's main sewer line. These pipes are buried underground. If you just moved into the home or if you've never had trouble with your sewer lines, you may not know where they are located. Should you need to dig them up or just want to know where they are, you can locate clay sewer pipes without having to dig up your entire yard.
Inspect the roof of your house for the sewer vent, usually located above your bathroom or kitchen. Line the sewer vent with the outside cleanout line. Once these two points are lined up, site a straight line out to the alley.
Locate the sewer line where it exits through the side of your house. This line will be in the basement or crawlspace under your home. Make a metal note on where this pipe is located outdoors or measure the distance straight across from a window or doorway. Go outdoors and transfer those measurements from the window, door or wall. Place a flag over the area where the sewer line leaves your home. Find the person in charge of your city's maintenance department who can tell you where your sewer pipes connect to the city line. This is the location of your sewer pipes. Line up these two points and your sewer will be underneath.
Douse for the sewer lines, using a willow rod or two welding rods. (This is also called water witching.) Bend one end of each rod at a 90-degree angle for a short handle. Hold the welding rods by the handle and walk around your property where you believe the clay sewer line is located. The rods will cross over each other, making an "X" when you are over a sewer line or other water line.
Examine the infrastructure map located in your city's sewer department. This map not only gives you the location of your clay pipes, it also tells you the depth.
Contact a plumbing service that has a sewer camera. This special camera can be sent down through the sewer system, revealing the location of your clay pipes.