How to Find Out Where Sewer Lines Are Placed Outside a Home

The tricky thing about plumbing is that you usually can't see it. You know the sewer pipes are out there somewhere, draining waste water from your home to the sewer system, but you don't know exactly where they are. As a homeowner, it is important that you know how to locate your sewer pipe. If there's a problem with the pipe, you need to know where to dig to expose it. Also, you also wouldn't want to dig a pond or pool and accidentally knock a hole in your sewer line.

Sewer pipe may be located under walkways.

Things You'll Need

  • Pipe wrench

  • Plumbing snake

Step 1

Visit your city planning or property permit office and get a copy of the plumbing permits that were obtained at the time your house was built. Notice the attachments to the permit -- there will be a rough drawing of your lot, your home and the approximate location of the sewer pipe that connects your home to the city sewer system. Purchase a copy of these documents for a minimal fee at permit office. Go back home with the rough drawing to determine approximately where your sewer pipe is located.

Step 2

Hire a plumbing professional to help you determine where your sewer pipe is, if you can't figure out the drawing from the permit office or if you weren't able to get a copy of the permits. The plumber will find the sewer cleanout valve, which is usually located close to the exterior of the house, near a bathroom. The plumber will remove the valve lid and scope the sewer by running a flexible metal snake down the sewer pipe. The snake has a small light and camera attached to its tip, and it takes video footage of your sewer pipe as it goes along. When the plumber finishes the scoping project, you will get a video of the entire scope, showing how many feet away the scope is at various points in the sewer line. A sewer scope is the most expensive way to locate your underground sewer pipe, but it is also the best way to be certain exactly where your pipe is.

Step 3

Locate your sewer pipe on your own, if you prefer. Find the sewer clean-out located outside your home at ground level, usually close to an interior bathroom. Use a pipe wrench to remove the lid of the sewer clean-out. Insert the end of a plumbing snake into the pipe as far as you can. Pay close attention to when the snake bends or drops as it makes its way through the pipe, and track the length of the snake as you go. This will give you a very good idea of where the sewer pipe on your property is located.


If you have to expose the sewer line on your property, start digging near the clean-out valve and follow the pipe as you expose it.


Check with your utility company before you dig to make sure there are no buried cables or utility boxes on your property that you could damage while you are trying to find your sewer line.