If you have a sewer emergency or serious blockage in your pipes, many times your plumber will need to use the sewer cleanout to deal with the issue. Your sewer cleanout can be located in a lot of different places depending on how your home was built. In places where the temperature often drops low in the wintertime, it is likely located indoors. You can look for it near a bathroom or inside a utility room. A word of warning, however. This is not an access point that you should use if you don’t have experience as a plumber since you could make problems worse.
In warmer climates, you would most likely find the sewer cleanout outside your home, sometimes inside of a box or covered by vegetation. Start by looking near any downstairs bathrooms for a pipe sticking out of the ground. You will usually recognize it by the plastic cap that has a square peg on top.