How to Find Your Sewer Line Cleanout

A sewer line cleanout provides direct access to the main sewer line serving your home. It may be located inside or outside your house and is primarily intended for use by plumbing professionals. If your main sewer line is clogged, or there are signs of a blockage such as multiple backed-up drains, sewage coming from a floor drain, or water backing up in the shower when the toilet is flushed, the cleanout can be used to reach the source of the problem.

What is a Sewer Line Cleanout?

It is a 3-, 4-, or 6-inch diameter pipe leading to the main sewer line. Usually white or black, this pipe is often made of ABS plastic and contains a plug and cap (in older homes, it may be made of brass or cast iron). When opened, it allows access to the main sewage line between the foundation of your home and the municipal sewer system; or, in some cases, between a septic tank and drain piping downstream of the main house trap.

Where to Look

If you live in a colder climate, a standard home often has a drain cleanout inside. However, it may be outside if the house is built on a slab foundation. Sometimes the cleanout is in a garage, utility room, or bathroom. Houses in warmer climates usually have an outdoor drain cleanout. The yard is the first place to look for it.

Finding an Indoor Drain Cleanout

Start by following the drainage pipes that lead from each sink, toilet, washing machine, or dishwasher. These may be made of ABS plastic, copper, cast iron, or bronze. The cleanout is located after where the drainage lines meet the main sewer line. It is usually in the form of a T- or Y-shaped pipe fitting, topped by a threaded plug and square nut possibly covered by a plastic cap. If the drain cleanout isn’t on the main line, then check alternate spots for a fitting with this configuration.

In homes where the sewer cleanout is not on the main line, look in areas where drainage pipes are clustered together, such as a bathroom. Use a flashlight to check in dimly lit areas that aren’t frequently accessed. If you can’t find a cleanout there, look around a utility room or garage. The cleanout may be hidden in homes that have been renovated. Contact a plumber if you’re having trouble locating the sewer line cleanout.

Finding an Outdoor Drain Cleanout

First, walk toward the municipal sewer line or septic tank. The location of the sewer line is indicated by an “S” stamped into the concrete or where the nearest manhole is. The cleanout is typically in line with the septic tank or municipal sewer system. If you use a septic system, walk back towards your home and look for a protruding plastic pipe in your lawn or garden.

If the cleanout is on the municipal sewer line, you won’t see the drainage line. But follow a path through the yard to find the cleanout pipe. It’s usually black or white and sealed with a similar threaded plug and square nut as an indoor cleanout. Check the label as well; it may say “S”, “C.O.”, or “cleanout”. Various types of plastic caps or metal lids may be used so check for anything that may be concealing a 3-, 4-, or 6-inch pipe.

Are you still having trouble finding the sewer cleanout? Look where there are drain pipe clusters or move lawn decorations or foliage outside of bathrooms. You can also try estimating where the drainage line is and poking the ground with a long screwdriver, but you’re better off with a professional’s help.

Contact a Plumber