How to find the sewer cleanout
A sewer cleanout is a capped pipe or small box on your main drain. Look near the foundation where the line leaves the house, along the route to the street, or indoors near where the drain exits. Find it before a backup, keep it clear, and leave the cap to a plumber.
Sewer cleanout location: where to look first
The cleanout lets a plumber inspect or clear the line without pulling a toilet or opening a wall. That saves time when you're paying by the hour, so it's worth knowing where yours is on an ordinary dry day.
Start where the largest drain line leaves the house, then walk the foundation and the likely route to the street or alley. Common spots include:
- Outside near the foundation
- In the front or side yard, in line with the street connection
- Near the property line, sometimes in a flush box
- Indoors in a basement, garage, crawl space or utility room, often on the main drain before it exits
Look for a threaded cap, a square nut or a round lid on a pipe or fitting. It may be white, black or cast iron. It may stick up slightly, sit flush, or hide under mulch and shrubs. Older homes may have one that's buried, or none that's easy to see.
Three things get mistaken for a cleanout: a vent stack, a floor drain and an irrigation valve box. If you aren't sure what you've found, don't open it.
This matters financially because the pipe is yours. The Insurance Information Institute says homeowners are responsible for the sewer lateral, the line from the house to the city main, including any part under the street. FEMA describes these laterals as usually 4 to 6 inches across and made of clay, cast iron or plastic.
How to find your sewer cleanout, step by step
- Check your paperwork
Look through your home inspection report and any plumbing plans for a marked cleanout.
- Find the main drain
Indoors, look for the largest drain pipe and see which wall it exits through.
- Walk that line outside
Start at that wall and walk toward the street or alley, checking the foundation, then the yard.
- Look under cover
Gently move mulch and light plantings. Don't excavate.
- Confirm what you found
Rule out vent stacks, floor drains and irrigation boxes. Don't open anything to check.
- Record the spot
Measure, sketch and photograph it, then store that with your home records.
- Tell your plumber and insurer
Note the location for the next service call, and ask your insurer what a sewer backup add-on would cost.
Record and protect your sewer cleanout
Once you find it, measure from two fixed corners of the house and add it to a simple site sketch. Take a photo too, with something recognizable in the frame. A city usually won't have this information. Denver, for example, locates only its main sewer lines, so the location of a private cleanout may simply be unknown.
Keep it reachable. Pull back mulch and plants, and avoid building a deck or path over it. Check that the cap isn't cracked or missing, since that opening connects straight to your sewer line.
What to do about a buried sewer cleanout or a backup
If you can't find it, don't probe or dig blindly. Call 811 before any digging, and remember that those locates cover public utility lines, so private lines usually need a separate locate. A plumber can find a buried cleanout or tell you if the house needs one added.
During a backup, leave the cap alone. Loosening it can release wastewater suddenly. Stop using water and call a licensed plumber. The Insurance Information Institute says seepage at a floor drain is an early warning for a plumber, while water coming in fast should be reported to city public works right away.
A bigger line problem is likely if backups keep coming back, or if you notice sewage smells or gurgling across several fixtures. A camera inspection is usually the useful next step. Cracked or root-filled pipe can be replaced with modern material.
If your area floods, ask about a backwater valve. Plumbing permits are required, and you own the upkeep. Some towns help pay. FEMA's guide cites Oak Park, Illinois, which offers a grant of half the cost, up to $3,500. Also ask your insurer about sewer backup coverage, which most companies sell as an add-on.
What homeowners say about finding the sewer cleanout
If the house sat empty for months, watch the lowest drains in your first days of heavy use. One owner's main line had backed up because nothing had been flushed for most of a year. Everything from the main floor came up in the basement until a 75 ft snake cleared it. (Reddit)
What does a sewer cleanout look like, and other questions
What does a sewer cleanout look like?
It's a capped pipe or fitting with a threaded cap, a square nut or a round lid, usually white, black or cast iron. It may sit slightly above ground or flush in a small box.
Is it safe to open a sewer cleanout myself?
Not during a backup, because wastewater can come out suddenly under pressure. If you can't identify the access point with confidence, leave it closed and call a plumber.
Who pays for sewer line repairs under the street?
Usually the homeowner, because the lateral is your responsibility even where it runs into the public right of way. Local rules can differ, so ask your city public works department. Standard coverage varies too, so check your policy.
Sources: denversewerandwater.com, Insurance Information Institute, FEMA
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.