Sewer cleanout: what it is, where to find yours, and what if there isn't one
Updated
The short answer
A sewer cleanout is a capped pipe that gives direct access to your main sewer line, so it can be cleared or camera-inspected without pulling a toilet or digging. Look outdoors within a few feet of the foundation, near the property line, and indoors where the main drain leaves the basement or crawl space. The cap is a round plug with a square nub.
How urgent · It depends
Finding it isn't urgent — until the main line clogs. Locate it now, while nothing is wrong, so you and a plumber aren't searching for it during a backup.
Health & safety
If drains are backed up, the pipe behind a cleanout cap can be full of sewage under pressure. Loosen a cap slowly, a little at a time, wearing gloves and eye protection, with a bucket ready and your body to one side — and don't open an indoor cleanout on a full line at all.
What a sewer cleanout does
Every sewer line eventually needs clearing or inspecting, and the cleanout is the door. It's a short vertical pipe, usually 3 or 4 inches across, that tees into the main sewer line and rises to the ground surface or the basement floor, closed with a threaded plug.
With a cleanout, a plumber can feed a drain cable, a jetter hose or a camera straight into the main line in minutes. Without one, they have to go in through a roof vent or remove a toilet, which takes longer, costs more and reaches the line less effectively.
Where to find your sewer cleanout
Plumbing codes require a cleanout near the point where the building drain inside becomes the building sewer outside, brought up to finished grade or the basement floor, so that's where to look first.
- Walk the outside of the foundation, especially on the side nearest the bathrooms and the kitchen, and on the side facing the street. Look for a capped pipe a few inches above the ground, or a small ground-level box with a lid.
- Check near the property line or the front of the lot. Many homes have a second cleanout there, and some cities require one.
- Look indoors where the main drain leaves the house: in the basement or crawl space near the wall facing the street, in a utility room, a garage, or near a floor drain.
- Check under bushes, mulch and grass along that side of the house — cleanouts are often buried by landscaping or cut down flush with the lawn.
- Ask the previous owner, a neighbour with the same house design, or look for a previous plumbing invoice or sewer scope report, which usually notes the access point.
- Still can't find it? A plumber can send a camera with a transmitter in through a vent or a toilet and locate the line and any buried cleanout from above.
What a sewer cleanout looks like
- A white or black plastic pipe with a threaded cap that has a square or hexagonal nub on top for a wrench — the most common modern cleanout.
- In older homes, a cast iron fitting with a brass or iron plug, often in the basement on the main drain.
- A small round or square ground box with a metal or plastic lid, used where a cap would be hit by a mower.
- A two-way cleanout: two caps side by side, or a single cap over a fitting that opens toward both the house and the street.
- Not to be confused with an irrigation box, a gas or water meter, or a septic tank riser — those have different lids and are often labelled.
Where cleanouts are required
Most US jurisdictions adopt a version of the International Plumbing Code or the Uniform Plumbing Code, with local amendments, so details vary. The International Plumbing Code, for example, requires cleanouts:
- Near the junction of the building drain and the building sewer, inside or outside the wall, brought up to finished ground level or the basement floor.
- On building sewers at intervals of not more than 100 feet.
- At each change of direction greater than 45 degrees in the building sewer and building drain (with some relief where several bends occur close together).
- At the base of each vertical soil or waste stack.
One-way and two-way cleanouts, and what they cost
A one-way cleanout opens toward the street, which covers most clogs. A two-way cleanout opens in both directions, so a plumber can also reach the section back toward the house without going through a fixture — worth the extra when the line is being dug up anyway.
| Job | Typical cost |
|---|---|
| Install a one-way cleanout | About $650 – $2,000 |
| Install a two-way cleanout | About $1,400 – $3,500 |
| Replace a broken or missing cap | A few dollars to about $30 for the part; a quick plumber visit otherwise |
| Raise a buried cleanout to grade | Usually a small job; depends on depth and surface |
Installation ranges from Angi and plumbing contractor cost guides (2026). Depth, distance to the line and concrete over it drive the price.
What if your house doesn't have a cleanout?
Older homes often don't. It isn't a defect you have to fix immediately, but every clog becomes more expensive and slower to clear, and some jobs — camera inspections, jetting, lining — are much harder without one.
Installing a cleanout pays for itself after a couple of main-line calls, because a plumber can then clear the line from outside in a short visit. The ideal time is whenever the line is being dug up for another repair.
Common cleanout problems
- A cracked or missing cap: an open pipe into the sewer lets in rainwater, debris and pests, and lets sewer gas out. Replace it.
- A cap cut down by a mower or buried under a new patio: have it raised or fitted with a ground box.
- Rainwater or yard drainage directed into a cleanout: most cities prohibit it, because it overloads the sewer.
- Sewage coming out of the outdoor cleanout: the line is blocked downstream of it — stop using water and call a plumber, or the utility if neighbours are affected.
- A seized plug: don't force it with heat or a hammer on old cast iron; a plumber can cut and replace it.
Frequently asked questions
- What is a sewer cleanout?
- A capped access pipe connected to your main sewer line, usually 3 or 4 inches across, that lets a plumber clear or camera-inspect the line without going through a toilet or roof vent.
- Do all houses have a sewer cleanout?
- No. Newer homes almost always do, because plumbing codes require one near where the building drain meets the building sewer, but many older homes were built without one or had it buried by landscaping.
- Where is the sewer cleanout located on a house?
- Usually outdoors within a few feet of the foundation on the side facing the street or near the bathrooms, sometimes near the property line, and indoors on the main drain in a basement, crawl space, utility room or garage.
- How far is a sewer cleanout from the house?
- Typically within a few feet of the foundation, because codes require it near the junction of the building drain and building sewer. A second cleanout may sit near the property line.
- What does an old sewer cleanout look like?
- Often a cast iron fitting on the main drain in the basement, closed with a square-headed brass or iron plug. Outdoors, older cleanouts may be cut flush with the ground or buried under lawn and landscaping.
- How much does it cost to install a sewer cleanout?
- About $650 to $2,000 for a one-way cleanout and $1,400 to $3,500 for a two-way cleanout, depending on depth, distance to the line and what has to be dug through.
- How do you unclog a main sewer line without a cleanout?
- A plumber can feed a cable or camera through a roof vent or by removing a toilet and going in through the floor flange. It takes longer and costs more, which is why many people install a cleanout afterwards.
- Can I replace a sewer cleanout cap myself?
- Usually, yes — caps are inexpensive and thread in by hand or with a wrench. Match the size and type, and don't open the cleanout while drains are backed up.