Where are sewer cleanouts required by code?

Phoenix builds and inspects to the 2024 Uniform Plumbing Code (UPC), and the cleanout rules in Section 707 line up closely with IPC Section 708 used elsewhere. Four required locations cover almost every home and small commercial drain system.

The first is near the junction of the building drain and the building sewer. This is the point where the pipe under or beside your house hands off to the line that runs out to the public main. It is the natural starting point for clearing the whole lateral, so the code wants an opening there.

The second is a spacing rule. On the building sewer, cleanouts must sit at intervals of not more than 100 feet. A snake or jetter hose can only reach so far before it loses push, so a long run gets broken into reachable segments. A short suburban lateral may need only one or two; a deep lot can need several.

The third covers turns. The code requires a cleanout at each aggregate horizontal change of direction greater than 135 degrees. "Aggregate" means the code adds up the bends between cleanouts, so two 70-degree elbows close together count as 140 degrees and trigger the requirement. Sharp and stacked turns are exactly where debris snags, and a cleanout at the bend gives a tool a way around the corner.

The fourth is vertical. A cleanout belongs at the base of each waste or soil stack, the vertical pipe that carries waste down from upper-floor fixtures. Material falling down a stack lands hard at the bottom elbow and tends to pack there, so an opening at the base lets a plumber reach that low point.

A few other spots come up on larger or older systems. Many designs also call for a cleanout at the upper end of a long horizontal drain run, so a tool can be fed downhill with the flow. Where a building drain leaves the structure, an outside cleanout brought up to grade near the wall is common, since it lets a plumber work the line without entering the home. The exact wording and any local change live in the adopted code and the Phoenix amendments, so a permitted job is laid out to match what an inspector will check.

Size is tied to the pipe it serves. The rule is that a cleanout is the same nominal size as the pipe it serves, but it need not exceed 4 inches. So a 2-inch line gets a 2-inch cleanout, a 3-inch line gets a 3-inch one, and any pipe of 4 inches or larger still only needs a 4-inch cleanout.

That ceiling is practical. Most drain-clearing tools, cables, and camera heads are built to pass through a 4-inch opening, and going larger adds cost without adding real access. Matching the pipe size below 4 inches keeps the opening as wide as the line itself, so a tool is not forced to neck down before it enters the pipe. A cleanout smaller than its pipe creates a choke point that can stop a cable or camera head at the cap, which defeats the whole reason the opening exists.

A cleanout also has to face a useful direction. The code expects the fitting to open so a cable can feed toward the flow of the drain, the direction a clog usually sits. A cleanout plumbed backward, or buried where no one can reach it, does not meet the intent of the code even if the fitting itself is the right size.

A cleanout is only useful if a person can actually get a tool into it, so the code sets minimum clearance in front of the opening. Under UPC Section 707.9, the rule scales with pipe size: about 18 inches of clearance for pipe up to 6 inches, and 36 inches for pipe 8 inches and larger. That space is measured as clear, working room directly in front of the cleanout.

The reason is the tool, not the pipe. To rod a line, a plumber feeds a stiff cable or a jetter hose straight in and pushes. Without room to line up and drive the cable, the opening is there in name only. A cleanout boxed into a tight closet, tucked behind a water heater, or set inches from a wall fails the test even when the fitting itself is correct. Larger pipe carries bigger tools and needs more room, which is why the clearance jumps for 8-inch and larger lines.

The code also wants cleanouts kept accessible over the life of the building. An opening cannot be sealed under tile, paved over, or hidden behind a permanent wall. In Phoenix slab-on-grade homes the lateral cleanout is usually outside near the foundation or out toward the property line rather than in a basement, which keeps it reachable in the open air.

Every required location maps to a real failure point. The junction, the long run, the sharp turn, and the base of a stack are the spots where waste slows down, drops out of the flow, and builds into a clog. Putting an opening at each of those points means a plumber can attack a blockage from the side closest to it instead of fighting the whole line.

Access drives the cost and the mess of every sewer job. With a correct cleanout, a plumber can snake, hydro jet, or camera the line straight from the cap. For the high-pressure side of that work, see our page on what hydro jetting is. Without a cleanout, the alternatives are pulling a toilet, going down a roof vent, or cutting into the pipe, each of which adds time and labor. A camera run also needs that straight shot to find cracks, root intrusion, sags, or buildup.

There is a maintenance payoff too. Blockages are the single largest known cause of sewer overflows, and grease alone accounts for 47 percent of reported sewer blockages, per the EPA Report to Congress on overflows. Code-placed cleanouts let a plumber clear and inspect a line before a slow drain becomes a backup. If you are trying to figure out whether a slow drain is a local problem or a line-wide one, our guide on telling a main line clog from a branch clog walks through the signs.

The takeaways are simple. Your sewer line should have a cleanout where it meets the building sewer, more cleanouts every 100 feet of run, one at any combined turn past 135 degrees, and one at the bottom of each vertical stack. Each one should be the same size as its pipe up to a 4-inch cap, and each one needs open room in front of it, roughly 18 inches for the residential-size pipe most homes use.

The 2024 UPC describes the building drain and sewer system as one that must be "maintained in a sanitary and safe operating condition," and accessible cleanouts are how a plumber keeps it that way. If a new line is being run, an addition is going in, or an older home has cleanouts that are missing, buried, or too small, those are exactly the points an inspector checks and the points a homeowner pays for later if they are skipped. A licensed plumber can confirm your line meets the local amendment and place any cleanout the code requires.