6.3 Cleanouts and Building Sewers

Purpose and Sizing of Cleanouts

Cleanouts are access points equipped with removable plugs, allowing maintenance equipment (cables, hydro-jetters, cameras) to enter the drainage system to clear blockages. Under IPC Section 708, cleanouts must be designed to open in the direction of waste flow or at a right angle to it, ensuring that sewer rods can be pushed downstream toward the main sewer.

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Required Cleanout Locations (IPC Section 708.1.1)

To ensure complete system maintainability, cleanouts are mandated at specific high-risk points where blockages typically occur:

1. Horizontal Intervals: Cleanouts must be installed at intervals of not more than 100 feet (30.48 m) along horizontal drainage lines.
2. Changes of Direction: A cleanout is required for each change of direction in horizontal drainage piping that exceeds 45 degrees. If multiple changes occur in a short run, they may share a cleanout, provided the total change in direction does not exceed 135 degrees between cleanouts.
3. Base of Stacks: A cleanout must be located at the base of each vertical soil stack, waste stack, and rainwater leader.
4. Junction of Building Drain and Sewer: A cleanout must be installed at the transition from the building drain to the building sewer. This cleanout can be located inside or outside the foundation wall, but must be within 10 feet (3048 mm) of the wall. If an outside cleanout is used, it is typically brought up to grade.

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Cleanout Sizing (IPC Table 708.1.2)

Cleanouts must be sized to accommodate cleaning tools. A cleanout that is too small prevents larger cutter heads from passing through. The minimum size of the cleanout plug is determined by the size of the drainage pipe it serves:

[!IMPORTANT] Exam Tip: Note the 4-inch cap. For 4-inch, 6-inch, 8-inch, or larger pipes, the minimum required cleanout size is 4 inches. You do not need an 8-inch cleanout for an 8-inch sewer line; a 4-inch cleanout is code-compliant and sufficient.

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Cleanout Design, Materials, and Plugs (IPC Section 708.2)

Cleanouts must be constructed of approved materials and equipped with compatible plugs:

• Plug Materials: Plugs must be made of brass or plastic. If cast iron piping is used, the cleanout ferrule can be cast iron, but the plug must be brass or plastic to prevent galvanic corrosion and seize-up.
• Countersunk Plugs: In areas subject to pedestrian traffic or cleaning equipment (e.g., hallways, lobbies, kitchens), cleanout plugs must be of the countersunk type (flush with the floor or wall) to prevent tripping hazards.
• Test Tees: Cleanouts are often installed in the form of a test tee. A test tee allows the inspector to insert an inflatable test ball to seal the drainage line, facilitating the required gravity water test.

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Clearance and Accessibility (IPC Section 708.1.5)

Cleanouts must be accessible and have enough clear space in front of them to allow sewer cables to be fed into the pipe. The code mandates the following clearances:

• Pipes 4 inches and smaller: A minimum of 18 inches (457 mm) of clear space must be provided in front of the cleanout.
• Pipes larger than 4 inches: A minimum of 36 inches (914 mm) of clear space must be provided in front of the cleanout.

Access Cover Plates:

• Cleanouts located in walls must extend to the surface of the wall or be accessible through an access panel.
• Cleanouts located under concrete floor slabs must be extended to the floor level or terminate in a flush floor box with a cover plate so they can be accessed without breaking the slab.

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Drainage System Testing and Inspections (IPC Section 312.2)

Cleanouts play a critical role in system testing. The plumbing code requires all sanitary drainage piping to be tested before approval:

• Water Test: The drainage system is filled with water to a point at least 10 feet (3048 mm) above the highest joint being tested. The pressure must hold for at least 15 minutes without any leaks.
• Air Test: If a water test is not practical, an air test can be performed at a uniform pressure of 5 psi (34.5 kPa) for at least 15 minutes.

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Building Sewer Installation and Water Line Separation (IPC Section 710)

One of the most critical safety issues in plumbing inspection is protecting the potable water service from contamination by a leaking sewer line. IPC Section 608.12 and Section 710 require that the building sewer and the water service pipe be installed in separate trenches.

However, they may be installed in the same trench if they meet the separation exception:

1. The bottom of the water service pipe at all points must be at least 12 inches (305 mm) above the top of the sewer line.
2. The water service pipe must be benched on undisturbed or compacted earth on one side of the trench.
3. The sewer pipe material must be approved for use inside buildings (e.g., Schedule 40 PVC/ABS or Cast Iron) and must be pressure-tested to ensure it is watertight.