7.1 Cleanouts: Location, Spacing, Size, and Clearance (UPC 707 as Amended by Washington)
Key Takeaways
A horizontal drain needs a cleanout at its upper terminal, one for each 100 feet of developed length, and one for each aggregate horizontal change of direction exceeding 135 degrees (WA 707.4).
A cleanout may be omitted on a horizontal drain less than 5 feet long unless it serves sinks or urinals (WA 707.4 exception 1).
Washington's 707.9 requires 12 inches of clearance in front of cleanouts on pipe 2 inches or smaller and 18 inches on pipe over 2 inches.
Under Washington's 707.9, an under-floor cleanout may be no more than 20 feet from an access door, trap door, or crawl hole.
UPC Table 707.1 requires a 1-1/2-inch cleanout for 1-1/2 and 2-inch pipe, 2-1/2-inch for 2-1/2 and 3-inch pipe, and 3-1/2-inch for 4-inch and larger pipe.
Why Cleanouts Appear on the Part 2 Drawing
L&I describes the Part 2 exercise as a building drawing showing "the illustrated piping for the vents, waste, and cleanouts." Expect questions on where cleanouts are required, where they may be omitted, and what size they must be. Washington amends two cleanout sections, so know the Washington numbers.
Where Cleanouts Are Required (Washington 707.4)
Each horizontal drainage pipe shall be provided with a cleanout at its upper terminal, and each run of piping that is more than 100 feet in total developed length shall be provided with a cleanout for each 100 feet, or fraction thereof, in length of such piping. An additional cleanout shall be provided in a drainage line for each aggregate horizontal change of direction exceeding 135 degrees.
Exceptions:
- A cleanout may be omitted on a horizontal drain less than 5 feet long, unless the line serves sinks or urinals.
- A cleanout may be omitted on a horizontal drainage pipe installed on a slope of 72 degrees or less from vertical (a one-fifth bend).
- Except for the building drain, its horizontal branches, and urinals, no cleanout is required on piping above the floor level of the lowest floor of the building.
- An approved two-way cleanout fitting may replace an upper-terminal cleanout. It may be installed inside the building wall near the connection between the building drain and the building sewer, or outside the building at the lower end of the building drain and extended to grade.
The unamended 2015 UPC also requires a cleanout above the fixture connection fitting for every urinal. Washington's version of 707.4 does not include that sentence. Urinal drains are still singled out in exceptions 1 and 3.
Counting aggregate change of direction
Add the horizontal turns along a run. Two 90-degree turns = 180°, so one additional cleanout is required. A 45° plus a 90° turn = 135°, which does not exceed 135°, so no additional cleanout is needed for that pair. A third 45° turn (180° total) would require one.
Cleanout Construction and Installation
| Section | Rule |
|---|---|
| 707.1 | Cast-iron pipe cleanouts use a cast-iron or copper-alloy body and an approved plug. Other pipe uses the plugs in Table 707.1, a copper-alloy cap, or an approved ABS, PVC, or stainless plug. Plugs have raised square heads or countersunk slots |
| 707.3 | Cleanouts are watertight and gastight |
| 707.5 | Cleanouts open in the direction of flow or at right angles to it. Except for wye-branch and end-of-line cleanouts, they are installed vertically above the flow line |
| 707.6 | A cleanout extension is drainage piping, and each 90-degree extension comes off a wye-type fitting or equivalent |
| 707.7 | An interceptor's cleanout must be outside the interceptor |
| 707.8 | Cleanouts are above grade and readily accessible, unless under an approved cover plate that still gives the required clearances |
| 707.12 | Countersunk plugs where raised heads would be a hazard |
| 707.13 | A hubless blind plug used as a cleanout must leave the whole coupling and plug accessible |
| 707.14 | Trap arm cleanouts follow 1002.3 (Section 9.2) |
| 710.1 | Cleanouts on drains through a backwater valve are labeled "backwater valve downstream" |
Clearance (Washington 707.9)
| Item | Washington 707.9 | Unamended 2015 UPC |
|---|---|---|
| Front clearance, pipe 2 inches or smaller | 12 inches | 18 inches |
| Front clearance, pipe over 2 inches | 18 inches | 24 inches |
| Under-floor cleanouts | Extend to or above the finished floor, or outside the building, where there is less than 18 inches of vertical clearance or 30 inches of horizontal clearance from the access | Same |
| Maximum distance of an under-floor cleanout from an access door, trap door, or crawl hole | 20 feet | 5 feet |
Cleanout Size (Table 707.1)
| Pipe size | Minimum cleanout size | Threads per inch |
|---|---|---|
| 1-1/2 in | 1-1/2 in | 11-1/2 |
| 2 in | 1-1/2 in | 11-1/2 |
| 2-1/2 in | 2-1/2 in | 8 |
| 3 in | 2-1/2 in | 8 |
| 4 in and larger | 3-1/2 in | 8 |
Section 707.10 requires cleanout fittings to be not less in size than Table 707.1.
Worked Example
A one-story commercial building has a 4-inch building drain running 140 feet from its upper end to where it leaves the building. It makes one 90° and one 45° horizontal turn. A 3-inch branch 4 feet long serves a floor drain, and a 2-inch branch 4 feet long serves a mop sink.
- Upper terminal of the building drain: cleanout required.
- Length: 140 feet is more than 100 feet, so one more cleanout is required within the run. That is 100 feet, then a fraction of the next 100.
- Turns: 90° + 45° = 135°, which does not exceed 135°, so no additional cleanout is needed.
- 3-inch floor drain branch, 4 feet: less than 5 feet and not serving sinks or urinals, so exception 1 allows omitting the cleanout.
- 2-inch mop sink branch, 4 feet: a mop basin is a sink. Exception 1 does not apply, so it needs a cleanout at its upper end.
- Sizes: 3-1/2-inch cleanouts on the 4-inch drain, and a 1-1/2-inch cleanout on the 2-inch branch.
- Clearance: 18 inches in front of the 4-inch drain cleanouts and 12 inches in front of the 2-inch cleanout (Washington 707.9).
Under Washington's amendment to UPC 707.9, what clear space is required in front of a cleanout on a 3-inch drain?
30 inches
12 inches
18 inches
24 inches
A horizontal drain makes two 90-degree horizontal turns between its upper-terminal cleanout and the stack. How many additional cleanouts does Washington's 707.4 require for the turns?
One
Two
Three
None
What is the minimum cleanout size for a 4-inch drainage pipe under UPC Table 707.1?
4 inches
2-1/2 inches
3 inches
3-1/2 inches
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