Under the UPC, a long horizontal drainage run needs a cleanout every so many feet of developed length. What is the maximum spacing?
Not quite. The answer is C: 100 feet
The UPC wants a cleanout at the upper end of each horizontal drain and then one for every 100 feet of developed length (or fraction of it), plus an extra cleanout for each aggregate change of direction greater than 135 degrees. Washington's amendments restate the same 100-foot rule. Fifty feet is the figure candidates pick up from other codes, which is the usual wrong answer here.
Reference: WAC 2021 51-56-0700, §707.4 (Cleanout location and spacing)
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