: Can I get some opinions on installing clean-out fittings on the 2nd floor of a single family dwelling. The code requires a c/o at the end of each horizontal branch or in the vertical pipe as long as it is above the flood level rim. Who is ever going to use this c/o on the 2nd floor anyway. Does this make any sense to you?in my area–toilets, p-traps under lavatories,tub drains and etc count as clean outs on second floor. on ground level trunk lines are run through to exterior wall with clean outs.you may have to ask your plumbing inspector what his interpretation of the code is.