Trying to cap a water line that connects to my sewage out line. I purchased a cleanout adapter with cap in 2" and 3" and one is too big and one is too small. I think I need a 2-1/2" connector.

NOWHERE in my local brick-and-mortar stores can I find this size, which leads me to believe...

  1. I am measuring incorrectly, or
  2. The builder used some off-the-wall size and that is why I am having such a pain time to find the correct cap

To use the convertor coupler, is this the right size I'd need? (tried to block out the local box store as I wasn't certain if that was permitted to post)

enter image description here

  • 2
    Have you considered a 2-1/2" to 2" adapter, followed by a 2" cleanout ... ?
    – brhans
    Mar 16, 2022 at 17:52
  • @brhans - i have not. I know very very little about plumbing....how would I do that? Mar 16, 2022 at 18:09
  • need a pic of the line with a tape measure across the end for reference, you may be measuring wrong... Mar 17, 2022 at 4:51

2 Answers 2


If you can't find a 2-1/2" cleanout adapter, but can find a 2", then consider this option instead:

Depending on your local suppliers, you might be able to find a cleanout adapter which will fit directly into the end of the reducer coupling, which then makes the 6" stub of 2" pipe unnecessary.

My (layman's) interpretation of the IPC - 708.7 Minimum Size rule for cleanouts is that Exception 1 probably applies:

stack cleanouts that are not more than one pipe diameter smaller than the drain served, shall be permitted

  • Home depot is closest to me...is this the right size? homedepot.com/p/… Mar 16, 2022 at 18:27
  • No, that's a 1-1/2" x 2" - you need a 2-1/2" x 2" (although that listing is a bit weird and difficult to make sense of). And (lol) now that I'm looking, it seems like that reducer is about as scarce as the 2-1/2" cleanout adapter is ... You might just be better off ordering the 1-1/2" adapter online :P
    – brhans
    Mar 16, 2022 at 18:38
  • haha - it is insanely scarce! I can't find it anywhere! I think i'm just going to purchase the first two images you posted above so I get the right things. I've already got the pvc cement as well as the cleanout adapter with plug. I don't have 6'' to spare, I assume it would work all the same if I cut the 6'' pipe down to about 2'' - 3'' ? Mar 16, 2022 at 18:39
  • You could also go up to 3" for the cleanout. And you can get cleanout adapters that glue straight into a hub, with no intervening pipe needed.
    – Ecnerwal
    Mar 17, 2022 at 14:48

If you have both sizes in hand and neither fits the pipe, then it's not an issue of measuring...

You don't indicate what brick and mortar stores you've looked at. I'm presuming you when to the local big-box retailers. Try an actual plumbing supply house instead. I'm pretty sure they'll have exactly what you're looking for. Bring them a pic of a tape measure across the pipe you're looking to put the fitting on and show it to the guy at the counter. Either he'll point you in the right direction or he'll have it pulled off the shelf in the back room before you put your phone away.

  • Unfortunately for me, even the local plumbing stores only have 2'' or 3'' -> as well as my box hardware stores Mar 16, 2022 at 17:41
  • That seems unusual, @StanleyJones. I'd expect the plumbing store to be able to order what you need. Might take some time with all the supply issues right now, but that's better than not getting it at all.
    – FreeMan
    Mar 16, 2022 at 17:42
  • I live out in the middle of no-where. Maybe the two places I called were just unwilling to really assist, they placed me on hold and came back a few moments later and said they do not have and can not get a 2 1/2'' Mar 16, 2022 at 17:43
  • if I can find the right piece online I'll order it myself, lol Mar 16, 2022 at 17:43
  • 2
    Well yeah, you get that with phone enquiries, if the customer didn't walk in to place the order, how likely are they to come in and and pay, especially if they find it cheaper or faster elsewhere. If you rock on up cash in hand they can probably get a special order in for you.
    – Jasen
    Mar 17, 2022 at 3:35

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