Unwise to connect 11/4" drain to 11/2" trap?

Apr 16, 2007 3 Replies

I put in a new bathroom faucet. The drain has a 11/4" diamter tail. The existing trap is 11/2". I was advised by the local hardware store that to do the job right, everything should be 11/4" and not to use a reducer in order to attach the 11/2" trap to the 11/4" sink drain.



I didn't think of it at the time, but wouldn't a 11/4" drain going into a larger 11/2" provide for efficient draining? Or is keeping everything the same size a good rule of thumb?



The 1 1/2" trap will be just fine.

Depending on the trap material, there is a rubber reducing washer or a plastic one which the hdwr guy should have in stock.

Jim

I think the person at the h/w store is confused. There is no problems going from a 1 1/4 drain into a 1 1/2 trap. For that matter, you could just as easily go from a 1 1/2 drain into a 1 1/4 trap. In the case of a residential sink in a bathroom or kitchen, it really makes no difference at all if the pipes change from 1 1/2 to 1/1/4 here and there and back again.

you may be just fine, but your hardware guy may be right also. i think the same size design would help me now: i don't like my kitchen's

1-1/2" going into an old design 2" S-trap. it seems sluggish and struggles to push the drain water thru even with an auxiliary vent. i was the 1976 "plumber" and should have piped the tail into a 1-1/2" p-trap first. note that s-traps are not the usual recommended plumbing design these days.

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