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 p-trap for bathtub
Author: waynemorel (Non-US)

Does anyone know how far can a p-trap be installed for a bathtub?
Can I install a p-trap about 4-5ft away from the tub?
Thank you.

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 Re: p-trap for bathtub
Author: Doug E. (CA)

no. not a good idea. why can't you install it right at the tub with the waste and overflow?

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 Re: p-trap for bathtub
Author: sum (FL)

Did you remove a left handed tub and bought a new right handed tub, something like that?

Edited 1 times.

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 Re: p-trap for bathtub
Author: vic (CA)

Yes, with most plumbing codes you can go 5' IF you increase the size of the trap to 2" as well as increase the trap arm piping to 2" then usually you can go as far as 5' for the trap arm length (if you go exactly at and no more than 1/4" per foot fall).


The maximum length of the trap arm (the horizontal distance from the trap weir to the inner edge of where the air from the vent enters that piping) is determined by the size of the trap, the trap-arm pipe size and the degree of fall (grade) of the trap arm pipe.

If you drop the piping at more than 1/4" per every 1 foot (the 1/4" per 1 ft is the "ideal" amount of grade) that shortens the maximum length allowed for the trap arm.

With most plumbing codes a minimum of 1 1/2" trap is required for a bathtub and 3 1/2' is the maximum distance allowed for a trap arm IF you go exactly at 1/4" per foot drop. If you drop more than that the trap arm won't be allowed to be that long.

You could even increase your trap and trap arm to 3" and that would allow you an even longer distance for the trap arm.

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 Re: p-trap for bathtub
Author: hj (AZ)

I will reread the question, but I got the impression he wants to locate the trap 5' from the waste and overflow connection. Relocating the "P" trap away from the tub is NEVER a good idea. The added distance before the trap seal can become fouled and create odors in the room, and snaking the line can become dicey.

Edited 1 times.

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 Re: p-trap for bathtub
Author: waukeshaplumbing (WI)

here in WI i think the trap offset is 15" vert or horiz

some inspectors will let you get away with a running trap if the trap would be in a area prone to freezing....but 5'...nope

there is a special provision for floor drains having running traps and thats mostly for garage floor drains where you put the trap inside the basement....

i wouldnt do what your asking

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 Re: p-trap for bathtub
Author: vic (CA)


Yup, I believe you are correct hj.

Shows for me not to answer first thing in the morning when still half asleep.


Really appreciate the correction.


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