Seal a backup drain from sewer gas?

Question

I want to install a backup drain for a bathroom where there might be overflow onto the floor. The problem is how to seal that drain against sewer gas. The usual P-trap cannot be used because the drain will ordinarily never be used. It is just there in case of an unusual overflow condition, like someone flooding a sink for example.
How can I seal the drain from sewer gas?

Ecnerwal · Answer

The ordinary P trap is required to be used, as I'm quite sure that you live in an area covered by ordinary plumbing codes.
A Trap Filler AKA Trap Primer and/or a floor drain seal may also be required to protect the trap seal.
https://codes.iccsafe.org/content/IPC2018/chapter-10-traps,-interceptors-and-separators#IPC2018_Ch10_Sec1002.4
IPC 1002.4 Other codes will be similar.

redlude97 · Answer

Normal p trap filled with mineral oil

Jasen · Answer

Plumb one of the washing fixtures into the floor drain. (like a shower or a hand basin)
Then it will see periodic use, and not dry out.

Seal a backup drain from sewer gas?

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