Has anyone seen this plumbing before

Found a plastic line off of a copper drain in the basement. I’ve never seen this before. When toilet flushed a few drops of water came out of the plastic line. Does anyone know what this line is for?

Whatever it is, I would be concerned about cross contamination.

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Likely a trap primer for a floor drain or something else that doesn’t often see regular water. It’s to keep the trap from drying out and sewer gas getting in.

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Did that small pipe terminate into a floor drain?

Whatever it is IMO it’s wrong and should be written up as improper installation viewed at the drain lines. Although it’s not totally visible, it also looks as though there may be dissimilar metal corrosion at the fitting.

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Usually when I see this it is an improper drain connection for a water softener, condensate pump, or similar. But your post makes it sound like the other end of the tubing was open. Where was the other end of the tubing?


Trap seal primer.
Recommend: Further evaluation for trap seal primer with integral vacuum breaker.
Just my 2 cents.

I would be looking for a pump. I have never seen a trap primer on a toilet for obvious reasons.


copper?..body too short


Good question.

You mean the plastic tubing was open on one end?
If not, where did you see water (or how did you see water)?


The tubing is clear and it does not terminate, it just floats open over the floor. There is a water softener near by, but doesn’t appear to attach to anything.

It would be very helpful to see where that tube terminates, is the toilet correctly vented? possibly there may be a failing septic and that’s an overflow or it’s a cross connection from a water conditioner, ( all the above done incorrectly by a homeowner most likely). Try to send pictures of where the tube terminates or begins.

Where did the water softener discharge go to?

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