Looking at a job recently I noticed plumbing I had not seen before. It went like this, Laundry sink faucet, behind the taps a 1/4″ tube runs down off it to a 3/4″ abs pipe that connects to a 2″DWV and disappears into the concrete floor. looks like a trickle line to keep a P-trap full. Anyone know what this is?
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maybe a seldom used sink that the p-trap would run dry and start to smell up the place, my parent house had a floor drain that would dry out and let the septic tank odors back in- took a while to figure out what stunk but once we/they did all it took to fix was a glass of water dumped down the drain once a week or so. Maybe this was just a work-a-round to keep the trap full.
For the floor drain there is an oil plumbers get from the supply house for this purpose. I am sure this is what is needed. The oil doesn't dry out and is safe for the drain. It is specifically for p-traps. Hope this helps. I certainly know what that smell is now because my own p-trap has dried out before.
Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK
There is somethign that I think is called a self-priming trap, but could not find one.
But here is an adaptor that you can use to put a tricle into the trap.
http://www.pppinc.net/ba.htm
It is not uncommon around here to be required to let a small amount of water run down the drains to keep the water pipe from freezing in the winter or a lot more water running to keep drain from freezing, because someone did not get one of them deep enough in the ground. Could that be what the plumbing is?
It's not the best practice to have potable water connected to a drain line without an air gap. Waste water can back up into the potable piping if pressure is lost from a power failure or break.
Does the washer have one of those pans to catch leaks? Maybe this is used to keep that trap full.
Al Mollitor, Sharon MA