What is this pipe for?

Have seen this before and never been able to figure out what it is. Don’t see it all the time, but occasionally. It is a small plastic, presumably pvc, pipe sticking out of an exterior wall. It is NOt the water heater pan drain, TPR drain, A/C condensate drain. It was located on a dining room wall. Closest plumbing type stuff was probably 20’ away further to the left in the picture.

What the heck is it?

strange pipe.jpg

Is there a fire control sprinkler system installed?

Water conditioner discharge, sump pump discharge, air intake for furnane, high efficency water heater discharge/vent

Would have to say no to all of the guesses so far. Slab foundation, no sump pump, typical for this area gas furnace in attic, typical gas water heater in garage on other side of house.

Keep the info coming!


Considering the location above ground and size of copper fitting (appears to be 3/4"-1" elbow), I’m gonna guess it is the discharge line off the TPR valve of the Water Heater.
Did you see a location for TPR discharge on other side of house for WH. Our code requires it go to the outside.


I went back to your 1st post. I missed the reference to Plastic/PVC. If this is a two story home and laundry room is on the 2nd floor, look for aux. drain pan under the washing machine.

BINGO!!! I think you are right. This home had the laundry room upstairs (realtively rare around here) with a pan under the washer. Thinking back, I believe the other places I have seen this had an upstairs laundry room as well.

Thanks Greg!

Drink a six pack, pee in the drain pan under the washing machine, see if anything comes out the pipe.

See those a lot here where the laundry is on the second floor. Though I occasionally see the laundry on the second floor without an exterior drain for the pan or sometimes even NO pan.

Code & common sense typically require an exterior drain for all laundry rooms located on the second floor.

Nevermind the pipe. What’s that white stuff all over the ground? :roll:


We received the same amount here in Toronto this morning[first time this year] and it was gone by the afternoon.

I think it’s called “White Mold”:mrgreen:

I would have to retire, and lock all the doors. I don’t do cold. . .

Mouse access pipe.

Erby - Where in the code does it say you have to have a drain pan on the second floor.? The only place I found this was manufacturer recommendation and not in the code.

Where did you find margarita six packs? :shock:

Here in my area those pipes are, indeed, from the floor drain in the laundry room on the second floor.

Well if “mold is gold,” then “white mold is…” Silver? Platinum? Cocaine? Sugar? :margarit:

Believe it or not we had snow in Texas along with sleet and ice on bridges last week. Went from 80 degrees Wednesday afternoon at 5pm to 30 degrees by about 7pm. Rained, had “thundersleet” and 13 straight hours of news coverage on some of the local channels about the “ARTIC BLAST!” Gotta love Texas weather. Personally, I hope it continues, we need a good wet cold winter to kill bugs and help the drought conditions.

Why would you want to kill some of God’s creatures? You’re messin’ with the food chain. :margarit:

Yup. i want them dead. If the choice is to pay a pest company or have mother nature do the dirty work, I pick her seems more natural. Not to mention, after the 45 or so days over 100 this year, I just like the change.

Ice Cream!