I have a strange plumbing problem, was searching the internet for a clue and found this forum. It looked like a nice bunch of folks so I registered.
Here's my problem. My house is about 25 years old. The sink is a porcelain, double basket, with a waste disposal under the left side, and a dishwasher connection.
Earlier today my wife was washing dishes; she had the stopper in the right side, full of water, and the faucet running into the left side for rinsing. After she let the water out of the right side she walked out onto the concrete patio and there was a water puddle on the concrete. The outside wall is stucco, and right down near the concrete there is a little hole where I can just barely see the down pipe from the sink drain.
After coming home from work I was able to recreate the problem by filling the right side with water, run the faucet into the left side, then release the right side into the drain. Then, through the little outside hole, I could see water dripping down from inside the wall. It's not coming from the pipe, at least not in the area of the hole.
I found this web site that talks about an Air Vent on top of the down pipe:
Scroll about half way down the page to see what I'm talking about.
What I'm wondering is, do you think I might have one of these in the wall, and the water is backing up into the down pipe and coming up out of the Air Vent? I can see this happening if the drain is partially clogged.
I checked all of the plumbing under the sink, it's all dry. I can't think of anything else.
Oh, and by the way, all of the pipes (except for the down pipe from the right sink basket) are PVC.
Anybody have an idea what's going on? I can supply pictures, if that would help, just let me know.