Hello, I am installing a new bathroom vanity and sink. My sink has a 1 1/4 drain, however my outlet at the wall is 1 1/2. The configuration I have right now (all slip joint connections) is the 1 1/4 sink drain coming down to a 1 1/4 extension coupling (threaded one end other end is regular pipe). This connects to my 1 1/2 p trap which connects to the 1 1/2 outlet. To reduce at the p trap I used the 1 1/4 to 1 1/2 reducing washer that comes with the p trap. Now for my problem. When I run the sink there are no leaks and everything seems fine. However about 5 minutes later I notice that water seems to be seeping out at the reduction washer and the slip joint connecting the sink to the 1 1/4 extension coupling(which has the wedge shaped washer). The reduction washer is slightly above where the trap water level should be, and the other slip joint is a good 6 inches above that. I am not sure what is causing this back pressure, I would assume that the bigger diameter outlet would theoretically have a lower pressure and would slightly draw the water more that way. Any thoughts?