While running the clothes washer I've noticed that on the rinse cycle the bathtub drain backs up with some not so good smelling water and also seems to drain very slowly. Initially I thought this might be a clogged sewer main, but after inspection I noticed the bathroom drain has standing water inside almost coming into the tub itself. I was able to get access to the plumbing behind and noticed this arrangement. The blue line is the bathtub, red is the washer drain, and green is the bathroom sink. I'm not sure what the other pipe extending upward is marked "?". It really seems that the bathtub drain sits too low to work correctly. Is there anything I can do about this other than raising the entire tub?

Hello all, In order to save some money, I replaced Kohler pressure valve to stop leaky shower myself instead of hiring a plumber. I did it in my other shower without a problem. Now, though, the water turns boiling hot instead of cold when it first starts. In other words, when you turn on the water, normally, it goes from cold to hot. Now, it is going boiling hot to cold. Whereas, it says cold on the metal plate is hot, and hot is cold. Does this make sense? Anyone know what I did wrong and how I can fix this? Thank you!!