I need your help with a wierd plumbing issue. When the shower is running, water runs in more quickly than it goes out. I think there may be a partial clog in the drain pipe caused when I forgot to drain the gray tank on my usual schedule, but now if DW runs water in the sink, the tub drain picks up speed (vortex is noticeably more violent).
Anybody got a sensible explanation and a way to make the drain run fast all the time?