I noticed a few days ago that, whenever my dishwasher is draining, the sink in my kitchen island gurgles (glug, glug, glug). I THINK that the sink connects to the main kitchen sink drain underneath the floor. Any idea what could be causing this? Also, I'm not sure if it's related but I just noticed that my upstairs bathtub is draining really slowly now. But I'm pretty sure it's a separate line until it gets to the Septic connection like everything else.