We have a second house that is hardly used and I went to try to tidy it up to move in. I was cleaning the bathtub and noticed water was taking a while to drain. As it was draining I head gurgling noises from the bathroom sink. Then I went to clean the kitchen sink and it too drained very slowly, and I head gurgling from the bathroom, I went in and some dirty *** water had backed up into the sink and bathtub(but the the toilet). Is the the clear sign of a clog? What do I do?