One of my tenants phoned me this afternoon and stated that there was a clog in the kitchen. My fiancee went over to investigate. He replaced the J trap and got a high pressure tip that goes on the hose. He said that when he did that, the water shot out of the vent on the roof. This house is on a septic and the kitchen is the last in line to go to the tank. Is this just a serious clog, or something worse? There was work being done on the neighbors yard and they used my yard to bring dirt in with a bobcat. I told them specifically that there was a septic tank in the front yard and to avoid that area. Any advice is appreciated. Thanks!