Help - this is a follow up post from my original post back in October. For several months now, whenever we wash clothes, our toilet has been loudly gurgling and some water drains out of the bowl with each gurgle - almost to the point that it's completely empty. Sometimes, but not every time, water will also simultaneously back up into our tub. We have a "sump pump ejector" hooked up to our washing machine in the basement, for the sole purpose of taking the water that drains from the washing machine and getting it out of the house. It is not there because our basement gets water during heavy rains or anything of the sort. Anyway, we have snaked everything possible, including the vent pipe that is vented to the roof. We have gone out in the front yard and removed the cap on the water line and watched the water flow during a full cycle of the washing machine, and everything seemed to be exiting properly. We have even tried flushing Roebic root killer down the toilet several times in the past 2-3 months. Nothing is helping. Everyone we've talked to and everything I can find on this subject indicates a clogges vent pipe -- but we have snaked it three times, each time with no resistance or indication of any clogs -- and still this issue persists. Thoughts, opinions??? All are welcome!!! We have called a few different plumbers to see if someone will come out and take a look, and each time we describe the situation over the phone, they act like they have no idea what we're talking about and they decline to even come over and look. Also -- anyone ever heard of a "check valve" needing to be installed on one of these things? Someone had suggested it but they didn't go into much detail and we're not real sure about it. Thanks for taking the time to read this.