I have a leak coming from the upstair bathroom down to my laundry room. I cut a hole in the ceiling in the laundry room to try to see were the leak was coming from but it is blocked by wood right above the drywall. Next I pulled the toilet off thinking it was the wax seal. I poured a bucket of water in the center of the hole were the toilet drains and the leak started again downstairs. It does seem to leak when the shower is on, mybe it is because not as much pressure all at once. How can I fix the leak without having to pull the floor up or tearing my ceiling down? All of the piping seems to be black plastic type. Any info greatly appreciated. I looked back thru the past post but nothing matched my problem.

I just purchased an older home. Any time the water is running in the kitchen sink or the washing machine is draining you can hear gurgling in the bathtub drain and kitchen drain. I've been told it is a venting problem...I put a bladder in the vent pipe on the roof and tried flushing the vent. I could hear water in the pipes while doing this but not sure if it cleared it...still hear the noise... any and all advice would be appreciated...Thanks...