Whenever anyone flushes my second floor bathroom toilet, I have gurgling in the bathtub in the same bathroom, and also have that same gurgling in the kitchen sink (1st floor). I am on a septic system. When the septic tank is first pumped, no gurgling until about a week later. I am guessing that it is because of the level of waste in the tank. Is my problem with the vent pipe connect to that upstairs toilet? Toilet always flushes fine, just with that annoying gurgling sound.

The "gurgle" indicates a vent problem. Let me explain about vents. When you flush a toilet or drain a fixture a suction is created by the water rushing down the pipe. This suction is relieved by a open pipe that runs to the outside called a vent. When a vent's stopped up the suction has to relieve itself somewhere, in this case your tub and kitchen sink. The noise you hear is the air being pulled through the trap by suction. Go up on the roof and shine a light down the lavatory vent. I've seen birds nests, dead birds and critters caught down there and if you can't see anything you're going have to snake out the lavatory vent. Let out enough cable to get to the base and then put out enough to get to the main house sewer. Good luck, Tom

I have done that already, with my 25' auger. Looks like I might have to call a plumber for this one. Thanks for the tip.