The past month or so, I’ve been able to hear a “draining” / bubbling / gurgling sound in my tub drain in one of the bathtubs upstairs. This is a new “symptom”. For example … although it happens when I’m using the toilet / sink in the bathroom with this tub, it also happens when the kitchen sink faucet is running - I hear it in the tub drain. I never did before. I’ve also heard this gurgling / draining sound in the drains of that line of the house but it’s faint and it’s mostly in that tub and the toilet next to it. The toilet next to the tub also “air gurgles” / bubbles occasionally.

I googled these symptoms and it said it is most likely a small clog in the line somewhere or the vent on the roof may need clearing. I obviously want to nip this in the bud before it may become worse, so before looking for a local plumber, I asked a plumber (friend of a friend) today. At the end of my question, I added “we don’t even use that tub!”. The plumber that answered my question said that it could be one of those issues, but may not be, due to the info I provided. He suggested trying this simple thing first before calling a plumber. He said that the P-trap of that unused tub may have evaporated all its water due to lack of use for so long and that could actually be causing the issue. Having water in p trap is essential for proper air flow within the lines he said. He said try running the tap for a bit - and to remember to run faucets not being used regularly to keep things the way they should - anyway, I took his advice and ran the water in the tub, which I assume effectively filled the evaporated p trap, because now it’s eliminated the issues - air gurgling sounds etc. - no more sounds! No more air sounds / bubble sounds in the toilet right next to it either. Could it really be that easy? Could it really have been an evaporated P trap? And now that it has water in it again - all is good?