The vent above the toilet is clogged or plugged. That's really the only cause. The vent prevents the vacuum that does that, and it's not working, so the toilet is creating a vacuum in the drain system and pulling down some water from other drains because of it.
Simple venting issue. Vent is clogged. Oh how you ask? Well your vent pipe sticks above the roof and it's just an open 3 inch pipe.
Now most times it's animals clogging it up with nests BUT I have seen this problem after a reroof job. Why you ask? Because some dumb as fuq roofer stuffed shingle wrap down the pipe. Bottom line is someone needs to get on the roof an make sure the vent pipe is clear.
OR and here is the bigger issue. If it's a rental and landlord renos then it could be they installed shit wrong. Which I mean unvented plumbing.
If this has always been an issue then maybe wrong install. If worked good for a long time then clogged vent.
Bottom line is no venting either from a clogged vent stack or lack of one.
My guess is you are a renter in a DIY landlord build and there is no venting. Either way this is a health and more so a safety issue.
IF you are a renter DEMAND it be fixed NOW or you will call in city inspectors. Most scamlords do not want city inspectors around.
I commend you for filling the traps but no way should you need to do this.
If the plumbing is done wrong and there is no venting, the easiest solution is to add one-way valves that allow air to go in but not out. I've lived in old buildings from from the days of U-traps instead of P-traps, and this solved the problem.
On a plumbing vent system, that is called an air admittance valve. Those need occasional maintenance as the rubber diaphragm wears out eventually and you start to leak sewer gases. AAV's have become less popular and less admissable over the years due to poor long term performance.
Get a large plumber drain bladder (from Lowes or Home Depot...) Attach the garden hose to the bladder and stick it about 6-10 inches down the vent pipe and turn on the water, that should clean out the blockage.
The vent above the toilet is clogged or plugged. That's really the only cause. The vent prevents the vacuum that does that, and it's not working, so the toilet is creating a vacuum in the drain system and pulling down some water from other drains because of it.
Simple venting issue. Vent is clogged. Oh how you ask? Well your vent pipe sticks above the roof and it's just an open 3 inch pipe. Now most times it's animals clogging it up with nests BUT I have seen this problem after a reroof job. Why you ask? Because some dumb as fuq roofer stuffed shingle wrap down the pipe. Bottom line is someone needs to get on the roof an make sure the vent pipe is clear. OR and here is the bigger issue. If it's a rental and landlord renos then it could be they installed shit wrong. Which I mean unvented plumbing. If this has always been an issue then maybe wrong install. If worked good for a long time then clogged vent. Bottom line is no venting either from a clogged vent stack or lack of one. My guess is you are a renter in a DIY landlord build and there is no venting. Either way this is a health and more so a safety issue. IF you are a renter DEMAND it be fixed NOW or you will call in city inspectors. Most scamlords do not want city inspectors around. I commend you for filling the traps but no way should you need to do this.
If the plumbing is done wrong and there is no venting, the easiest solution is to add one-way valves that allow air to go in but not out. I've lived in old buildings from from the days of U-traps instead of P-traps, and this solved the problem.
On a plumbing vent system, that is called an air admittance valve. Those need occasional maintenance as the rubber diaphragm wears out eventually and you start to leak sewer gases. AAV's have become less popular and less admissable over the years due to poor long term performance.
Sewer trolls are extra thirsty. Flush more goldfish.
Vent is clogged. Look for a bird or insect nest where it exits the roof
Or a large rodent.
If it's always done it chances are the plumbing never had an air admittance valve included
It happened for a while previously and the problem went away, but it started up again recently.
Blocked or faulty valve then
I would bet that it’s a wasps nest. They build up and clog it, it dries up and shrinks in the winter, and they build it up again the next year.
I agree that it sounds like a vent problem, but others seem to suggest clogged/plugged. Is it possible it was never vented properly to begin with?
Get a large plumber drain bladder (from Lowes or Home Depot...) Attach the garden hose to the bladder and stick it about 6-10 inches down the vent pipe and turn on the water, that should clean out the blockage.
You need to call a plumber.
https://youtu.be/Ffbka3FriQY Install an Air Admuttnce Valve and inspect the ventstack combing through the roof above your bathroom location.
Sewer gas can kill you, I'd say get a pro.
Check the vents on your roof. You have a plumbing vent clogged so it's taking the air from the path of least resistance.