After reading this related question and check that the wax seal is ok, I assume I have a problem with the trap, but where's the trap? The outline of the plumbing in my home (a bit simplified) is like this:
- Blue: the main pipe that comes from the bathroom to the city wastewater system through the house basement.
- Yellow: City wastewater (I can't touch it).
- Red: The problem.
- When I bought the house, there was a bad smell in the bathroom. I assumed it was because nobody lived there for months.
- After some weeks, the bad smell didn't dissapeared, so I checked the bathroom (everything right), then I opened a manhole I found in my garden (the red part). I found it dry and had a strong bad smelling.
This get rid of the bad smell for 3 months, but after it eappeared again. Then we cleaned the strap and the bad smell dissapeared again for another 3 months.
Of course, that's not a good solution for 2 reasons:
- We have to clean the trap (at least) 4 times every year.
- Worst: after a couple of month the main pipe is full of water because it doesn't have enough slope. I'm afraid a day it can explode and flood the basement.
So, the question is: how can I fix this? There are no other traps in the house, should I make one? Or there is a simpler way to fix it?