My basement always smells like a sewer.
Whenever I open up the main trap, I feel the
wind blowing and a smell coming out of it.
It seems that this smell is leaking out of
the trap. How can I fix this ?
There should be some water down in the trap which acts as a barrier to escaping gas. Sometimes when it has been dry for a long time the water in the trap will evaporate. Try pouring a few gallons of water down the hole. This should fix the problem until next time it drys out.