Two years ago we had a septic system installed. (You do not want the details of what existed before.) Since that time we have had occasional sewage odors outdoors that we believe is coming from the vent.

Flash forward two years.

I had the bathroom remodeled. During the remodel I requested that the medicine cabinet be recessed. This necessitated the installation of a 'U' in the pipe venting to the outside.

Since then, about 80% of the time following a shower there is that same odor in the bathroom. I have traced it to the toilet base. I went under the house but could find no evidence of leaking.

Is it possible to air is escaping through a slight break in the toilet seal?

Could the vent need to be replaced?

Thank you for your help!

The wax ring under the toilet can leak air and sewer gas even though it doesn't leak water. Replace it. Your vent should not need replacing or service at this time.

Thank you ballengerb1. Will do.

Do you think our vent may also have a clog in it or be to narrow in diameter?

I was reading that the vent pipe should be 4" in diameter and my husband says ours may be only an inch and a half.

Again, thanks very much.

Your vent should be as big as your largest drain pipe, toilets are usually 4" but can be 3".. It does sound like your vent is under sized but bad vents cause toilets and drains to bubble and girgle, not smell bad. That smell is sewer gas likely from a bad wax ring. Vent stacks get leaves and twigs as well as birds and squirrels so they can plug up even in a new house. Replace the ring, its cheap and fairly easy. If the smell is still there then rod from the roof. Use enough rod to reach roof top to basement floor plus 15 ' more with a 1/2" rod as the absolute smallest rod.