A sewer smell can be an unpleasant experience and can usually be solved by a process of elimination. Here are some tips you can do to try and resolve the nasty odor.
Drains are designed to hold water in what is called a P-trap, the water acts as a barrier to keep sewer gas from permeating the home. Start by running water down the drains and flushing toilets especially the ones that do not get used often to restore the water in the p-trap.
Check your clean outs to make sure the plugs are installed and secured.
Another culprit could be a bad wax ring seal between the toilet flange and the base of the toilet.
This wax ring can occasionally leak, sometimes from a rocking toilet that has broken the seal causing sewer gas to find its way out from under the toilet. If that’s the case, you’ll have to remove the toilet and replace the wax ring. If the toilet rocks, use shims between the stool and the floor and caulk the joint. This will ensure that a rocking toilet doesn’t ruin the new wax ring.
A more serious problem would be a broken or cracked sewer line or even a loose connection joint in the vent in the ceiling or wall. If you’ve addressed the three easier possibilities, contact a plumber who specializes in hunting down leaks .