What to do if you have a stinky sewer smell in your home:
(1) Check to make sure there is no sewer water backing up into your house via a drain.
(This will usually happen in the lowest part of your house.)
~ If there is no sewer water causing the smell....
(2) Check all drains (starting with any floor drains in your basement) to make sure you can see water when you shine a flash light down the drain hole. All drains in your home will have a trap that holds some water just a little ways below the drain. That water creates a barrier to prevent super stinky sewer gas from drifting up the pipes from the sewer, and into your house. See picture below.
When a drain is not used often, the water in the trap can dry up, leaving an open passage for sewer gas to enter your house. Pouring some water down the drain should re-create the water barrier. Open a few windows and the smell should be gone in a few minutes.
A Few "If"s...
because life is hardly ever that easy!
*If you pour water down the drain and it only temporarily solves the smelly situation, (meaning the smell goes away, a short time later the smell returns, and you can no longer see the water that you previously poured into the drain in the trap) your pipe could be broken. Then you need to call your plumber.
*If when you checked your drains you did find sewer water bubbling up ~ Call your plumber.
*If you can see water when you look into all of your drains, and you checked all of your toilets to make sure they are holding water, crack a window and ~ Call your plumber.