Unused? Smells Used!

Called out for an inspection today. Customer stated she had a musty odor in a bathroom. Upon walking through the door of the bathroom we were hit with a very pungent odor. To the customers relief we knew right away that it wasn’t a moldy odor but instead a very strong sewage smell. After about 5 minutes and a strong whiff of the shower drain we found the source. We were told that the bathroom was hardly used which is common to hear in a lot of homes. What people don’t realize is that when a pea trap drain is not used in one area for an extended period of time the standing water in that pipe will evaporate, when that happens there is no longer anything blocking sewage odors from coming back through the lines. Lesson here is even if it isn’t used make sure to run water down those lines periodically to prevent odors from crawling out.