There are many unpleasant things to deal with when it comes to plumbing, but persistent sewer and septic system odors have to be one of the worst. One of the most common plumbing complaints heard by plumbers is that of odors in the bathroom. In some cases the odor will be slight, in some cases it will be strong. In some cases the odor will remain constant, while in other cases it will come and go. Either way, however, it is important to deal with the issue and banish those odors.
The first thought of many homeowners is to mask the odor with a cleaner or a deodorizer, but this will not usually stop the problem from coming back. Homeowners with septic systems should be especially careful about putting chemicals down the drain, since bleach and other types of cleaners and deodorizers can disrupt the normal operation of the septic system and make the problem worse.
If you could look inside the walls of your home you would see a “T” shaped section where the pipe goes into the septic and sewer system and up to external vent. The purpose of this trap is to prevent gas and odor from the septic or sewer system from going back into the bathroom. Every time the shower, sink or tub is used some water will collect in the trap which blocks gases and odors. In some cases this water will evaporate and allow gases and odors to back up into the bathroom.
Since the problem is lack of water the solution is very simple, and that is to simply add water by pouring it down the drain. If the trap is kept full of water the problems with odors should not come back. If the problem was a lack of water then the odor should dissipate quickly once water has been added to the trap.
If water doesn’t fix your sewer problem
There are other causes of odor besides lack of water, and if adding water does not fix the problem the issue may be a buildup of hair, slime, mold or other objectionable materials in the tailpiece. The tailpiece is the part of the pipe that comes out the bottom of the sink. In addition, the pop-up stopper in the tub can also build up with gook and cause an odor problem. A small flashlight can be used to determine if this buildup is a problem. If this is the issue it can be resolved with a good cleaner, but it is important to choose a cleaner that is certified safe for septic systems, here is one of the best companies out there: https://www.the-driveway-company.com/resin/