Nothing is as frustrating as having to cope with drain odor either because you are 
unable to trace or have no clue how to eliminate it. Probably you have already tried all drain cleaning methods and applied different brands of disinfectant, but the smell keeps coming back. What causes the incessant smell? There are many causes including the Proliferation of bacteria due to debris in the drain.
Here are a few ways to reverse the situation:
Add Baking Soda and Hot Water
Baking soda has been used for many years to control drain smells. Pour a cup of the product in the drain and let it stand for a few minutes. Add several cups of hot water. Repeat these steps until the smell disappears. You might also have to follow this routine every few weeks.
Use a Strainer
For bad smells coming from the bathroom drain, there is a possibility of hair and other debris embedded inside the pipes. As the hair collects, the stench develops. Use strainers in your tub and shower drains and this problem might be remedied.
Maintain P-Traps
If your plumbing drain was installed in line with Utah code, it should have P-trap. In ideal conditions, this component “traps” the bad gasses. But, the P-trap needs protection and maintenance to work. Never should the trap be devoid of water, unless you are repairing it. In addition, the P-trap should be well ventilated to prevent the retention of sewer gasses in the house.
Drain smell is a plumbing problem you cannot afford to ignore. As an immediate response to the issue, use the baking soda method. Installing strainers and checking out the P-traps can eliminate the smell for good. If this does not work, consider investigating the drain further, and even hire a drain expert for thorough diagnosis and repair.