As long as the water is draining smoothly, most people don't give sink and bathtub drains much thought until foul odors begin to emanate from them. If you are having this issue, it's vital that you determine the source of the odor. Some issues you can fix yourself, while others could be forewarning of a much bigger problem. The following guide can help.
Where is the smell coming from?
The first step is to determine which drain is producing the odor. If it's from a single drain, like the kitchen sink or bathtub, then the problem is probably only in that drain. If it's from a group of drains, such as all the drains in the bathroom or on the second floor, then the problem is in the pipe connecting that section of your home to the main sewer line. When all the drains have a foul odor, the issue is likely in the main sewer line.
Can you identify the smell?
Often odors are fairly identifiable. For example, it's common to smell rotting food from kitchen drains. Sour smells are common issues in bathroom drains, as they are formed from a combination of soap residue and rotting hair in the drains. A sewer odor, especially from multiple drains, can indicate a backup in the main sewer line.
Did you try to freshen the drain?
You can take steps to fix the issue if it's only from a drain or two. Begin by pouring boiling water down the drain – this should clear away most odor-causing residue. If you have a garbage disposal, run it while putting water down the drain. Next, pour a a half cup or so of baking soda down the drain and allow it to sit for a little while to absorb odors. Follow this with a cup of lemon juice or vinegar to finish neutralizing odor and freshening the drain.
Is the trap working?
When the issue is sewer odors from one drain and freshening it doesn't help, then there may be a problem with the trap. This is the curved pipe below the sink. A small amount of water is supposed to stay in the trap so that sewer gas can't come back up the pipe. If you don't use a sink often, the water can evaporate and gas can come into the home. Small leaks can also slowly drain traps, which means you will need to replace it.
If you are concerned that the issue is in the main sewer drain or if the above guide didn't solve the problem, call in a plumber to treat your drain odors.