A sewer smell in a bathroom can be both overpowering and dangerous, with the mixture of toxic and nontoxic sewer gases causing headaches, dizziness and other physical symptoms. A common culprit behind the entrance of these gases into the room is often the toilet, but the drains of other bathroom fixtures, as well as the plumbing pipes themselves, are potential suspects.
Wax Seal Failure
The wax seal is a wax ring that you install between the closet flange and the toilet. The flange rests on top of the drainpipe beneath the floor, under the toilet. This seal blocks sewer gases from sneaking in between the toilet and flange when it does its job. When it fails, you will constantly smell the odor of sewer gases and will also notice water leaking from beneath the toilet each time you flush. Replace the wax ring for this repair.
A lack of water inside one of the traps will allow in sewer gas also. One trap is the curved portion of pipe underneath the bathroom sink. Another trap for the bathtub or shower is hidden beneath the floor. These traps always hold an amount of standing water inside them, which blocks sewer gases from entering. This water sometimes lessens or even evaporates over time, such as when a lengthy amount of time passes in which the fixture is left unused. Pour about a quart of water down the drains of these fixtures. The right amount of water will settle into the trap.
Clogged Vent Pipe
A home's drain waste and vent system connects the plumbing pipes of all the fixtures inside the bathroom, including the toilet, sink and tub, into one system of pipes. Vent pipes are one component of this system. These pipes do not transport water, but one duty they do carry out is venting sewer gases out into the outdoor air. If this pipe is clogged, water can be sucked out of a fixture's trap, leaving the trap exposed to sewer gases entering up through that fixture's drain. Normally, use an auger or a water hose to unclog the vent pipe.
A vent pipe can also be clogged, in which case sewer gas will leak out. Once the crack is located, you often cut out the damaged section and install new pipe and fittings. Or the crack may be in a drain pipe, in which case the pipe will leak both water and sewer gas. If your home has a crawlspace underneath it, you can enter it and seek out any damaged drain pipes.