Three Possible Causes For The Sewage Smell In Your Bathroom
Bad smells can come from all sorts of places in a bathroom, but the smell of sewage could indicate a plumbing problem. This odor is most often a result of sewer gases coming back up into your bathroom, such as through your drains, your drain vents, or your toilet's base.
Dry or Clogged P-Trap
With sinks or drains that aren't used much, one common cause of a foul sewage-like odor is that the water sitting in the P-trap has dried up, letting in the smell of sewage.
A P-trap functions by letting water sit at the bottom of the drain at all times, and this water blocks odors and gases from coming back up your pipes. If you don't use a drain often, this water could dry up and let these gases in. Run some water down each drain and see if the smell goes away.
If it doesn't, but the smell seems to definitely be coming from one of your drains, there could be a buildup of gunk in the P-trap. While sometimes this can be fixed by running a handheld snake down the drain, in more serious cases, the P-trap itself may need to be removed and cleaned out. If you aren't having any luck, call a plumber to help locate the source of the smell and clean or replace any parts that may need it.
Clogged Drain Vent
Each set of drains has a vent that helps regulate air pressure inside your pipes, and these vents help keep your drains flowing smoothly. If these vents are clogged, water and waste may flow more slowly even if there are no physical obstacles. What's more, if gases can't exit your home via the vents as they normally do, they may come up through your drains instead.
Vents can be clogged in several different ways. Commonly, debris like leaves and twigs can build up inside the vent and clog it up, but some animals, like birds, can make nests or get stuck inside these vents. If an animal does get stuck, you may not be smelling sewage, but the decaying of the animal's body.
Many vents lead out to the roof of your home, so they can be dangerous to try to fix yourself. Call a plumber to have your vents inspected and cleaned if necessary.
Loose Toilet Seal
Your toilet has a watertight seal keeping it fastened to the ground and to the drain pipe, and if this seal is broken or starts to loosen, gases and odors can start to leak out. Additionally, this also means that wastewater can start to pool on the floor under your toilet, which can start to smell very bad very quickly.
If the smell is persistent and strong, a broken seal may be your issue. If this is the case, the seal will need to be replaced by a professional. The good news is that unless your toilet itself is damaged, it won't need replacing.