7 Common Causes of a Septic Smell in Houses and How to Fix It

You probably never really want to think about your septic tank, but when your home starts to smell less-than-fresh, that tank can be the source of the problem. A regularly serviced septic tank system can last for years, but a septic smell in your house could be a sign of trouble.

Need help troubleshooting a septic smell in your house? Explore seven of the most common causes below and what you can do to fix the stink (and prevent more bad smells).

1. Clogged Drains

If your drains are clogged, they can dry out. And while a dry drain doesn’t sound bad, it can cause problems—like odor! 

When a clog forms, it dries out the pipe, and that means there’s no ventilation, which is essential to combatting odor. Dry drains can’t filter the gases building in the tank. Instead, the gas can seep into the home, causing a bad smell. If you think a clogged drain (or drains) could be part of the problem, contact a plumber near you to take a look.

2. Ice Buildup

In particularly cold weather, ice can build up on the vents of your plumbing pipes. A little ice is no biggie, but too much means air can’t move through the vent, and the gases from your tank will be redirected into your home. Not very nice.

This problem you can handle by yourself if you are able to remove the ice from the vent easily without causing damage. If you’re worried the situation has gone too far, then it’s time to bring in a professional.

3. Blocked Vents

While ice buildup can cause issues, it isn’t just inclement weather that can lead to blocked vents and the bad smells that follow. Your landscaping, if not maintained, can also block those vents. Make sure to regularly trim any bushes that could block the vent, and keep your lawn trimmed, too.

4. Broken Pump

One of the key components of a septic tank system is the pump. The septic pump helps move wastewater in and out of the machine. If your septic tank pump is out of date, it may not be able to meet the capacity demands of your household. 

Contact a plumber in your area to assess the situation if you suspect that a broken pump is to blame for the septic gas smell in your house.

5. Full Tank

While septic tanks naturally treat waste, they can’t keep up with how regularly waste is deposited into the tank. That means you need to have your septic tank regularly emptied. If you don’t, it can back up, leading to bad smells and a potential sewage spill in your home. 

Make sure you are well-educated about the safety issues every septic tank owner should know and keep up with necessary maintenance. You should have your septic tank inspected every one to three years, and the Environmental Protection Agency (EPA) suggests that you have your septic tank emptied (a.k.a. pumped) every three to five years. 

The average cost to have your septic tank pumped or cleaned is $410. Most people spend between $290 and $540. Very large tanks can cost $1,000 or more.

6. Loose or Missing Sewer Trap Plug

Sewer trap plugs (unsurprisingly) plug the sewer access point and prevent sewer gases from leaking out. Because the sewer access point is often found in a basement, garage, or crawlspace, a loose or missing plug means that all those stinky gases are seeping into your home. Luckily, sewer trap plugs are only $10 to $20 at a local hardware store and are easy to replace. 

7. Dried-Out Toilet Wax Seal

At the base of your toilet is a wax seal, or wax ring, that prevents leaks from the bottom of the toilet and stops excessive septic smells from permeating your bathroom. If your seal is dried out, it won’t be able to do its job. If the septic smell is particularly bad in one bathroom, a failing wax seal is a very likely cause of your smelly situation. 

How to Fix and Prevent Septic Tank Smells in Your House

You don’t have to live with a septic smell in the house. There are a few common fixes to consider, like cleaning the drains or scheduling a septic tank pumping. From there, keep up with regular maintenance and be careful with what you pour down the drains to prevent septic smells in the future.

Unclog the Drains

If you suspect the septic smell in your house is from the drains, unclog them with a plunger, snake, or homemade cleaner made with equal parts baking soda and vinegar. But if unclogging the drains doesn’t help, call a septic repair company or plumber to find the source of the smell.

Flush and Pour Carefully

A septic smell in the house can come from clogs in the drains or deeper in the pipes, and septic tanks can be particularly vulnerable to clogs from items like wet wipes or cooking oils. To prevent clogs and septic system damage that can lead to septic odors, make sure to only flush human waste and toilet paper. Avoid flushing items like paper towels, menstrual products, or wet wipes.

In the kitchen, keep fats, oils, and grease, or FOG, out of the drains. Instead, pour these items into a sealable container to throw away with your usual trash. Coffee grounds are another culprit, as they cling together and to other debris in the pipes. Make sure to compost or throw out spent coffee grounds to prevent a clog.

Pump the Septic Tank

When you need to get rid of a septic tank odor outside, it’s likely stemming from too much sludge in the septic tank. Solid waste settles at the bottom of the tank, and over time, it builds up. When the sludge takes up more than 1/3 of the tank, it can cause sewer gas and wastewater leaks, and raw sewage can leak into the yard or back up into your drains. 

Every three to five years, be sure to have a local septic tank repair company come to pump the septic tank. They will remove the sludge and properly dispose of it at a wastewater management facility.

Becca Stokes contributed to this piece.