If you’ve noticed unpleasant odors wafting up from your drains recently, you may have a growing yet unseen problem on your hands. Often, offensive drain odors become noticeable when decomposing material or a substantial amount of bacteria builds up inside the pipe. As that mass of solid waste or slimy residue grows — which it’s doing by the day — eventually, it’ll form a drain clog.

So what might be causing the nasty odor that’s floating out of your drains? Let’s take a look at the five most common culprits.  

1. Dry P-Trap

Solid material and slimy, bacteria-laden residue are common culprits behind smelly drains. However, another culprit, a dry p-trap, may be causing the stench if you haven’t used a particular drain in some time.

The p-trap in your drain is located just beneath the opening to the drain where the attached pipe forms a u-shape. That section of the pipe is designed to hold a small amount of water inside, which prevents sewer odors from wafting up through the drain.

But when you don’t use a particular drain for a while — say, in a guest bathroom you rarely use — the water inside that portion of the pipe can evaporate. When it does, off-putting sewer gasses can begin traveling up through the pipe and wafting into the room where the drain is located.

Fortunately, this problem is super easy to fix. Simply run the tap briefly to allow water into the drain, so it can refill the p-trap. If pouring water into the drain does nothing to quell the stench, chances are something inside the pipe is causing the odor. Or, your sewer line might be developing a blockage.

2. Trapped Food

If you’re dealing with a malodorous kitchen sink drain, chances are some type of solid food is causing the stench. Often, when people rinse off dishes, peel veggies over the sink, or allow grease to flow into the drain, those materials become stuck inside the pipe. Over time, they start to break down, just as they would in the trash or compost. And as they begin to rot, they also begin to stink.

Avoiding this problem is simple: Place a drain trap in the opening of the drain to catch any solid food particles that might otherwise flow into the pipe. In addition to implementing a drain trap, be sure you’re disposing of oil and grease in the trash, not in the sink.

Nothing belongs down your kitchen sink drain but liquid (not oily liquid), soap, and cleaning products. Even if you have a garbage disposal, it’s not designed to handle oily, fatty substances, and there are several foods it won’t handle well either. If you’re unsure of what's safe to put down your unit, you’ll definitely want to read up on the items that don't belong in your disposal

To remedy a stinky kitchen drain, you can try pouring baking soda, hot water, or vinegar down it, but those things usually don’t get the job done. For best results — and to prevent a more severe, future drain blockage — schedule a kitchen drain cleaning appointment with a pro. That’s a surefire way to both eliminate the odor and ensure your kitchen drain does develop a serious clog.

3. Biofilm

Remember when we mentioned bacteria-laden residue? That stuff is called biofilm, and it’s the slimy, nasty coating that’s currently lining the interior of your pipes. If you’re dealing with a smelly bathroom sink drain, shower drain, or bathtub drain, an excessive amount of biofilm is likely the culprit.

When hair, body care products, body oil, and who knows what else flows down the drains in your bathroom, some of it can get stuck inside the pipe. Since the interior of your drain pipes isn’t exactly pristine, bacteria begin growing on those substances. Over time, as that bacteria proliferates, it begins producing hydrogen sulfide gas, which smells terrible.

Luckily, keeping gunk out of your bathroom drains is pretty simple, too. All you’ll need to do is install drain traps that catch hair and any other materials that would normally flow down the drain. To fix a smelly bathroom drain, it's best to hire a professional drain cleaner. While you can try pouring boiling water, baking soda, vinegar, or even enzymatic cleaner down the drain, again, these tactics are unreliable, and often fail to provide a long-term solution.

A professional drain cleaner can perform a quick drain camera inspection to assess the interior of the pipes and determine if a clog is present. After the inspection, he’ll thoroughly flush the drain using a technique called water jetting, which effectively eliminates every bit of odor-causing residue.

4. Clogged Vent Pipes

Did you know all of the drains in your house are connected to vent pipes that exit through your roof? Those vents are responsible for regulating the air pressure within your plumbing system and preventing a vacuum that would result in slow or incomplete drainage. They’re also partially responsible for controlling unpleasant drain odors.  

Although you’ll never actively use these vent pipes or put anything inside of them, they can become clogged. But rather than getting clogged with waste like your drain pipes, these outdoor vents typically become blocked by debris, such as leaves, pine needles, branches, and even birds nests. During winter, ice can also block your plumbing vents. Some homes do not have an adequate number of vents, which can also cause odor problems.

When a vent is clogged, gasses from within your pipes cannot exit the system through the roof, and because they have nowhere else to escape, they’ll waft up through your drains. If your house doesn’t have the appropriate number of plumbing vents, liquid entering your drains can flush water out of the p-traps, which will allow odors to waft back up through the drain line. 

If you think vents might the culprit behind your smelly drains, you’ll need to contact a plumber to verify whether that’s true. Professional drain cleaning won’t solve this issue as the service is only designed to clean the interior of your liquid-handling pipes, not your vent pipes.

5. Main Sewer Line Problems

If foul-smelling liquid is backing up through your drain pipes, you may have a serious problem on your hands. In some cases, a clogged or excessively full septic tank can cause malodorous liquid or sludge to travel up through your drains. An outdated or damaged septic pump can also contribute to the issue. In other cases, a damaged main sewer line ends up being the culprit behind the stench.  

If you plunge your drains and the liquid still backs up when you run faucets or flush your toilet, call a drain cleaning professional to schedule a camera drain inspection as soon as you can. If the issue is clog related, main line sewer cleaning can typically solve it, but if you’re dealing with a full septic tank or a damaged main line, you’ll need to call a plumber.

Check out 5 Common Signs of a Main Sewer Line Clog for tips on detecting issues with your home’s most important drain line.

Hire Drain Cleaning Services in the Twin Cities Today

If your household drains smell terrible, it’s time to schedule a professional drain cleaning appointment with Drain Blaster Bill. We specialize in commercial and residential drain cleaning, as well as drain camera inspections for properties throughout the Twin Cities metro. From toilet and floor drain cleaning to shower drain and main line sewer cleaning, whatever type of drain you need cleaned, we do them all. If you need same-day service, we do that too!

To get started or learn more about how we can help you, call our Stillwater, MN office today at 763-913-8719, request a free estimate, or contact us online, and we’ll be in touch!