Yes, Mouthwash Can Fix Stinky Drains in a Pinch

Given its germ-fighting properties, mouthwash has some unusual uses beyond just freshening your breath. One popular alternative use for mouthwash is as a drain deodorizer: It's said that pouring mouthwash down a stinky drain is a fast way to solve the problem, leaving your pipes smelling minty fresh. We were curious if this hack really works, so we enlisted a pro to tell us if mouthwash is the miracle drain deodorizer we didn't know about.

It makes sense that mouthwash would work to eliminate odors in drains—after all, it eliminates odors caused by food and bacteria in your mouth, so the same must be true of drains, right? To find out, we talked to Joseph Wade, the vice president of operations at Benjamin Franklin Plumbing, who said the hack does work, but only in certain circumstances.

"Mouthwash can be an effective but temporary fix for removing odor from drains," Wade says. "Like with personal hygiene, mouthwash is a great tool to keep our breath fresh and our mouth's bacteria free." 

Mouthwash Can Deodorize Drains, But Not All Types

It's important to know two things about this hack. The first is that it's truly only a temporary fix—don't put off investigating the root cause of the smell, which could indicate a serious issue with your plumbing. The second is that the type of mouthwash matters.

"If you opt to use mouthwash to keep your drains smelling fresh, make sure it is an antibacterial mouthwash," Wade says. "The goal is to eliminate any bacteria that is causing the smell (if that is the root of the issue), and using other mouthwash will not get the job done." Look for the terms 'antibacterial,' 'antimicrobial,' or 'antiseptic' on the bottle to ensure you've got the right kind.

While using an antibacterial mouthwash can help quickly deodorize a smelly drain, there is a catch. "Mouthwash will be a temporary solution to a recurring problem if your drain pipes are not taken care of and cleaned properly throughout the year," Wade says. While it's fine to use mouthwash as a temporary fix to a smelly drain, don't put off investigating the root cause of the malodor and addressing the problem in a more thorough way.

What Causes Stinky Drains — and How to Fix Them

Fortunately, one of the most common causes of odors in drains has a very easy fix. When a drain pipe’s water trap—that's the U-shaped bend in the pipe that you see if you look under your sink—goes dry, resulting in a fetid odor emanating from the drain, solving the problem is as simple as running the water. "The reason the water trap exists is to hold water at all times," Wade explains, "creating a water barrier between your home and all the icky things lurking further down the pipe." 

"If you don't run any water down a particular drain for a very long time, that water can evaporate to the point where sewer smells can make their way through," he says. He advises running the water for several seconds to refill the trap, or, for floor drains, slowly pouring a bucket of water into the drain to restore water to its water trap. 

Refilling the water trap should clear things up within a short timeframe, but if the smell persists, it may be a sign that your drain line needs more maintenance. "If the culprit isn't a dry water trap, there's a chance that a stinky biofilm has built up inside the offending drainpipe," Wade says. "This is more common in kitchen sinks or drains where food or other biological material is regularly washed down the drain."

To clean the drain line, you'll need to remove the drain cover and scrub the interior of the pipe with a flexible pipe brush and a solution of equal parts chlorine bleach and water.

When to Call a Professional

If the drain or drains still smell after trying the mouthwash hack, refilling the water traps, and scouring the pipes to remove biofilm, it's probably time to call in a professional to investigate the root cause. "If the water traps are full and the odor is coming from everywhere, you probably have a bigger problem deeper in the sewer system," Wade says. "This could be a problem with your plumbing equipment or with that of your local sewer authority, so you should consider calling the utility provider to investigate the problem." He says that a sign that the problem is originating from the sewer is when you notice the same smell coming from multiple drains. 

Once you've ruled out a sewer issue, it's time to call in a professional to investigate the problem with your pipes. "If the problem turns out to be on your end, you'll need a professional plumber to track down the source and remedy the problem," Wade says.