A bad smell after using a drain cleaner usually happens because the chemicals are breaking down a clog, disturbing trapped bacteria, or releasing toxic fumes. Immediately ventilate the room by opening windows and turning on fans. Do not pour any other chemicals—especially bleach or ammonia—into the drain, as this can create deadly gases.
Smelly drains are almost always caused by a buildup of hair, soap scum, or food waste (biofilm) trapped inside the pipe, or a dry P-trap allowing sewer gases to escape. To fix the odor, you can scrub the upper drain, dissolve the grime with a natural cleaner, or manually clean the pipe underneath the sink.
Pouring salt down your drain at night is a popular DIY plumbing trick used for routine maintenance. The goal is to take advantage of the salt's coarse texture and natural moisture-absorbing properties.
Bacterial growth: Inside your drain, there are bacteria that feed on organic matter. Static water can build up in the P-trap, the U-shaped pipe beneath the drain, when the bathroom fixture doesn't run for a while. This stagnant water turns into a haven for germs, which give out foul smells.
You can also deodorize drains and help smelly drains with a combination of baking soda and vinegar. These ingredients, when used together, can also sometimes help to clear drain clogs.
Baking soda and vinegar do not effectively unclog drains. Instead of clearing debris, mixing them chemically neutralizes both ingredients into salt water. The fizzing reaction is visually satisfying but largely escapes upwards, offering zero power to dissolve grease, hair, or stubborn sludge.
How to stop the smell
Here are some top-rated options:
The characteristic "old age smell" is scientifically known as nonenal (or 2-nonenal). It is a chemical compound produced when the skin's natural oils and fatty acids break down and oxidize as we age.
[4,5] In the case of low levels of exposure (0.05 ppm), early signs and symptoms include the smell of rotten eggs, fatigue, headaches, nausea or vomiting, dizziness or lightheadedness, and poor memory and concentration.
Plumbers highly recommend avoiding harsh chemical drain cleaners, as they can corrode pipes and only offer temporary relief. Instead, they suggest preventing buildup through daily habits, using natural enzyme or enzymatic cleaners for maintenance, and letting professional cleaners clear severe blockages.
Salt itself will not chemically damage PVC pipe; the material is chemically inert and highly resistant to saltwater and brine. However, salt can indirectly cause issues for your plumbing system. While the plastic remains unaffected, salt can corrode connected metal fittings, dry out joints, or potentially damage downstream fixtures like water heaters.
Pouring an occasional glass of soda down the drain won't cause immediate damage, but making it a habit is bad for your plumbing. The high sugar content creates sticky residue that traps debris, while the acid can corrode older metal pipes and harm septic systems over time.
To instantly get rid of a drain smell, start by flushing the pipe with a kettle of boiling water. Follow up by pouring 12one-half12 cup of baking soda down the drain, chasing it with 12one-half12 cup of white vinegar, and covering it. Let it fizz for 15 minutes before rinsing with hot water.
9 ways to unclog a drain without a plumber
It is not recommended to pour bleach down your sink to eliminate odors. While it temporarily kills surface bacteria, bleach is corrosive to pipes, can ruin the rubber seals in your plumbing, and will not dissolve the underlying grime—like hair and soap scum—that causes the smell.
The first thing is to make sure the smell is sewer gas which is usually a rotten egg smell and not a natural gas smell which usually smells like a skunk.
Symptoms of carbon monoxide poisoning include:
"Sewage poisoning" refers to health complications caused by inhaling toxic sewer gases (like hydrogen sulfide and ammonia) or ingesting water/food contaminated with raw sewage. Symptoms range from mild gastrointestinal distress to severe nervous system issues.
"Old person smell" can begin as early as age 40, as the body produces more of the compound 2-nonenal. This, often described as a grassy, greasy, or musty odor, is a natural part of aging caused by the breakdown of unsaturated fatty acids and declining skin antioxidant defenses. While it starts around 40, it becomes more noticeable in the 50s and beyond.
A declining sense of smell is strongly linked to dementia and Alzheimer's disease. Because olfactory and memory pathways are heavily intertwined, damage to these areas often precedes typical cognitive symptoms. Testing a person's ability to identify and distinguish different odors serves as an important, non-invasive early warning sign.
To get rid of "old person smell," you need to use soaps specifically formulated with Japanese persimmon extract and green tea. Standard body soaps, scrubs, and perfumes are typically ineffective against this odor.
Hydrojetting Tools for Drain Clogs
What do plumbers use to clean drains? For hard-to-reach or tough drain clogs, your plumber may opt for hydrojetting, a modern technique that uses pressurized water to break apart, dislodge, and flush stubborn clogs in your sewer lines or drain line.
For a quick and natural way to freshen a smelly drain, pour 1/2 cup of baking soda down the sink, followed by 111 cup of white vinegar. Let the mixture fizz for 10 to 15 minutes to break down grime, then flush the pipes thoroughly with a kettle of boiling water.
Items to Never Flush or Pour Down the Drain: