If your P-trap is smelling, it is likely either dry (letting sewer gases escape) or filled with rotting organic debris like hair, soap scum, and bacteria.
To fix a smelly P-trap, you can typically resolve the issue using one of three simple methods: refilling a dry trap, flushing the pipe with natural cleaners, or removing the P-trap to physically clean out gunk.
When a drain is not used often, the water in the P-trap can slowly evaporate. Once the trap dries out, sewer gases can escape into indoor spaces and cause unpleasant odors.
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.
Step 2: Refill the Trap
Turn on the hot water tap for the affected basin, sink or shower. Let the water run for 1 to 2 minutes. This is usually enough to fully restore the water level and re-establish the seal.
People pour salt down the drain at night primarily for routine maintenance. The coarse texture acts as a gentle abrasive to scour away minor grease, soap scum, and grime, while the overnight window gives it time to absorb moisture and loosen buildup before being flushed away.
P-traps can dry out as quickly as a month, sometimes even less than that. This happens most often in winter. To prevent your P-trap from drying out, run the sink or shower for a minute or two once a week to keep water flowing and your P-traps from drying out.
"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.
The best fancy word for a disgusting smell is malodorous. Depending on the specific type of foul smell you are trying to describe, you can also use these elegant alternatives:
"Old person smell"—scientifically known as 2-nonenal—is caused by fatty acids oxidizing on the skin. Because it is not water-soluble, standard body washes and intense scrubbing won't wash it off. To eliminate it, you need to use soaps containing Japanese persimmon extract and green tea.
The Fix: Pour about a gallon of water down the pipe. If you're dealing with a dry p-trap, this should fix it. If you still smell sewage, call a plumber to make sure it and your drain pipe have been properly installed.
Plumbers recommend starting with a DIY enzyme or baking soda and vinegar flush to break down organic buildup. If that fails, they advise physically scrubbing the drain walls or using commercial enzyme cleaners. If the smell resembles sewage, the pipe’s P-trap may be dry or blocked, requiring professional inspection.
A shower trap stops foul sewer smells from entering your bathroom by holding a small amount of water in a U- or P-shaped bend. This water sits in the pipe and acts as an airtight seal, completely blocking odorous sewer gases from traveling backward into your home.
Tip 4: Try an Enzymatic Cleaner
Enzymatic cleaners bind with and destroy the uric acid. The enzyme products that work well have the correct combination of enzymes and other ingredients to destroy the uric acid crystals. It also eliminates the bacteria surrounding the urine that causes the odor.
Cleaning out a P-trap (the U-shaped pipe under your sink) is a straightforward process. You will need a bucket, adjustable pliers (or a wrench), and an old toothbrush.
Another sign to watch for is recurrent clogs or slow drainage, which might suggest a blockage or structural problem within the P-trap. Additionally, visible signs of wear, such as corrosion or leaks, are clear indicators that the P-trap is nearing the end of its lifecycle.
"Old lady smell" is caused by 2-nonenal, an oily compound formed when skin fats oxidize. Because it is not water-soluble, it cannot be scrubbed away with regular soap. Eradicate it by switching to persimmon extract soap, laundering fabrics in vinegar, and limiting heavy dietary fats.
"Old person smell" (clinically called Nonenal) is caused by the oxidation of fatty acids on the skin as people age. Because it is oil-based, regular soap and water won't wash it away. You need specialized products containing Japanese Persimmon Extract (tannins) and Green Tea, which naturally break down and neutralize these stubborn odor molecules.
If you practice good hygiene but still notice an unpleasant smell, the cause is usually internal or environmental, rather than a lack of cleanliness. Sweat itself is actually odorless; the smell occurs when naturally occurring bacteria break down proteins and fatty secretions on your skin.
Certain foods cause bad body odor when their volatile compounds, sulfur, or fats are broken down by the body and secreted through sweat. As these byproducts mix with the natural bacteria on your skin, they produce an unpleasant smell.
Synonym Chooser
Some common synonyms of stinking are fetid, fusty, malodorous, musty, noisome, putrid, and rank. While all these words mean "bad-smelling," stinking and fetid suggest the foul or disgusting.
Diabetic sweat typically smells sweet, fruity, or similar to acetone (nail polish remover). This distinct odor is caused by a buildup of ketones, which occurs when the body burns fat for energy instead of glucose.
Elderly individuals typically lose their sensitivity to sweet and salty tastes first.
Certain vitamins and supplements can help reduce body odor by altering your skin's pH, boosting immune responses to odor-causing bacteria, or improving digestion and liver function.
The "old grandma's smell" (or old person smell) is a genuine biological phenomenon known as nonenal. Described as a musty, grassy, or greasy odor, it is caused by the chemical breakdown of fatty acids on the skin and is completely unrelated to personal hygiene.