A bad smell coming from your sink is unpleasant, but it's rarely a sign of a serious plumbing problem. In most cases, it means something is trapped in the pipe and slowly decomposing. Here's what's usually behind it and how to get rid of it for good.
Food and grease buildup
In kitchen sinks, small bits of food and grease that make it past the strainer collect on the pipe walls over time. As they break down, they release the sulfur-like smell many people describe as "rotten eggs" or "sewage."
Hair and soap scum
In bathroom sinks, hair combines with soap residue to form a sticky mass that traps moisture and bacteria — a perfect environment for odor-causing buildup.
A dry P-trap
Every drain has a curved pipe underneath called a P-trap that holds a small amount of water to block sewer gas from rising up into your home. If a sink hasn't been used in a while, that water can evaporate, letting odors through. Running the tap for a minute usually resolves this instantly.
How to actually clear the smell
Air fresheners and drain covers only mask the odor — they don't remove what's causing it. To get rid of the smell at the source:
- Run hot water down the drain for 30 seconds to refill the P-trap and loosen grease
- Use a deodorizing drain cleaning powder to break down the buildup and neutralize odor-causing bacteria, not just cover the smell
- Follow with a strainer going forward so food and hair stop collecting in the first place
When it keeps coming back
If the smell returns within days of cleaning, buildup has likely accumulated further down the pipe than a quick rinse can reach. A monthly treatment with a fast-acting powder keeps the whole line clear, not just the section near the drain opening.
Our Drain Cleaner & Pipe Unblocker Powder is built with a deodorizing formula specifically to clear buildup and eliminate odor at the source, not just mask it.
Related reading: What Causes Bad Drain Odours? and Kitchen vs. Bathroom Drains: Why They Clog Differently (And How to Treat Each).