The short answer
A smelly sink drain in a Northern Virginia house is usually one of four things. Gunk growing in the overflow and on the stopper of a bathroom sink. Food in the disposal or the trap of a kitchen sink. A dry trap letting sewer gas through, on a sink nobody uses. Or a vent problem that keeps the trap from holding its water. One quick test first: if the rotten egg smell comes only with hot water, it’s the water heater, not the drain.
What the smell is telling you
Swipe to see all columns →
Swipe to see all columns →
| What you smell | Where | Usually |
|---|---|---|
| Musty, sour or swampy | Bathroom sink | Gunk in the overflow and on the pop-up stopper |
| Rotting food | Kitchen sink | The disposal’s rubber flaps, or food sitting in the trap |
| Sewer, like a portable toilet | A sink that’s rarely used | A dry trap |
| Sewer, and the sink gurgles | Any sink | A vent that’s blocked or missing |
| Rotten eggs, hot water only | Any faucet | The water heater’s anode rod (the fix) |
| Sewer, all over the house | Everywhere | A bigger leak in the drain system (start here) |
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Bathroom sink: the overflow and the stopper
The little hole near the rim of a bathroom sink is the overflow. Behind it is a channel that gets splashed with toothpaste, soap and hair and never gets rinsed, and that film is what smells. The pop-up stopper collects the same stuff on its stem.
- Under the sink, find the nut on the back of the drain pipe where a rod goes in. Unscrew it, slide the rod out, and the stopper lifts out of the drain.
- Scrub the stopper. It’s usually gross.
- Push a bottle brush into the overflow hole and scrub. Do the drain opening too.
- Pour a kettle of hot water down the overflow, then put it all back and run the tap.
A cup of white vinegar down the overflow helps with what the brush can’t reach. Baking soda and vinegar is fine for a smell. It just won’t clear a clog. If the sink is slow too, a slow bathroom sink walks through the stopper and the trap.
Kitchen sink: the disposal and the trap
Flip up the rubber flaps in the disposal opening and look at the underside. That’s where most kitchen smells live. Scrub them with an old toothbrush and dish soap. Then run the disposal with cold water and a handful of ice, which knocks loose what’s stuck to the grinding chamber, and run the water another half minute after it’s done.
If it still smells, food and grease are sitting in the trap or further down the line. A kitchen sink that smells and drains slowly is close to a clog. Kitchen sink backing up covers that, and what never goes down a drain keeps it from starting. One more spot: if the dishwasher drain hose doesn’t loop up high under the counter, dirty sink water can run back into the dishwasher and sit there.
Sewer gas: the trap and the vent
The bend under every sink, the P-trap, holds a plug of water that keeps sewer gas out of the room. A guest bath or basement sink that sits unused for weeks can dry out, and then the gas comes straight through. The fix is to run the water for half a minute. If that sink sits again, run it again every couple of weeks.
If a sink smells like sewer even though it gets used, listen while it drains. Gurgling, or the trap sucking itself dry, means the drain isn’t getting air. Every drain needs a vent pipe that lets air in behind the water. When the vent is blocked by leaves or a nest on the roof, or there was never a proper one, the draining water pulls the trap empty and the smell follows.
The plumbing vent pipe explains how venting works, and an air admittance valve is the usual fix for a sink that never had a vent. A loose nut or a cracked trap under the sink lets gas out too. You’ll usually see a drip or a damp cabinet floor with it.
What not to do
Don’t pour drain cleaner down a sink that smells but drains fine. A smell isn’t a clog, and drain cleaner is hard on older pipes. Never mix bleach with another cleaner in a drain, because some of those mixes make a dangerous gas. And don’t just cover it with a scented spray. A sewer smell means gas is getting in, and the gas needs to be stopped, not masked.
When it’s time for a plumber
- The smell comes back a few days after you cleaned everything.
- The sink smells and drains slowly, or gurgles.
- More than one drain smells, or the smell is in the basement.
- There’s a damp cabinet floor or a drip under the sink.
Smells are one of the ways a house tells you something’s off. House smells and what they mean covers the rest of them, and error codes and warning lights at home covers the other signals worth acting on.
When you’d rather we do it
A sink clogged at the trap is $99 with our sink clearing offer, up to the P-trap. A toilet, tub, shower or any drain past the trap is drain cleaning, $200 to $800. The main line to the street runs $550 to $1,650, and when grease or roots keep coming back, hydro jetting clears the pipe wall. You get the price before we start. A plumbing diagnosis visit is $49, or $250 after hours.
Call (703) 997-9757, day or night, or see every current deal on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why does my sink drain smell?
Usually gunk in the overflow or on the stopper, food in the disposal or trap, a dry trap on a sink that isn’t used, or a blocked vent. Each one has a different fix.
Why does my bathroom sink smell like sewage?
If it’s rarely used, the trap may have dried out, and running water fixes it. If it’s used every day and gurgles, the vent may be blocked.
How do I get rid of a smelly kitchen sink drain?
Scrub the underside of the disposal’s rubber flaps, run the disposal with ice and cold water, and flush the trap with hot water. A smell that stays means food is sitting further down the line.
Why does my sink smell like rotten eggs?
If it’s only when the hot water runs, it’s the water heater’s anode rod reacting with the water. If it comes from the drain itself, it’s sewer gas or buildup in the trap.
Is a smelly drain dangerous?
Gunk in the overflow is just unpleasant. Sewer gas is different: it means the trap or a seal isn’t doing its job, and it should be fixed rather than covered up.
