To clean a kitchen sink drain, pull out the strainer basket and scrub it, scrub the drain opening and the underside of its rim with a small brush, then flush with hot water. Do that weekly. If a smell keeps coming back, the gunk is in the P-trap under the sink, and that needs taking apart and rinsing out.
Most kitchen drain smells come from food stuck somewhere you can't see from above: under the strainer's rim, on the underside of a rubber stopper, or in the curved pipe under the sink. Cleaning the visible metal ring doesn't touch any of those.
The weekly drain clean#
- Run the tap for a moment, then lift out the strainer basket or stopper.
- Knock the scraps into the bin. Scrub the basket inside and out with dish soap and a stiff brush, including the underside and any rubber seal. That seal is often the worst part.
- Use a small bottle brush or an old toothbrush on the drain opening. Reach down as far as the brush goes and scrub the inside of the drain throat and the lip where the basket sits.
- Flush with hot tap water for 30 seconds or so.
- Put the basket back.
Keep that brush with your cleaning supplies, away from the dish brush. It's handling the same stuff the bin does.
If you have a garbage disposal, the job is different. Its rubber splash guard collects a thick, gray film on the underside, and the grinding chamber needs its own routine. Never put your hand in a disposal; see disposal-specific cleaning for how to do it safely.
How to clean the P-trap#
If the drain still smells after a good weekly clean, or drains slowly, the U-shaped pipe under the sink is the next stop. It holds a bit of water on purpose, to block sewer gas, but food and grease settle there too.
- Clear out the cabinet and put a bucket or washing-up bowl under the trap. Have old towels and rubber gloves ready.
- Loosen the two slip nuts on either side of the U-bend. Plastic ones usually unscrew by hand; use slip-joint pliers if they're tight, gently, so you don't crack them.
- Pull the trap off and let it drain into the bucket. Expect a smell.
- Scrub the inside with a bottle brush and hot soapy water. Clear any gunk from the pipe stubs it connects to.
- Check that the rubber or plastic washers are seated, then refit and hand-tighten the nuts.
- Run the tap hard for a minute and feel the joints with a dry paper towel. If it's damp, tighten a quarter turn.
Do this every few months as routine, or whenever the smell returns. If your dishwasher drains into the sink plumbing, a dirty trap can affect it too, and the dishwasher's own filter is a common smell source; it's covered in dishwasher maintenance.
Stop feeding the drain grease#
Grease is the one thing to keep out of a kitchen drain, and the usual tricks don't make it safe. Thames Water puts it plainly: running hot water after it doesn't help, because the water cools as it travels and the fat hardens and sticks to the pipe. Washing-up liquid doesn't break it down either. Cooled cooking oil shouldn't go down the sink.
What works:
- Let fat cool and harden in the pan, then scrape it into the bin.
- Pour liquid oil into a jar or bottle with a lid and put it in the trash, or take it to an oil recycling point if your area has one.
- Wipe greasy pans and plates with a paper towel before washing them.
- Keep the strainer in whenever you're doing dishes.
The easiest version: keep an old jar with a lid next to the stove for fat, and bin it when it's full.
Does baking soda and vinegar clean a drain?#
It's fine for freshening the drain opening. Pour in half a cup of baking soda, follow with a cup of vinegar, wait a few minutes, and flush with hot water. Don't expect it to clear a grease clog or anything that's already backing up.
Two rules about chemicals in drains. Don't mix drain cleaners, and don't add bleach to a drain that already has a cleaner in it. The Washington State Department of Health lists drain cleaners among the acidic products that release chlorine gas when mixed with bleach, alongside vinegar. If you've already poured a commercial product down a drain that's still blocked, tell the plumber what it was before they open the pipe, because it may still be sitting in the trap.
Signs the problem is deeper than the sink#
Thames Water lists slow drainage and bad smells as signs of a blockage, and warns that wastewater that can't flow away can come back up through a sink. Call a plumber, or your landlord, if:
- The sink drains slowly even after you've cleaned the trap.
- Water backs up into the sink when the dishwasher or washing machine empties.
- Other drains in the house are slow at the same time, which points to a blockage further down the line.
- You hear gurgling from the drain when other fixtures run.
Plunging a kitchen sink is fine to try first, unless you've already poured a chemical drain cleaner in; plunging can splash it back at you. If you have a double sink, block the other drain with a wet cloth or stopper so the plunger has something to push against.
Keep the rest of the area clean too#
The drain is often blamed for smells that come from the bin under the sink. If cleaning the drain doesn't fix it, check the kitchen trash can, especially the bottom of the outer shell, before going further. While you're at the sink, unscrew and rinse the faucet aerator if the water stream has started spraying sideways.
A weekly ChoreLists.com reminder for the strainer and a quarterly one for the P-trap covers almost every kitchen drain.