How to Clean a Stinky Kitchen Drain (and Why Bleach Will Not Fix It)

Step by step

1. 1

   Pull out the strainer and wash it

   Put on your gloves. Lift out the strainer basket or stopper and wash it in hot, soapy water. Scrub the underside and the little holes with an old toothbrush.

2. 2

   Scrub inside the drain

   Push a long, stiff drain brush down the drain and scrub up and down, turning it as you go. Work it as far as it will go into the pipe and the curved trap under the sink.

   Texas A&M AgriLife Extension says scrubbing the pipes and traps with a stiff brush is how you get rid of the film, because bleach and drain cleaner barely touch it.

3. 3

   Flush it with hot tap water

   Run the hottest water from your tap down the drain to carry off what you loosened. Use tap water, not a kettle of boiling water. If your drain pipe is plastic, know that Charlotte Pipe, a maker of plastic drain pipe, rates its PVC drain pipe for 140°F at most. Boiling water is 212°F.

1. 4

   At bedtime, pour in the enzyme cleaner

   Follow your bottle’s label. The Drano FlowGuard label says to run warm water for one minute, turn it off and pour in 10 ounces. Then run about 2 more cups of warm water, and do not run any water down that drain for 6 to 8 hours. Bedtime makes the wait easy.

2. 5

   Check the smell in the morning

   After 6 to 8 hours, use the sink as normal and give it a sniff. Keep going with the next step even if it smells better, because one dose will not clear all of the film.

   What it looks like when it is working: a drain that smells like nothing at all when you lean over it.

3. 6

   Repeat until the smell stays gone

   Texas A&M says these products usually need repeat doses over several weeks to clear the film. After the first big dose, the Drano FlowGuard label says to pour 2 ounces down each drain every 2 to 4 weeks.

When it will not work, and what to do instead

Sometimes the drain still smells after all that. Here is what to check.

• You poured bleach or boiling water down it. It makes sense that something that strong would clear it out. But the University of California’s pest program says bleach and boiling water do not remove the film in the drain, so they help for a short time at best. Ohio State says the same about bleach.
• It smells like rotten eggs or sewer. Wisconsin’s health department says that smell is hydrogen sulfide in sewer gas. It can get in through a drain with a dried-out trap or a leaking or blocked roof vent. Run water down drains you rarely use so the traps stay full, and call a plumber if it keeps coming back.
• The sink drains slowly or not at all. That is a clog, not just film. The Drano FlowGuard label says it will not open clogs, so clear the clog first or call a plumber.
• You see little flies around the sink. Texas A&M says drain flies breed in the film inside drains. See Why fruit flies keep coming back.
• You tried baking soda and vinegar. A chemist at the University of Tasmania explains that the two mostly cancel each other out, leaving water, a salt and the fizzy gas. See Does baking soda and vinegar unclog a drain?.

Why it works

That smell is coming from a film that lines the inside of your drain. Ohio State describes it as a bacterial scum of rotting organic matter that forms on plumbing, and rotting food is exactly what your nose is picking up.

The film is sticky and holds on tight, a little like the film on your teeth before you brush. A splash of bleach or hot water runs right over the top of it and on down the pipe. That is why the smell comes right back.

A brush breaks it loose, the same way a toothbrush does. Then the enzyme cleaner goes after what the brush missed. Ohio State says an enzyme product is designed to break the sticky bond that bacteria form on the pipes. It takes a few rounds because the film builds back up between them.

Every one of us has leaned over the sink to rinse a plate, caught that whiff and wondered where in the world it was coming from. You wipe the counter, you take out the trash, and it is still there.