Why Your Kitchen Sink Smells, and How to Fix It

Quick answer: A smelly kitchen sink is almost always caused by food scraps, oil and soap building up in the drain and pipe, where they rot. To fix it, clean the drain strainer, scrub the drain opening and the overflow hole with an old toothbrush and dishwashing liquid, then pour a kettle of hot (not boiling) water down slowly. For a slow drain, use a plunger or clean the trap under the sink. Stop it coming back by never pouring oil down the sink and using a strainer every day.

You've washed every utensil, wiped the counter and taken out the bin, and the kitchen still smells. Lean over the sink and there it is: a sour, rotten smell rising from the drain. In Indian kitchens, where we wash oily kadhais, rice pots and dal-coated vessels in the sink several times a day, this is very common. The smell isn't coming from the sink bowl. It's coming from what's stuck below it.

What causes a smelly kitchen sink?

• Oil and ghee. Warm oil goes down as a liquid, then cools and sticks to the inside of the pipe. Food bits and soap stick to it and rot.
• Food scraps. Rice grains, tea leaves, peels and masala bits collect in the strainer and the bend of the pipe.
• Soap scum. Dish soap mixed with hard water and grease forms a sticky film.
• The overflow hole. The small hole near the top of many sinks collects splashes and slime and is almost never cleaned.
• A dry or blocked trap. The U-bend under the sink holds water that blocks sewer smells. If it's damaged, dry or blocked, smells come straight up.

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How to clean a smelly kitchen sink, step by step

1. Empty and clean the strainer. Throw food scraps in the bin, then scrub the strainer with dishwashing liquid and a brush. Food stuck in the mesh is a common source of smell.
2. Scrub the drain opening. Use an old toothbrush and a few drops of dishwashing liquid to scrub as far inside the drain as you can reach, including under the rim of the drain.
3. Clean the overflow hole. Push the toothbrush or a bottle brush into the overflow and scrub. Rinse with warm water.
4. Flush with hot water. Pour a kettle of hot water slowly down the drain. Let it cool slightly from boiling if your pipes are PVC, as boiling water can soften plastic joints over time.
5. Use baking soda for odour. Pour half a cup of baking soda into the drain, leave it for 30 minutes, then flush with hot water. Baking soda helps neutralise odours.
6. Clean the sink bowl. Wash the sink with dishwashing liquid or a surface cleaner and dry it, especially steel sinks, to avoid water spots.

Does baking soda and vinegar really clean drains?

The fizzing looks impressive, but most of the reaction happens at the top, and the two mostly neutralise each other. Baking soda alone is useful for absorbing odours, and hot water does most of the work of loosening fresh grease. For a real build-up, the most effective fixes are physical: cleaning the trap, using a plunger or a drain snake.

How to clear a slow kitchen drain

• Plunger. Fill the sink with a few centimetres of water, cover the overflow hole with a wet cloth, and plunge firmly 10 to 15 times.
• Clean the trap. Put a bucket under the U-bend, unscrew it by hand, empty the gunk, rinse it out and screw it back tightly. Check for leaks afterwards.
• Drain snake. A cheap plastic drain cleaning strip pulls out hair and grease from deeper in the pipe.
• Call a plumber if water backs up into the sink or the smell is coming from a leak or a dry trap.

Why we avoid harsh drain cleaners

Many drain openers rely on strong caustic or acid chemicals. They can burn skin and eyes, release harsh fumes in a small kitchen, damage old pipes, and are dangerous if mixed with other cleaners or if they splash back. In a home with children, a bottle under the kitchen sink is also one of the most common accidental poisoning risks. For everyday smell and slow draining, the gentle steps above usually work. If you do use a drain opener, follow the label exactly, wear gloves and never mix it with anything else.

How to stop the smell coming back

• Never pour oil or ghee down the sink. Wipe oily kadhais with a paper towel or old newspaper first, and collect used oil in a jar for the bin.
• Use a strainer every time and empty it into the bin after each wash.
• Scrape plates into the bin before washing.
• Flush with hot water at the end of the day after the last wash.
• Scrub the drain and overflow once a week.
• Run water in rarely used sinks once a week so the trap doesn't dry out.

Is it the sink, or something else?

If the sink is clean and the smell stays, check the bin, the dishcloth and the sponge, which can smell sour within a day or two. Wash dishcloths daily and let them dry fully, and replace sponges often. For other natural ways to keep the kitchen smelling fresh, see our guide to keeping your home smelling fresh.

What we use

Our Plant Based Dishwashing Liquid uses orange peel enzyme extract with coconut and palm surfactants to break down oil on utensils before it reaches the drain, and it's what we use to scrub the strainer and drain opening. Our Glass & Multi-Surface Cleaner keeps the sink, tiles and counters clean. Both are 100% biodegradable and independently lab tested. For stubborn kitchen grease, read how to remove Indian kitchen grease.

Frequently asked questions

Why does my kitchen sink smell like rotten eggs?

Rotting food and grease in the drain, or sewer gas coming up through a dry or damaged trap. Clean the drain and trap first. If the smell continues, ask a plumber to check the trap and pipes.

How do I get rid of a smelly kitchen drain naturally?

Scrub the strainer, drain opening and overflow with dishwashing liquid, pour in half a cup of baking soda for 30 minutes, then flush with a kettle of hot water.

Can I pour boiling water down my sink?

Hot water helps loosen grease. If your pipes are PVC, let the water cool a little from boiling, as repeated boiling water can weaken plastic joints.

Is it OK to pour oil down the kitchen sink?

No. Oil cools and sticks inside the pipes, trapping food and causing smells and blockages. Collect it in a jar and put it in the bin.

How often should I clean my kitchen drain?

Empty the strainer daily, flush with hot water every night, and scrub the drain and overflow once a week.

Are chemical drain cleaners safe?

They are strong and can burn skin and eyes, release fumes and damage pipes. Use gentle methods first, and if you use one, follow the label exactly and never mix it with other products.