Find the source in two minutes
| Where the smell appears | Likely cause | Start with |
|---|---|---|
| From the drain after travel or disuse | A dry or missing P-trap | Run water for a minute, then check the pipe under the sink |
| From the drain, with slow draining | Grease, soap and food build-up | Clean the trap and use a strainer |
| When or after the dishwasher runs | Dishwasher filter or drain water flowing back | Clean the filter and check the drain hose |
| Only inside the sink cabinet | A slow leak or trapped damp in the base | Check each joint with a dry tissue |
| Near the floor, under the cabinets | Floor-cleaning water under the plinth | Dry the area and change how you mop |
| Around the house after cooking | The hood does not vent outside or its filter is saturated | Check the duct and filters |
8 common causes and how to fix each
1. A missing or dry P-trap
The trap is a bend in the drain pipe under the sink that holds a little water, and that water stops sewer gas from rising. If the pipe runs straight with no trap, or the trap dries out after a period without use, the smell comes up through the drain. Fix: run water after travel or long breaks, and if there is no trap, have a plumber fit one that is easy to remove and clean.
2. Grease, soap and food build-up
Grease cools in the pipe and sticks to its walls, then catches food and soap residue that breaks down. Fix: use a strainer in the drain and do not pour frying oil into the sink; let it cool and put it in the bin. Clean a removable trap with a bowl underneath, then run hot tap water for a few minutes. Do not pour boiling water into plastic pipes.
3. The dishwasher
The dishwasher filter collects food, and if it is not cleaned the smell builds up inside and around the machine. Sink water can also flow back into the dishwasher if the drain hose is not fitted as the manufacturer specifies. Fix: clean the filter as the manual describes and fix the hose as instructed, usually with a high loop under the worktop. See the sink and dishwasher drainage requirements.
4. A slow leak under the sink
Small drips from the tap connection or drain wet the cabinet base without being noticed, and in the dark with little air they turn musty. Fix: wipe each joint with a dry tissue while water runs, repair the source, then dry the base fully. A washable liner on the sink cabinet floor makes leaks easier to spot and clean. Metal cabinet bodies do not swell with water, but trapped damp smells in any kitchen, so the real fix is stopping the leak.
5. Materials that absorb moisture around the sink or under the worktop
Wood-based boards with unsealed edges near water can absorb moisture and hold smells over time. Fix: in an existing kitchen, ask a technician to inspect and dry the area or replace the damaged part. For a new kitchen, ask about the sink cabinet body material, what the worktop is fixed on, and how edges are sealed in the wet zone.
6. Floor-cleaning water under the plinth
Pouring a lot of water when cleaning the floor lets it run under the cabinet plinth, where air does not reach and it dries slowly. Fix: use a well-wrung mop and do not push water toward the cabinets. When detailing a kitchen, ask for a water-resistant plinth that can be removed for cleaning.
7. The range hood does not vent outside
A hood without an outside duct recirculates air through its filter, and once the filter is saturated with grease the cooking smell stays in the house. Fix: clean metal filters or replace carbon filters as the manual says, and make sure the duct reaches an outside opening with a cover. See the kitchen ventilation and range hood guide.
8. Waste bins and the fridge drip tray
A bin inside a closed cabinet that is not cleaned regularly, or the fridge drip tray where water collects, are two often-forgotten sources. Fix: use a lidded bin, empty it daily, wash the bin itself, and clean the fridge drain hole and tray as its manual describes.
Cleaning a drain safely
- Start mechanically: the strainer, removing and cleaning the trap, and hot tap water.
- Baking soda and vinegar with hot water may help with light build-up, but they do not fix a missing trap or a full blockage.
- Never mix chemical cleaners, especially bleach with acidic or ammonia-based products, as this can release dangerous gases.
- Follow the label on any drain cleaner, wear gloves and ventilate the kitchen.
When to call a plumber
Call a plumber if the sewer smell continues even though the trap holds water, if the drain gurgles, if water comes back up into the sink, or if a leak appears from the wall or floor. These can point to drain venting or a blockage beyond the trap.
Prevent smells at the design stage
If you are planning a new kitchen, these decisions reduce the chance of smells later:
- A removable trap with comfortable access inside the sink cabinet.
- A cabinet body material that does not swell with water in the sink zone, and protection for the cabinet floor.
- A hood with an outside duct, planned early.
- A ventilated, easy-to-clean place for the waste bin.
To compare materials, see Nano aluminum kitchens and cladding kitchens. Nano customers can request follow-up through the maintenance request form.
Kitchen smell FAQ
Why does my kitchen sink smell like sewage?
The most common cause is a missing or dry P-trap, followed by grease and food build-up in the drain. If the smell continues while the trap holds water, have a plumber check the drain and its venting.
Do baking soda and vinegar fix a smelly sink?
With hot water they may help with light build-up, but they do not fix a missing trap or a full blockage. Do not mix them with other chemical cleaners.
Why is the smell only inside the sink cabinet?
Usually a slow leak from the tap connection or drain, or damp trapped in the cabinet base. Check the joints with a dry tissue and dry the base.
Why does the cooking smell stay in the house even with a hood?
Usually because the hood recirculates air instead of venting it outside, or because its filter is saturated with grease. A hood ducted to the outside removes odors more effectively.