What causes a kitchen sink smell
Most smells from a kitchen sink start just below the plughole. All the waste water from washing up passes through the bottle trap, and anything that settles there begins to rot. Work through these causes in order:
- Grease and food in the trap. Oil, fat, rice grains and small food scraps collect in the lower section of the bottle trap and give off a sour smell.
- A dry or loose trap. A sink left unused for some time, or a trap that is not screwed on fully, can let smells rise from the pipe.
- A choked branch pipe. When grease builds up in the pipe beyond the trap, the sink drains slowly and the smell comes back soon after you clean the trap.
- A smelly floor trap nearby. If your kitchen has a floor trap close to the sink, its smell can seem to come from the sink.
HDB says not to pour cooking oil into the sink, as the oil solidifies and chokes the pipe (HDB guide to floor traps). Let used oil cool in a container and put it in the bin instead.
Clean the bottle trap
HDB's home care guide gives these steps to clear a choked bottle trap (HDB guide to sinks and wash basins). Use the same steps to clean out a trap that smells.
- Twist off the lower section. Turn the lower section of the bottle trap anti-clockwise to remove it.
- Clear the debris. Use a wire hook to clear the debris from the trap.
- Flush with water. Flush the trap with water.
- Screw it back. Screw the lower section back clockwise.
Once the trap is back on, run the tap for a short while and watch the trap and the pipe joints underneath. If water drips after you refit it, see the guide to a kitchen sink leaking underneath.
If a sink trap smell is still there after cleaning, check that the lower section is screwed on fully. If it is, the problem is probably further along the pipe.
Keep grease out of the pipe
The less grease that goes down the sink, the less there is to collect in the trap and the pipe. Wipe greasy pans, woks and plates with kitchen paper before you wash them, and scrape food scraps into the bin. A sink strainer over the plughole catches rice and small bits.
HDB advises pouring degreaser into the sink discharge pipes regularly to prevent the accumulation of oil and grease, and keeping the floor trap grating closed (HDB guide to floor traps). Follow the instructions on the product label. Never mix bleach with acid-based cleaners or ammonia.
If the sink smells like sewage rather than old food, the smell may be coming from the floor trap, not the sink. HDB's advice for a smelly floor trap is to remove particles, flush water into the trap, and seal the floor trap when you are away for a long time (HDB guide to floor traps). For smells from drains in the bathroom, see the guide to bathroom drain smell.
Who can fix it
You can clean the bottle trap yourself. Get help if the trap is cracked, the smell keeps coming back or the sink still drains slowly after cleaning.
PUB lists installing or replacing a washbasin or sink and its bottle trap as a simple plumbing work that a handyman may do. Other water service and sanitary plumbing works need a PUB Licensed Plumber (PUB: Plumbing Works).
For a choke in the branch pipe, call a licensed plumber. If the sink also drains slowly, the guide on how to unclog a kitchen sink explains what you can try first. When you book, describe the smell, how fast the sink drains and what you have already tried, and ask whether the visit includes checking the pipe beyond the trap.
What a plumber charges
The table below shows the published rates for sink trap work, as each company prints them.
FROM THE HOMEZYPRO DIRECTORY
Published bottle trap replacement rates
For the most common unit (per job), the lowest published bottle trap replacement rates from 10 companies run from S$40 to S$100 per job (middle rate S$50), to replace one kitchen sink trap. The middle figure is a real published rate, not an average. Each figure is one company's own advertised rate with its conditions, not a quote.
See 10 published bottle trap replacement rates and sources
| Company | Service as listed | Rate | Source |
|---|---|---|---|
| Plumber - Singapore Plumbing 24hrs | Supply & Replace Water Trap for Kitchen Sink | From S$40 per job | singaporeplumbing24hrs.com.sg |
| GD Plumbing | Replace bottle trap for kitchen sink | From S$50 per job | gdplumbing.com.sg |
| Home Plumbers Singapore | Supply and replace a kitchen-sink bottle trap | From S$50 per job | homeplumbers.com.sg |
| SG1 Plumber Singapore | Sink Bottle Trap Replacement | S$50 per job | sg1plumber.com |
| Sin Plumbing Singapore | Supply & replace bottle trap for kitchen sink | From S$50 per job | sinplumbing.com |
| Uncle Plumber | Supply and Replace bottle trap for kitchen sink | From S$50 per job | uncleplumber.sg |
| Kiasu Plumber | Supply & install bottle trap (kitchen sink) | From S$80 per job | kiasuplumber.com |
| Best Plumbing | Supply & replace bottle trap for kitchen sink | From S$100 per job | bestplumbing.com.sg |
| SR Power Plumber Pte. Ltd. | Supply & replace bottle trap for kitchen sink | From S$100 per job | srpowerplumber.com |
| Summer Plumbing Service | Supply & replace bottle trap for kitchen sink | From S$100 per job | sgplumbing.com.sg |
10 companies publish a rate to replace a kitchen sink bottle trap, and all 10 price it per job. Their published rates run from S$40 to S$100 per job, as printed. S$50 per job sits in the middle of the list: both middle companies print S$50, so it is a real published rate. Each line covers replacing one kitchen sink trap, so check what each price covers.
NEXT STEP
See plumbing companies in the directory with their published prices, the areas they say they cover and their sources.
Compare plumbersA choked branch pipe is quoted separately and is not covered by these rates. Compare choked drain plumbers for that job. For bigger jobs, PUB advises getting itemised quotations from at least three Licensed Plumbers (PUB: Plumbing Works).
Questions
Does baking soda and vinegar fix a smelly sink?
Not on its own. Baking soda and vinegar may loosen light residue in the trap, but they do not clear a choke in the trap or the pipe. For a smell from the trap, clean the bottle trap by hand as set out above. Do not add bleach or other cleaners to the mix. Never mix bleach with acid-based cleaners or ammonia.
Why does my sink smell only at night?
Usually because the sink has not been used for some hours. Smells from the trap and pipe can collect while no water runs through them. Run the tap for a short while before you go to bed and again in the morning. If the smell stays strong, clean the bottle trap as set out above.
Can a dishwasher make the sink smell?
Yes, it can. Food caught in a dishwasher's filter or drain hose can start to smell, and the smell may seem to come from the sink. Clean the filter and look along the drain hose for trapped waste or kinks, following the maker's manual. If the smell stays, ask the maker or a plumber to check the hose and its connection.
Should I pour boiling water down the sink?
No. Use hot tap water instead. Hot water can soften fresh grease, but boiling water can damage some plastic pipes. Run hot tap water for a short while after you wash greasy pans, and keep cooking oil out of the sink altogether. If the sink still drains slowly, the pipe may need clearing by a plumber.
Why does the smell come back after cleaning the trap?
Usually because the choke is further along the pipe. Grease that has built up in the branch pipe beyond the trap keeps smelling after the trap is clean. Check that the lower section of the trap is screwed on fully, then call a plumber to clear the pipe. Ask for a separate quote, as this is not trap replacement work.
Is a sink smell a sign of a gas leak?
Not usually. A sink smell tends to be sour, like old food or sewage, while gas has a distinct smell of its own. If you think you smell gas, treat it as a possible gas leak, not a drain problem, and follow the steps in City Energy's gas leak guide.
- HDB guide to floor traps
- HDB guide to sinks and wash basins
- PUB: Plumbing Works
- City Energy's gas leak guide
Prices come only from the sourced company rates in the HomezyPro directory, shown with each company and its source.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
How HomezyPro worksYOUR NEXT STEP
Find the right team for your home.
Compare services, published prices and sourced reviews. Contact the company directly to confirm your job and availability.
Explore plumbing companies