How to Unblock a Kitchen Sink (Without Calling a Plumber)
Start gentle and step up. This guide shows how to unblock a kitchen sink in six levels, from clearing the plughole to using a drain snake, and when to call a plumber.
Water sitting in the sink and refusing to drain? The good news is that you can usually unblock a kitchen sink yourself, and the trick is to start with the gentlest fix and only step up when it doesn’t work.
Most kitchen clogs are a mix of grease, food scraps and soap that has set into a sticky plug. It builds up slowly, then one day the water simply stops.
This guide is set out as a ladder. Each level takes a little more effort than the last. Try them in order, and stop as soon as the water runs freely.
Before you unblock a kitchen sink
A few minutes of prep saves a lot of mess later.
- Bail out standing water with a cup or jug into a bucket, so you can see the plughole.
- Clear the cupboard under the sink. You may need to reach the pipes, and things will get wet.
- Put on rubber gloves. Old sink water is not pleasant.
- Check if it’s just the kitchen. If the bathroom sink, shower or toilet is also slow, the blockage is probably further down the main drain. Skip to the plumber box below.
One rule before anything else: if you’ve already poured in a chemical drain cleaner, don’t plunge or open the trap. The liquid can splash onto your skin or into your eyes. Flush it with plenty of cold water first, or call a professional.
Level 1: Clear the plughole and strainer
Start with what you can see. Lift out the strainer or plug, then pull out any food, hair or gunk trapped around the opening.
A bent wire coat hanger or a cheap plastic drain hair-catcher strip can hook out debris sitting just below the surface.
Run the tap for 30 seconds. Sometimes that’s all it takes to unblock a kitchen sink. If it drains, you’re done. If not, move up a level.
Level 2: Hot water and dish soap
Grease is the most common cause of kitchen clogs. Warmth helps soften it.
- Squeeze a generous squirt of dish soap into the plughole.
- Pour a kettle of very hot water down slowly, in two or three stages.
- Wait five minutes and run the tap.
If your pipes are plastic, use water that’s hot from the kettle but not at a rolling boil, since boiling water can stress PVC joints over time. Repeat once if the water starts to move but is still slow.
Level 3: Use a plunger to unblock a kitchen sink
A plunger is the single most effective tool to unblock a kitchen sink, but technique matters.
- Use a flat-bottomed sink plunger, not a toilet plunger with a flange.
- If you have a double sink, block the other plughole with a wet cloth or a stopper. Otherwise the pressure just escapes through it.
- Cover the overflow hole with a damp cloth too, if your sink has one.
- Leave 5 to 10 cm of water in the sink so the cup seals.
- Push down gently first to push out air, then pump firmly up and down 15 to 20 times, keeping the seal.
- Pull it off sharply and see if the water drains.
Try two or three rounds before you give up on this level. Many blockages break up on the third go.
Level 4: Clean out the trap
The trap is the U-shaped or bottle-shaped pipe directly under the sink. It’s designed to hold water and stop smells, but it also catches debris.
- Put a bucket and an old towel underneath.
- Unscrew the large plastic nuts by hand. They’re usually hand-tight.
- Lower the trap and tip the contents into the bucket.
- Clean it out with an old brush and hot soapy water.
- Check the washers are seated, then screw it back on firmly by hand.
- Run the tap and check for drips.
While you’re under there, it’s a good moment to tidy up. Our guide to organizing under the kitchen sink has ideas that leave room to reach the pipes next time.
Level 5: Use a drain snake
If the trap was clear, the clog is further along the pipe. A hand-cranked drain snake (also called an auger) reaches it.
With the trap removed, feed the end of the snake into the pipe that goes into the wall. Turn the handle as you push. When you feel resistance, keep turning to break up or hook the blockage, then pull it back out slowly.
Refit the trap and flush with hot water. For deep clogs, this is usually the level that finally works when you unblock a kitchen sink at home. A flexible plastic drain stick with barbs is a cheaper option for clogs close to the trap.
Level 6: Check the dishwasher and garbage disposal
Sometimes the sink isn’t the real problem. A dishwasher drain hose often joins the sink waste, so a blockage there can back up into the bowl.
- Garbage disposal: turn it off at the switch and unplug it if you can. Never put your hand inside. Use the hex key in the slot underneath to free the motor, then press the reset button.
- Dishwasher: clean the filter at the bottom of the machine and check the drain hose for kinks. If the dishwasher itself isn’t draining well, our guide on a dishwasher not cleaning properly covers the filter and spray arms.
Do baking soda and vinegar work?
They can help with a slow sink that has mild buildup. Pour half a cup of baking soda down the drain, follow with a cup of vinegar, wait 15 minutes, then flush with hot water.
The fizzing loosens light residue. It won’t shift a solid grease plug or a lump of food, though. Treat it as a maintenance trick rather than a fix for a full blockage.
What about chemical drain cleaners?
Shop-bought drain cleaners are strong and often caustic. They can damage older pipes, harm your skin and eyes, and they don’t always reach the clog.
If you use one, follow the label exactly, ventilate the room and wear gloves and eye protection. Never mix two different drain products, and never combine bleach with vinegar or ammonia.
In most cases, the plunger and the trap are safer ways to unblock a kitchen sink and are just as effective.
When to call a plumber
Several drains in the house are slow or blocked at the same time.
Water comes up in another sink, the shower or the toilet when you run the kitchen tap.
You can smell sewage, or there’s a leak under the sink you can’t stop.
You’ve worked through every level and the sink is still blocked.
You’ve already used a chemical cleaner and it hasn’t cleared.
How to stop it happening again
Once you unblock a kitchen sink, a few habits keep it clear.
- Never pour grease, fat or oil down the sink. Let it cool, then scrape it into the trash. The EPA’s SepticSmart kitchen tips also warn against putting cooking oil and grease down the drain.
- Scrape plates into the trash or compost before washing.
- Use a sink strainer and empty it daily.
- Flush with hot water after washing greasy pans.
- Run the disposal with cold water, and avoid fibrous peels, coffee grounds and eggshells.
A clean, fast-draining sink also helps keep pests away. Food debris in the drain is a common breeding spot, which is why our guide to getting rid of fruit flies in the kitchen starts with the plughole.
Quick summary: the ladder at a glance
| Level | Fix | Best for |
|---|---|---|
| 1 | Clear the plughole | Visible food and debris |
| 2 | Hot water and dish soap | Soft grease buildup |
| 3 | Plunger | Most everyday clogs |
| 4 | Clean the trap | Debris caught under the sink |
| 5 | Drain snake | Clogs further into the pipe |
| 6 | Dishwasher or disposal check | Backups linked to appliances |
Frequently asked questions
What is the fastest way to unblock a kitchen sink?
A sink plunger used with a good seal and the second plughole blocked clears most clogs within a few minutes.
Can I use boiling water to unblock a kitchen sink?
Hot water helps soften grease. With plastic pipes, use water that’s very hot but just off the boil to avoid stressing the joints.
Why does my kitchen sink keep blocking?
Repeated clogs usually come from grease and food scraps going down the drain. Use a strainer, scrape plates first and clean the trap every few months.
Should I use a toilet plunger on a sink?
It’s better not to. A toilet plunger has a flange that doesn’t seal well on a flat sink, and it carries bacteria from the toilet.
