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Best kitchen drain unblockers
How our tests find you the best
Effectiveness
Sick of smelly kitchen drains? We check if each solution can dissolve a greasy, stubborn mix of melted lard, breadcrumbs and broccoli.
Speed
Unblocking a drain is a chore that we all put off. That’s why we tell you how fast each solution works so you can clear the blockage in a flash.
The best kitchen drain unblockers from our tests
All the kitchen drain unblockers we tested worked. However our top pick, the Mr Muscle Power Gel Drain Unblocker, was by the far the fastest to dissolve stubborn food residue and grease in the blocked U-bend we tested it on.
The products below are suitable for food blockages. If you want to unblock a drain clogged with hair, take a look at our pick of the best shower drain unblockers. As with any bleach-based products, make sure you always wear gloves, old clothes and follow the instructions carefully.
If you want to give a home remedy a go, see how our test of bicarbonate soda, salt and vinegar compared.
Compare our results and prices at a glance in our table below, or read on for our full reviews.
| Kitchen drain unblocker | Price | Effectiveness | Speed to unblock drain |
|---|---|---|---|
| Best Buy Mr Muscle Power Gel Drain Unblocker | Asda(£2.98), Sainsbury's(£3.75) and Amazon(£5.96 for two) | Five minutes | |
| Sainsbury's Sink & Plughole Unblocker | Sainsbury's(£2) | 15 minutes | |
| Waitrose Essential Drain Unblocker | Waitrose(£2.45) | 15 minutes | |
| Cillit Bang Drain Odour Eliminator & Unblocker Gel | Asda(£2.47), Ocado(£2.60) and Tesco(£2.60) (Out of stock) | 30 minutes | |
| Soda Crystals | SQUIRREL_TEXT_50013647 | 30 minutes | |
| Ocado Sink & Drain Unblocker Gel | Ocado(£2.25) | Up to three hours | |
| HG Kitchen Drain Unblocker | SQUIRREL_TEXT_50013940 | Up to six hours |
Date tested: May 2021. Page last checked: April 2025. We are not able to show every retailer and cheaper prices may be available.
Best Buy: Mr Muscle Power Gel Drain Unblocker
Our verdict Our top kitchen drain unblocker
Available from Asda (£2.98), Sainsbury's (£3.75), Amazon (£5.50 for two)
Pros
- Clears the pipes
- Works super quickly
Cons
- In the smaller size it's a single-use plastic bottle
Size 500ml, also comes in 1 litre
Speed to unblock drain Five minutes
Suitable for a septic tank Yes
All the drain unblockers tested worked (although, some needed a bit of extra help as we explain), but Mr Muscle Power Gel was easily the fastest.
Within five minutes the clogs in our drains were dissolved.
If getting the job done fast is what's important to you, then have a bottle of this waiting under your sink.
See how it fared in our best shower drain unblocker tests.
Sainsbury's Sink & Plughole Unblocker
Our verdict Good results with a quick turnaround
Available from Sainsbury's (£2)
Pros
- Clears the pipes
- Works quickly
Cons
- Single-use bottle
Size 500ml
Speed to unblock drain 15 minutes
Suitable for a septic tank Yes
It only took 15 minutes for this plughole unblocker from Sainsbury's to cut through the grease and food residue.
Once it had finished, the pipes and U-bend were squeaky clean.
See our pick of the best cleaning sprays and best oven cleaners, tried and tested by our experts.
Essential Waitrose & Partners Drain Unblocker
Our verdict Fast-acting unblocker with consistent results
Available from Waitrose (£2.45)
Pros
- Clears the pipes
- Works quickly
Cons
- Single-use plastic bottle
Size 500ml
Speed to unblock drain 15 minutes
Suitable for a septic tank No
Like many of the other bleach-based products, this unblocker from Waitrose & Partners worked quickly to get rid of the clog.
Cillit Bang Drain Odour Eliminator & Unblocker Gel
Our verdict Decent
Available from Asda (£2.47), Ocado (£2.60), Tesco (£2.60) (Out of stock)
Pros
- Clears the pipes
Cons
- Single-use bottle
Size 500ml
Speed to unblock drain 30 minutes
Suitable for a septic tank The manufacturer says they are unable to test on all septic tanks. Therefore, it's safest for you to check with your septic tank provider.
This unblocker gel from Cilit Bang was not the fastest, but it was by no means the slowest product from our investigation.
It effectively removed the clogs in both of our tests.
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Soda Crystals
Our verdict Effective but difficult to prepare
Pros
- Clears the pipes
- Offers lots of cleaning options
Cons
- Requires more preparation than the others
Size 1kg
Speed to unblock drain 30 minutes
Suitable for a septic tank Yes
Soda Crystals worked, but it's a faff to get ready, especially compared with the other products we tested.
You need to prepare the solution first, then pour it down the drain. On both occasions when we tested it, the blockage was removed within 30 minutes.
Soda Crystals is an incredibly affordable product with a lot of cleaning utility as you can use it to clean your washing machine, barbeque, pots and pans, as well as stain removal on clothes and fabrics.
Ocado Sink & Drain Unblocker Gel
Our verdict Not the fastest, but by no means less effective
Available from Ocado (£2.25)
Pros
- Clears the pipes
Cons
- Slowly unblocks
- Single-use plastic bottle
Size 500ml
Speed to unblock drain Up to three hours
Suitable for a septic tank Yes
Although it took three hours both times we tested it, this Ocado Sink & Drain Unblocker Gel proved just as effective as most of the others from our test.
HG Kitchen Drain Unblocker
Our verdict Slower than most but effective
Pros
- Clears the pipes
Cons
- Slowly unblocks
- No child safety cap (although it's not required by law to have one)
Size 1 litre
Speed to unblock drain Up to six hours
Suitable for a septic tank Yes
You get more for your money, but this product isn't as simple as just pouring and leaving as you need to mix it with water.
It does take a minimum of six hours to work, but if you're happy to wait or leave overnight, this could be the one for you.
Ecozone Kitchen Drain Unblocker
Our verdict Does the job but slowly
Pros
- Clears the pipes
- Doesn't have too strong a scent
Cons
- Slowly unblocks
- No child safety cap (although it's not required by law to have one)
Size 1 litre
Speed to unblock drain Up to 12 hours
Suitable for a septic tank Yes
During our tests, the Ecozone Kitchen Drain Unblocker did work to remove the clog from our pipes but it took a very long time.
For most people, this won't be an issue if you make sure you do it in the evening before you go to bed.
Tesco Sink & Drain Unblocker
Our verdict A speedy solution to a blocked drain
Available from Tesco (£2.25)
Pros
- Clears the pipes
- Works quickly
Cons
- Single-use plastic bottle
Size 500ml
Speed to unblock drain 15 minutes
Suitable for a septic tank Waiting for a response from the manufacturer
After 15 minutes, the Tesco Sink & Drain Unblocker had done its job and removed the clog from our U-bend.
Buster Kitchen Plughole Unblocker
Our verdict Left behind a new blockage
Pros
- Doesn't leave a lingering scent
Cons
- We needed a plunger to completely remove the blockage
- Single-use plastic bottle
Size 200g
Speed to unblock drain 20 minutes
Suitable for a septic tank Yes
This product did remove the clog, but the mass of the granules created a new blockage we had to force out with a plunger.
In both of our tests, Buster Kitchen Plughole Unblocker dissolved the clogs into a greasy acidic sludge, but the weight and mass of leftover granules fused together to form a new blockage.
However, this second clog was easily flushed away with a single strike of our plunger.
When you use this product don't leave it in the pipes for more than 20 minutes, make sure you wear gloves, don't get any on your skin and open all the windows in the room.
How we test kitchen drain unblockers
We select one drain unblocker per brand, looking at liquid or pouring products widely available in national retailers and purchase all the products we test.
To find out which of our selected drain unblockers is the best, we put the whole selection through the following tests.
We regularly revisit the kitchen drain unblockers on sale to see if there are any more popular products that need testing and when we find them we do.
The setup
- Using a freestanding catering sink, we use one 44mm U-bend per test and stuff it with a clog made from equal parts grated broccoli, melted lard and breadcrumbs.
- To ensure each clog is firmly lodged in place, 500ml of boiling water is poured into the plughole before the test begins.
- The unblockers are then applied following their instructions and left for the minimum required time.
- Afterwards, the U-bends are flushed through with eight litres of hot tap water. If necessary, a plunger is used at this point. We've noted above when a plunger is needed.
The test
- The pipes are examined with a tube camera before and after the products are applied to see how effectively they work.
- Then we time how long it takes for eight litres of cold tap water to pass through the U-bend and pipes.
- We compare these timings to a test done on an unused U-bend. The quicker the water passes through the better and it shows the unblocker has worked. Each product is tested twice.
Why you can trust us: at Which? we're free from manufacturer and retailer influence. Find out more about our impartiality and how your support helps us to stay editorially independent.
How to unblock a kitchen drain
- When working with bleach it's advisable to wear gloves and long sleeve clothing, but make sure it's something that you don't mind risking getting bleach on.
- Pour around 500ml of hot tap water into the drain and allow it time to flow down. If it gets stuck, use a plunger to force it down.
- Then add your kitchen drain unblocker of choice and leave it to work for the recommended time.
- Finally, pour another 500ml of hot water into the drain once the unblocker has had enough time.
Drain unblocker home remedy: bicarbonate soda, salt and vinegar
Did this home remedy get rid of the greasy food residue clogs in our tests? In short, no.
In both attempts, the mixture of bicarbonate soda (125g), salt (125g) and vinegar (125ml) seemed to do nothing but fizz and spit in the plughole.
After waiting 10 minutes, the clog was still firmly in place and so a lot of rigorous plunging action was required to dislodge it.
However, this home remedy is good for regular drain maintenance to prevent major blockages.
How to prevent kitchen drain blockages
Most of the time serious blockages in drains are preventable. Here are some simple steps to help prevent a dreaded blocked sink:
- Scrape plates Make sure you remove food residue from your plates, bowls and utensils before you put them in the sink.
- Drain protector Get a drain protector to catch stray bits of food residue before they disappear down the plughole.
- Enzyme cleaning sticks Dropping an enzyme cleaning stick down the plughole once a month is a good way to prevent germs, odours and blockages.
- No coffee grounds in the sink Throw away your coffee grounds in your food waste, compost or bin.
- Collect the fat Collect fat and grease from cooking in a disposable container (juice or milk carton or another non-recyclable container) before putting it in with your general waste.
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What are the chemical hazard symbols and what do they mean?
Many drain unblockers contain chemicals that are hazardous to us and the environment.
Below you can see the symbols found on some products, what they mean and the safety advice for handling them.
| Chemical hazard symbols and what they mean | |
 | Explosive (symbol: exploding bomb) |
A substance that under defined test conditions when dry or under the effect of flame or heat may explode.
| |
 | Flammable (symbol: flame) |
Flammable if exposed to ignition sources, sparks or heat. Some substances with this symbol may give off flammable gases in contact with water.
| |
 | Oxidising (symbol: flame over circle) |
May cause explosion, fire or damage to living tissue resulting in chemical burns. Reacts with other substances to produce a highly exothermic reaction.
| |
 | Corrosive (symbol: corrosion) |