The Best Drain Unblockers For All Types Of Blockages
Gels and liquids that clear a slow sink or a flooding shower tray without calling a plumber.
Our quick verdict
Our pick of the best drain unblocker is the Mr Muscle Max Drain Gel. It cleared hair and general gunge every time we tested it, with nothing more than a five minute wait and a hot water flush. For outside gullies, the Jeyes Drain Unblocker is the better bet, and it gave us the best result when we left it in overnight.
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Our Picks At A Glance
- Check price of Mr Muscle Max Drain Gel
- Check price of Buster Bathroom Plughole Unblocker
Best For Hair
Buster Bathroom Plughole UnblockerShowers, baths and basins clogged with hair and soap scum
- Check price of HG Liquid Drain Unblocker
- Check price of Scotch Corporation Instant Power
Best Heavy Duty
Scotch Corporation Instant PowerFully blocked drains where gentler formulas have failed
- Check price of Jeyes Drain Unblocker
- Check price of Spear & Jackson Heavy Duty Sink and Drain Unblocker
Most Versatile
Spear & Jackson Heavy Duty Sink and Drain UnblockerHouseholds that want one unblocker for indoor and outdoor drains
What's causing the blockage decides the bottle. Hair and soap scum in a shower need a different formula from fat in a kitchen sink, and leaves and silt in an outside gully need something that clings. Standing water is the other clue, since a heavy gel sinks down to the clog while a thin liquid suits a plughole that's just slow.
Blocked drains are a regular call-out across the rentals and Airbnbs we look after. The six formulas below cover hair, grease and outside drains, plus a caustic option for when nothing else shifts it.
How We Tested These Drain Unblockers
Every kind of blockage turns up across our properties. Bathroom basins and showers clog with hair, kitchen sinks with fat and food, and outside drains with whatever washes into them. Most of the time a decent unblocker clears the job without us having to take the pipework apart, and that's how we've built up our view of which formulas work.
When we test a formula, we follow the dose and waiting time on the label and then flush with hot water. We judged them on four things:
- How well the blockage cleared
- How easy the formula was to pour and dose
- How long it needed to get to work
- Whether it left the plughole smelling fresher or worse
Our YouTube Short on this page shows an HG sink unblocker working on a blocked bathroom basin. You can see the formula doing its job, and it's a satisfying one to watch. For the formulas we've had less use out of, we've leaned on the brand's own guidance for dose and waiting time and said so in the write-up.
Watch Our Test
How Satisfying Is This Sink Unblocking! We've Tested The Latest Sink Unblockers To Find The Best!
The Best Drain Unblockers We Recommend
Read the label before you pour, as the dose and waiting time differ a lot between these formulas. Never mix two drain unblockers in the same pipe.
Best Overall
Mr Muscle Max Drain Gel
Best for: Slow-running kitchen and bathroom plugholes
Check Price On AmazonMr Muscle aims Max Drain Gel squarely at slow-running kitchen and bathroom plugholes, and that everyday blockage is where it earns its place as our top pick.
The method is straightforward. Pour in the dose shown on the bottle, leave it for up to five minutes, then run hot water from the tap to flush it through. It's dealt with hair and general gunge every time we've tested it, though the more stubborn blockages needed a bit of agitation after the gel had softened them. If the first dose doesn't shift it, Mr Muscle recommends using a second dose and leaving it overnight before flushing.
What we like
- Proved effective every time in our testing
- Works on kitchen and bathroom plugholes
- Breaks down hair and gunge
- Gets to work in around five minutes
What to know
- Tough blockages needed some agitation as well as the gel
Our verdict
Speed is what wins it for Mr Muscle Max Drain Gel. Five minutes and a flush of hot water from the tap clears most slow sinks and basins, and a quick poke with a brush handles the stubborn ones. Keep a bottle in the cupboard and most plughole blockages never get as far as a plunger.
Best For Hair
Buster Bathroom Plughole Unblocker
Best for: Showers, baths and basins clogged with hair and soap scum
Check Price On AmazonBuster has split its plughole range by room, and the Bathroom version is made for the hair and soap scum that block showers, baths and basins. That focus is what makes it so effective in a bathroom, where a matted ball of hair sits in the trap and catches everything that follows. It's the same soap scum that dulls your screen, and our guide to cleaning shower glass without streaks deals with that side of it.
Pour the full 300ml bottle down the plughole, leave it for up to 15 minutes, or overnight for a bad blockage, then flush it with hot water. It's worked well for us in testing, and it's made in the UK. Kitchen fat is a different job, so Buster makes a separate Kitchen Plughole Unblocker for it, and that's the bottle you can see over a kitchen sink in our testing photo.
What we like
- Made specifically for hair and soap scum
- Gets to work in up to 15 minutes
- Suits baths, showers and basins
- Single 300ml dose with nothing to measure
- Made in the UK
What to know
- Not for kitchen sinks, which need Buster's Kitchen version
- Each bottle is one dose, so keep a spare for repeat blockages
Our verdict
Hair is the problem this formula solves best, and it cleared the bathroom blockages we tried it on during testing. The full bottle goes in at once, so there's nothing to measure. It's no good on kitchen fat, so a household with a slow kitchen sink as well should pick up Buster's Kitchen formula or Mr Muscle Max Drain Gel alongside it.
Best All-Rounder
HG Liquid Drain Unblocker
Best for: Light to medium blockages and smelly drains in any room
Check Price On AmazonHG's liquid is ready to use from the bottle and suitable for every type of waste pipe, so it's the one to keep if you only want a single unblocker in the house. It's designed not to foam as you pour it, which stops it bubbling back up out of a full sink.
In testing we poured about half the bottle down the plughole, left it for up to 30 minutes and then flushed it away, and our YouTube Short shows an HG unblocker working on a bathroom basin. It did a great job of getting rid of the stale smell that comes up from a slow drain. Where it fell short was on solid blockages, as it's at its best on light to medium clogs, so for a pipe that's properly blocked a stronger formula or a plunger is the better bet.
What we like
- Suitable for every type of waste pipe
- Non-foaming formula pours cleanly
- Clears blockages within 30 minutes
- Got rid of drain odours well in our testing
- Half a bottle per use in our testing, so one bottle covers two jobs
What to know
- Only effective on light to medium blockages in our testing
Our verdict
HG Liquid Drain Unblocker is a good all-round choice for slow drains and bad smells in any room, and the half-bottle dose makes it fair value. It isn't the one for a fully blocked pipe, where the Scotch Corporation Instant Power has more strength. Hair-clogged showers respond better to the Buster Bathroom formula.
Best Heavy Duty
Scotch Corporation Instant Power
Best for: Fully blocked drains where gentler formulas have failed
Check Price On AmazonWhen the water isn't moving at all, you need something with more bite. Scotch Corporation describes Instant Power as its strongest formula, and it contains concentrated lye, which creates heat as it works to melt grease and dissolve hair.
The brand says to pour 2 to 4 cups into the plughole, leave it for an hour and then flush with hot water, and it states the formula is safe for all household piping. Because it's so concentrated, treat it with respect. Wear rubber gloves and eye protection, keep the room ventilated and never use it after another drain cleaner is already in the pipe, as mixing chemicals can react violently. This is a formula for serious blockages, not for routine use.
What we like
- Concentrated lye formula for stubborn blockages
- Generates heat that melts kitchen grease
- Dissolves thick hair clogs
- Safe for all piping according to Scotch Corporation
What to know
- The most expensive formula in our roundup
- Needs gloves and eye protection because it's so caustic
Our verdict
Scotch Corporation Instant Power makes the most sense for a drain that's completely blocked and hasn't responded to anything else. It costs the most here and needs careful handling, so for everyday slow plugholes, Mr Muscle Max Drain Gel is the easier and cheaper option.
Best Outdoor
Jeyes Drain Unblocker
Best for: Outside gullies and drains blocked by leaves, grease and food
Check Price On AmazonOutside drains collect a different mix of debris from the ones indoors, and Jeyes has made this unblocker for that job. The brand says it's tough on grease, hair, soap scum, food and decaying leaves, which covers most of what ends up in a gully under a kitchen waste pipe or a downpipe.
The clinging formula is ready to use from the bottle, and Jeyes quotes 30 minutes for it to get to work. It also cleans and deodorises the drain, which helps with the smell that comes off a blocked gully in summer. When we tested it, we left it in overnight and flushed the drain through with hot water in the morning, and that cleared the blockage well.
What we like
- Unblocks, cleans and deodorises in one
- Gets to work in 30 minutes according to Jeyes
- Ready to use straight from the bottle
- Clinging formula stays on the blockage
- Cleared our outside drain when left overnight
What to know
- Made for outside drains, so it isn't our pick for sinks and basins
Our verdict
For outside drains and gullies, Jeyes Drain Unblocker is our choice, and it's good value for the job. Leave it in overnight, as that's how it gave us the best result. If you want one product for inside and outside drains, the Spear & Jackson unblocker covers both, and for indoor plugholes, Mr Muscle Max Drain Gel is the better fit.
Most Versatile
Spear & Jackson Heavy Duty Sink and Drain Unblocker
Best for: Households that want one unblocker for indoor and outdoor drains
Check Price On AmazonSpear & Jackson is best known for garden tools, but it also makes a range of liquid treatments, including this heavy-duty sink and drain unblocker. The brand says it clears fat, soap scum, hair and other deposits in both interior and exterior drains, so you can use the same bottle on a kitchen sink and an outside gully.
It's described as fast acting, and Spear & Jackson suggests using it regularly to keep drains running freely rather than waiting for a full blockage. It leaves a fresh smell behind. You can buy it as a 500ml bottle for the odd job or a 5 litre container if you look after several properties or a long run of outside drains.
What we like
- Works on indoor and outdoor drains
- Fast-acting heavy-duty formula
- Can be used regularly to keep drains running freely
- Leaves a fresh smell
- Sold in 500ml and 5 litre sizes
What to know
- Costs more than the Jeyes formula for outside drains
Our verdict
The Spear & Jackson unblocker suits anyone who wants a single product for sinks, showers and outside drains, and the 5 litre size makes sense for landlords. If you only need to clear an outside drain, the Jeyes formula costs less, and for hair in a shower, the Buster Bathroom Plughole Unblocker is more targeted.
Choosing The Right Drain Unblocker
The best drain unblocker for your home depends on what's causing the blockage and where it is. Picking a formula made for that job saves wasted bottles and repeat attempts.
Match The Formula To The Blockage
Bathroom blockages are almost always hair bound together with soap scum, and formulas such as Buster Bathroom are made to break that down. Kitchen sinks clog with fat and food, which need a formula that cuts through grease. Outside drains collect leaves, silt and whatever has washed off the patio, and a clinging formula such as Jeyes works best there. All-rounders such as HG and Spear & Jackson cover several jobs but won't always match a specialist on its own ground.
Gel Or Liquid Formula
Thick gels are heavier than water, so they sink through a full sink or shower tray to reach the blockage. Thinner liquids work well when the water has drained away and the clog is just slowing things down. If water is standing in the basin, bail out what you can and choose a gel.
Waiting Time And Dosing
Waiting times vary a lot between these formulas, from a few minutes for Mr Muscle up to an hour for Scotch Corporation Instant Power, and some work best left overnight. Follow the label, as pouring hot water in too early just washes the formula away before it's done its job. Check how much each use needs too, because a bottle that does two jobs is cheaper than it looks.
Handling Caustic Drain Cleaners Safely
Strong drain unblockers are caustic, so wear rubber gloves and keep them away from your eyes and skin. Open a window while they work. Never mix two different products in the same drain or use a plunger straight after pouring, as either can splash concentrated chemical back at you. Check the label says it's safe for your pipes, especially in older homes with metal pipework.
When A Chemical Won't Clear It
If two doses haven't helped, the blockage is either solid or further down the pipe than the formula can reach. Take the trap off under the sink and clear it by hand, use a plunger or drain snake, or rod the outside drain. Some pressure washers for outdoor cleaning take a drain cleaning hose too, which blasts through silt in an outside run. A gully that keeps blocking may be filling with silt from the patio, and our guide to cleaning patio slabs covers how to stop washing debris straight into it. Blockages that keep coming back can point to a collapsed or root-damaged pipe, which needs a drainage engineer and a camera survey.
Blocked Drain Questions From Our Readers
Are drain unblockers safe for plastic pipes?
Most drain unblockers sold in the UK are safe for plastic waste pipes when you follow the dose and waiting time on the label. Check the bottle before you buy, as some heavy-duty caustic formulas carry warnings about certain pipe materials. Don't follow a strong unblocker with boiling water in a plastic pipe, as very hot water can soften joints over time.
Can you use drain unblocker in a toilet?
Only use a drain unblocker in a toilet if the label says it's suitable. Toilet blockages are made of paper and waste rather than hair or grease, so most plughole formulas won't shift them. A toilet plunger is the first thing to try, followed by a toilet auger. If several toilets and drains are slow at once, the blockage is in the main drain outside.
What should you do if drain unblocker doesn't work?
If a drain unblocker doesn't work after a second dose, clear the blockage by hand. Put a bucket under the sink, unscrew the trap and pull out the debris, or use a plunger or drain snake on the plughole. Outside drains can be cleared with drain rods. A blockage that keeps returning needs a drainage engineer to check the pipe.
How do you stop drains blocking again?
The best way to stop drains blocking again is to keep hair, fat and food out of them. Fit a hair catcher in the shower and bath plughole, wipe greasy pans with kitchen roll before washing them and use a sink strainer in the kitchen. A monthly dose of a maintenance formula such as Spear & Jackson helps keep the pipes running freely.
Which unblocker would you use for a shower clogged with hair?
Buster Bathroom Plughole Unblocker is the one we'd use, as it's made for exactly that mix of hair and soap scum. Pour in the full 300ml bottle, leave it for up to 15 minutes, or overnight for a bad blockage, then flush with hot water. It cleared the bathroom blockages we tried it on.
Is Scotch Corporation Instant Power worth paying more for than Mr Muscle Max Drain Gel?
Only for a drain that's completely blocked and hasn't responded to anything else. Scotch Corporation Instant Power costs the most in our roundup and is caustic enough to need gloves and eye protection. A slow plughole doesn't need that much strength, and Mr Muscle Max Drain Gel is cheaper, easier to handle and gets to work in around five minutes.
Can one bottle of unblocker handle both my sink and my outside drain?
Spear & Jackson Heavy Duty Sink and Drain Unblocker is the one made for both, as the brand says it clears fat, soap scum, hair and other deposits in indoor and outdoor drains. It's sold in 500ml and 5 litre sizes. If you only need to clear an outside drain, the Jeyes formula costs less.
Should I leave drain unblocker in overnight?
Leave it overnight only where the label allows it. Buster Bathroom suits an overnight soak for a bad blockage, and Mr Muscle recommends a second dose left overnight if the first doesn't shift it. We left Jeyes in overnight and flushed with hot water the next morning, which cleared our outside drain. Never mix two products in the same pipe.
The Drain Unblockers We'd Keep Under The Sink
For most slow kitchen and bathroom plugholes, Mr Muscle Max Drain Gel is the one to buy, as it gets to work in minutes. For hair-clogged showers and baths, the Buster Bathroom Plughole Unblocker is the better choice, and Jeyes Drain Unblocker is the one for outside drains.
Keep the Scotch Corporation Instant Power for blockages nothing else will shift, and handle it carefully. After clearing a bathroom drain, our guide to cleaning a limescaled shower head is a good next job while the tools are out.
Richard has spent years renovating properties and turning them into rentals and Airbnbs. Like a lot of people he started out as a beginner, and these days there isn't much DIY he won't take on.