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Best drain unblocker: Unclog your sinks with the best chemical and enzyme-based unblockers

Jane Hoskyn
28 Sep 2021
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Shower, bath and kitchen sink clogged to a standstill? Get those plugholes flowing fast again with the best drain unblockers

It doesn't take long for hair, food waste, soap scum and a dollop of unidentifiable household gunk to clog up your plugholes. The best drain unblockers can go where no plunger or kettle of boiling water can, dissolving and even digesting the clogs without damaging you, your sink or your plumbing.

Drain unblockers are surprisingly varied products. Some are designed specially to tackle bath and shower wastes clogged to a standstill with hair and grease, while others use gentler enzyme-based formulas to eat away mould and grime from outdoor drains and waste disposal units. The best unblockers cling to the walls of your pipes and keep them flowing freely for months to come.

Skip down the page to discover our top recommended drain unblockers to free various pipes around your home, or read on for more tips on choosing the right unblocker for the job.


Best drain unblocker: At a glance

  • Best all round: Mr Muscle Mx Gel | Buy now
  • Best for baths and showers: Buster Bathroom Plughole Unblocker | Buy now
  • Best enzyme-based organic unblocker: HG Kitchen Drain Unblocker | Buy now
  • Strongest drain unblocker: Instant Power Hair & Grease Drain Opener| Buy now
  • Best for outdoor drains: Jeyes Drain Unblocker Heavy Duty | Buy now
  • Best for toilets and waste disposals: Instant Power Slow Drain | Buy now

    How to choose the best drain unblocker for your home

    Does it really matter which drain unblocker I buy?

    Most chemical drain unblockers are based on caustic soda (sodium hydroxide), which eats through blockages without damaging pipes. But caustic soda is not the right choice for all blockages and could be dangerous if used on a toilet, waste disposal or any other unit that's likely to overflow when blocked. So to clear clogs effectively and safely, choose the right one for the job.

    Solid blockages in your kitchen and bathroom pipes, including shower wastes and kitchen sinks, are best cleared using chemical-based drain unblockers. Their caustic ingredients produce gaseous heat that dissolves blockages including congealed fat, soap-scummy hair, and even limescale.

    For best results, try loosening the blockage with a plunger and hot water first. Never use a plunger after pouring a chemical unblocker!

    Pipes and drains that aren't fully blocked can be tackled using enzyme-based drain unblockers, which are gentler than chemical unblockers. They contain bacteria cultures and concentrated enzymes that effectively digest organic substances such as food and mould, and will continue working long-term to prevent further build-up.

    The main disadvantage of enzymatic unblockers is that they won't eat through solid blockages. They need to be able to flow through the pipe to get the job done. So if you want to avoid chemical unblockers, loosen blockages using a plunger and boiling water before you go in with an enzyme-based unblocker.

    Toilets and waste disposals should only be tackled using plungers and enzyme-based drain unblockers, never with caustic soda products.

    Will a drain unblocker damage my pipes and sink?

    Stainless steel sinks and plugholes can be corroded by chemical unblockers, so take care when pouring.

    All our recommended products are in liquid or gel format. Not only are they easier and safer to control than powder or granular products, but they also work more effectively because they cling to pipes to ensure everything is cleared. Powder unblockers can form clumps, causing corrosion and making blockages worse. They can also be breathed in, so if you must use them, wear a mask and goggles.

    PVC pipes are now standard for drainage in the home, including shower and kitchen sink waste traps. All the chemical and enzymatic unblockers we recommend say they're safe to use on all pipes, including PVC. However, some damage is hard to avoid if you use the product a lot over an extended time. Enzyme-based unblockers cause less damage in the long term but remember they only work if the pipe isn't fully clogged in the first place.

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    The best drain unblockers you can buy now

    1. Mr Muscle Max Gel: Best all-around drain unblocker

    Price: £9.70 | Buy now from Amazon

    Popularity isn't always a sign of quality, but market leader Mr Muscle really is the best of the bunch. It combines bleach and caustic soda (sodium hypochlorite and sodium hydroxide) to dissolve most types of blockage in five to 30 minutes and blitz unwanted odours to boot. A single dose is usually enough to clear gunk including hair and greasy food build-up, but you're safe to give it another go if necessary, or leave it overnight before flushing with hot water.

    The thick consistency of Max Gel means you're unlikely to suffer splashes on your skin (although it's always worth wearing gloves and a mask when using these products), and it's heavy enough to sink through standing water to reach the gunk. And unlike some well-known chemical unblockers we've tried (none we've recommended), Mr Muscle doesn't corrode stainless steel. In fact, a little of this stuff wiped around the sink and plughole now and then is great for keeping things shiny. You'll need to rinse it thoroughly, though, and put up with a slight bleachy whiff.

    Key details – Size: 2 x 1L; Type: Chemical; Format: Gel


    2. Buster Bathroom Plughole Unblocker: Best drain unblocker for hair-clogged baths and showers

    Price: £2.30 | Buy now from Amazon

    You don't see Amazon reviews much more positive than those for Buster Bathroom Plughole Unblocker. There are hundreds of five-star reviews from verified buyers who've spent years pulling sludge from slow-draining showers and plugholes – and even dismantling wastes regularly to remove human hairballs – only to find that Buster does the job faster, without corroding pipes or sinks.

    This relatively small 300ml 'one-shot' bottle is enough to get a clogged pipe flowing freely again. As with all these products, leaving it overnight before a thorough rinse with hot water produces the best results, but buyers report that Buster can get a fully-clogged shower waste pipe flowing freely in less than an hour. It also lacks the bleachy smell of Mr Muscle, making it more pleasant for the bathroom.

    Key details – Size: 300ml; Type: Chemical; Format: Liquid


    3. HG Kitchen Drain Unblocker: Best enzyme-based drain unblocker

    Price: £5 | Buy now from Amazon

    This affordable, biodegradable liquid unblocker from Dutch cleaning specialist HG uses enzymes and microbes to tackle grease and food particles in the waste pipes under your kitchen sink and keep those plugholes emptying fast. It's not quite strong enough to eat through solid blockages (you'll need a plunger, plumber or chemical unblocker for that), but it's brilliant for cleaning gunky pipes before they can get fully clogged, and for keeping the kitchen smelling clean. And its enzyme-based formula means it's safer to keep around the house and use on pipes long-term, although it should still be kept out of reach of kids and pets.

    Key details – Size: 1L; Type: Enzymatic; Format: Liquid


    4. Instant Power Hair & Grease Drain Opener: Strongest drain unblocker to remove stubborn blockages

    Price: £8.70 | Buy now from Amazon

    Big red capital letters on a black bottle – this stuff means business, right? Very much so. This drain unblocker from Texas-based chemical company Scotch Corporation claims to be the strongest formulation on the market. It also claims to be safe for 'all' types of pipe, but the label carries the disarming instruction: 'Wear safety goggles to protect from possible eruption of Lye'. That's caustic soda to you and me.

    The thin liquid consistency makes splashes a real risk, so take extremely good care when using this stuff. The strong chemical formula melts away all kinds of blockage, including solidified grease and oil, although you may need to leave it overnight to tackle large blockages. And like other chemical unblockers, it's not safe to use in toilets or waste disposals.

    Key details – Size: 1L; Type: Chemical; Format: Liquid


    5. Jeyes Drain Unblocker Heavy Duty: Best unblocker for outdoor drains

    Price: £8 | Buy now from Amazon

    Specially formulated for use outdoors, this thick liquid from Jeyes is strong enough to open fully blocked outdoor drains that have been clogged to a standstill with leaves and household waste. It deodorises while it works, leaving drains smelling pleasantly fresh, and the clingy consistency means it keeps drains unblocked for weeks on end.

    Despite its outdoor-friendliness, it's still a caustic chemical formula, so be wary of using Jeyes in places where it might be accessed by pets and wildlife, and flush with hot water when the blockage has cleared.

    Key details – Size: 1L; Type: Chemical; Format: Liquid


    6. Instant Power Slow Drain Build-Up Remover: Best enzyme-based drain unblocker for toilets and waste disposals

    Price: £10.30 | Buy now from Amazon

    Unlike chemical-based drain unblockers, Instant Power Slow Drain is safe to use in blocked toilets, waste disposals and septic tanks, as well as other drains around the home. So if your loo or even your washing machine isn't emptying as fast as it should, this is the product to use, rather than anything containing caustic soda. It won't work on solid blockages, but it's environmentally friendly enough to be used daily, so you could put a couple of capfuls down the sink each night to keep things flowing and stink-free.

    Key details – Size: 1L; Type: Enzymatic; Format: Liquid

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