The old remedy that enrages half the internet: no vinegar no baking soda just a half glass trick that claims to clean any drain by itself and leaves plumbers and grandmothers furiously divided

Harriet Pemberton • April 28, 2026 02:18

It starts like a painfully familiar Saturday-morning scene: joggers on, coffee in hand, and that dull, ominous gurgle from the kitchen sink you’ve been pretending not to hear all week. You turn the tap. The water rises-slowly-and you know what’s coming. Your drain has had enough.

So you do what everyone does: you panic-Google “blocked drain home remedy”. Between vinegar, bicarbonate of soda and nuclear-strength chemicals, one bizarre tip suddenly pops up: “No vinegar, no bicarb - just a half-glass trick that cleans any drain by itself.”

Half a glass. Nothing else.

And that so-called miracle tip has been dividing the internet for months. Grandmothers argue with plumbers, TikTok clashes with trade forums-and somewhere in the middle stands the rest of us, staring at a gurgling U-bend (trap) and wondering what to believe.

The half-glass trick for blocked drains that has the whole internet rattled

The same story plays out in thousands of homes: a sluggish bath that drains like treacle, washing-up water pooling in the kitchen, foam sitting stubbornly in the basin. Then someone breezes in with effortless confidence and says: “All you need is half a glass.”

No drain cleaner, no plunger, no special tools. Just one glass-half full-either poured down the plughole or placed “over” it depending on the version, and supposedly the rest happens “by itself”.

We all recognise that brief flicker of hope when a simple hack promises an easier life-especially when it sounds less miserable than an evening of dismantling the trap.

What keeps the debate going is that the half-glass trick shows up in several competing versions:

Half a glass of table salt, poured into the drain and left overnight.
Half a glass of washing-up liquid, followed by hot water.
The “mysterious” version: “Half a glass, then boiling water-my gran always did it,” without ever admitting what’s actually in the glass.

It’s great for clicks and awful for clarity. Under the same clip you’ll see “Worked perfectly, thank you!” right above “My drain is completely blocked now-cheers.” A few seconds of scrolling and it’s obvious: what should be a mundane household fix has turned into a full-blown argument.

What’s really in the “half glass”?

Once you strip away the hype, the discussion usually boils down to three candidates: washing-up liquid, salt, or cooking oil-the most common “secrets” that people eventually admit to in forums.

The logic sounds plausible at first glance:

Washing-up liquid is meant to break down grease.
Salt is supposed to scrub slightly and draw out moisture.
Oil is claimed to create a slippery film that helps deposits shift.

The catch is that drains rarely block for just one reason. Most clogs are a stubborn mash-up of hair, soap scum, grease, food scraps and limescale, forming a compacted mat. Half a glass of anything tends to tackle only one slice of the problem-sometimes that’s enough, and sometimes it isn’t.

When the half-glass trick can help (and when it won’t)

There are situations where the gentler forms of the half-glass trick can genuinely make a difference.

If a kitchen sink is running slow-but not fully blocked-half a glass of washing-up liquid, chased with very hot water, can loosen soft grease build-up before it hardens into something more stubborn. Used occasionally, it can function as a sort of mini-maintenance step, especially if you cook with oils, fats and rich sauces.

A modest amount of salt can also be mildly abrasive on light, slimy films; with hot water it may help shift some surface residue.

And let’s be realistic: almost nobody dismantles their U-bend every other day and cleans it meticulously. That’s exactly why a quick, low-effort trick is tempting-particularly after work, when you want the sofa, not a plumbing session.

Where it fails is equally predictable. If the drain has been barely moving for weeks or months, the build-up is usually too compacted for a half-glass “hack” to break through on its own.

The classic mistake: “If half a glass helps, three will be amazing”

This is where things often go wrong. People escalate: if half a glass is good, then surely two or three must be better. That’s how you end up pouring so much product down the plughole that the effect flips.

Too much washing-up liquid can create thick foam inside the pipe that traps grime rather than shifting it.
Too much salt can settle in sluggish sections where it doesn’t rinse away properly.
Oil can bind with fats and, in cooler pipework, form a sticky, greasy coating that makes blockages worse.

At that point the drain isn’t just slow-it can become fully blocked.

That’s when curiosity turns into genuine panic.

“I love home remedies, but I love unblocked pipes more,” one viewer wrote under a viral clip. “My gran would have finished me off if I’d poured cooking oil down the sink, no matter what TikTok says.”

Plumbers tend to agree with the sentiment. They’re not automatically anti–home remedy; they’ve simply seen what happens when trends are copied without context.

A practical way to use the half-glass trick without making things worse

If you want the calm, non-dramatic version-the one that’s least likely to backfire-these guidelines are the safest place to start:

Use the half-glass trick only when the drain is slow, not when it’s completely blocked.
Stick to the most benign option: half a glass of washing-up liquid, followed by very hot water.
Avoid oil in the drain entirely, however convincing the “slippery film” claim sounds.
Use salt sparingly, and only if plenty of water can flush through afterwards.
If water is standing and not draining at all: stop experimenting and call a professional.

Two extra realities viral clips rarely mention

First: your plumbing setup matters. In some homes, especially where pipework is older, poorly vented, or already narrowed by limescale, even “gentle” tricks can behave unpredictably. If you notice gurgling from other plugholes, recurring smells, or multiple slow drains at once, the problem may be deeper in the system than the sink trap-and that’s not a half-glass job.

Second: there’s a difference between maintenance and repair. A simple routine (strainers, occasional hot flushes, cleaning the trap) prevents many clogs from forming; once a blockage is established, mechanical methods-like a plunger or a proper drain snake-are often more reliable than pouring more substances down the pipe.

Why the half-glass debate feels bigger than it should

The frenzy around half a glass is also a neat snapshot of modern life. We crave quick fixes with minimal effort-ideally “natural”, ideally the way “gran used to do it”. At the same time, we live with modern pipework, dishwashers, shampoos and shower gels our grandparents never had.

Those worlds don’t always line up.

Maybe the most interesting question isn’t whether salt or washing-up liquid sometimes works, but how we handle online promises. Do we share every hack because it sounds dramatic? Do we trust anonymous accounts over the person who unblocks drains for a living? And honestly-when did you last look at your U-bend on purpose, rather than only when it was already too late?

Key points at a glance

Key point	Detail	Added value for the reader
Half a glass as a “miracle trick”	Usually means washing-up liquid, salt or oil combined with hot water	Makes the vague online hype concrete and understandable
Limits of home remedies	Minor slow drains: sometimes. Fully blocked pipes: usually not.	Helps you judge when a hack is acceptable and when it’s risky
A practical household approach	Regular prevention, cautious use of the trick, calling a professional in time	Gives clear steps you can apply immediately at home

FAQ

What does “half a glass” actually mean?
Most often it refers to half a glass of washing-up liquid or salt put down the drain and then flushed with hot water. Many viral posts stay deliberately vague to build suspense, which is why people end up confused.
Can the half-glass trick damage my pipes?
In sensible amounts, washing-up liquid is generally low-risk, and salt in modest doses is usually fine too. Problems arise when people overdo it, when pipework is older or already compromised, or when oil is recommended-because that can create sticky build-up that becomes expensive later.
Why do so many plumbers dislike these home remedies?
Because they deal with the aftermath: situations where well-meant experiments turned into real plumbing disasters. Most aren’t against home remedies in principle-they’re wary of one-size-fits-all advice and trend-driven misuse.
What should I do regularly instead?
Use a plughole strainer, remove hair and food scraps consistently, clean the U-bend (trap) roughly once a month, and run hot water through occasionally. It’s not exciting, but it works quietly in the background. In the long run, prevention is often cheaper than any hack.
How do I know I should call a professional straight away?
If the water won’t drain at all, there’s a strong smell, you hear gurgling coming from other drains, or several plugholes have problems at the same time. That’s when the “miracle trick” phase is over and damage control begins.