A blocked sink or bath drain usually clears with three household staples and about 15 minutes of patience, no bleach or drain-unclogging gel required.
TL;DR
Bicarbonate of soda, white vinegar and boiling water clear most kitchen and bathroom drain blockages in under 20 minutes, and this is the safest first move before reaching for a chemical drain cleaner. For grease-heavy kitchen sinks, a drain snake or plunger paired with the vinegar-and-bicarb method works even better. Verdict: try the natural method first in 2026 — it's cheaper, safer for old pipes, and solves roughly 80% of household clogs on its own.
Why this matters
Chemical drain cleaners are corrosive, and repeated use eats away at pipe seals, especially in older UK homes with cast iron or ageing PVC. They're also nasty to store around kids and pets. Most household clogs are made of soap scum, hair, food grease and limescale, all of which respond to heat, acid and abrasion rather than industrial chemicals. Natural unblocking also means you're not pouring caustic soda into wastewater that eventually reaches rivers and treatment plants. If you're already trying to cut plastic and chemicals out of your cleaning cupboard, this is the drain method that fits that habit.
What you'll need
- 1 kettle of boiling water
- 4-6 tablespoons of bicarbonate of soda
- 200ml white vinegar
- An old cloth or rag to plug the overflow hole
- A sink plunger (cup type for flat drains, flange type for toilets)
- A drain snake or straightened wire coat hanger
- Rubber gloves for anything that involves reaching into the trap — reusable natural latex gloves hold up better against grease and grit than thin disposable ones
- A bucket to catch water from the U-bend
If the blockage is in a kitchen sink, keep a bottle of natural bleach nearby for a final rinse once the clog clears — it lifts grease residue without the fumes of a standard bleach product.
The steps
1. Clear standing water first
Bail out or scoop any standing water in the sink or bath before you start; a dry drain lets boiling water and vinegar hit the blockage directly instead of diluting into a pool. Use a cup or small jug and don't skip this — pouring hot liquid into standing cold water cuts its unclogging power fast.
Common mistake: pouring boiling water straight down a fully blocked sink, which just backs up and overflows onto the counter.
2. Pour boiling water down first
Boil a full kettle and pour it down the drain in two stages, waiting 30 seconds between pours. Heat alone melts soap scum and loosens grease that's clinging to pipe walls, and this step alone clears a surprising number of slow-draining sinks in 2026 without needing anything else.
Common mistake: using boiling water on PVC pipes that already show signs of stress or on a fully sealed toilet bowl blockage, where the water just sits without pressure to push it through.
3. Add bicarbonate of soda
Tip 4-6 tablespoons of bicarbonate of soda directly into the plughole and let it sit for 5 minutes untouched. Bicarb is mildly abrasive and alkaline, which helps break down the outer layer of grease and soap buildup before the acid stage does the rest.
Expected outcome: you'll often hear a faint fizzing start even before the vinegar goes in, especially in bathroom drains with soap residue.
4. Follow with white vinegar
Pour 200ml of white vinegar down the same drain and immediately cover the plughole with a cloth or plug. The bicarb-vinegar reaction produces carbon dioxide, and trapping that gas forces pressure into the blockage instead of letting it escape upward, which is what actually pushes debris loose.
Common mistake: leaving the drain open during this step — the fizzing looks satisfying but the pressure just vents out uselessly.
5. Wait, then flush with more boiling water
Leave the mixture to work for 10-15 minutes, then remove the cloth and pour another full kettle of boiling water through. This second flush clears the loosened grease and mineral deposits out of the pipe entirely rather than just repositioning them further down.
Expected outcome: water should now drain at normal speed. If it's still slow, repeat steps 3-5 once before moving to mechanical methods.
6. Plunge if water still isn't moving
If the drain is still sluggish after two vinegar-bicarb rounds, add a few centimetres of water to the sink or bath and use a cup plunger, sealing the overflow hole with a wet cloth first so pressure doesn't just escape there. Plunge firmly 10-15 times in short, sharp strokes rather than slow pushes.
Common mistake: plunging without sealing the overflow hole — you lose most of the suction and the clog barely moves.
7. Use a drain snake for stubborn hair and debris clogs
For bathroom sinks and baths, hair-and-soap clogs sitting just past the trap often need mechanical removal. Feed a drain snake or a straightened wire coat hanger with a small hook bent into the end down the plughole, twist gently, and pull out whatever surfaces — expect this to be unpleasant but effective.
Common mistake: pushing the snake in too fast and packing the clog tighter instead of hooking it.
8. Rinse and reset with a final clean
Once water drains freely, run the hot tap for two minutes and finish with a splash of natural bleach or a wipe-down of the sink area to clear residue and smell. This is also the moment to give the surrounding surfaces a proper clean while you're already set up.
Troubleshooting
- Water drains but slowly, even after two rounds: the blockage is likely further down the pipe than bicarb and vinegar can reach — try the drain snake before considering a plumber.
- Bad smell persists after the drain clears: run bicarbonate of soda alone (no vinegar) followed by hot water once a week for a month; lingering odour usually means residual grease film, not a new clog.
- Toilet won't clear with the vinegar method: toilets need mechanical force, not chemistry — go straight to a flange plunger, and if that fails within 10 minutes, stop and call a plumber rather than risk overflow.
- Bathtub drains slower than the sink: hair buildup around the stopper mechanism is the usual culprit; unscrew or lift the stopper and clear hair manually before trying any liquid method.
- Kitchen sink clogs again within a week: grease is solidifying in the pipe past your reach; pour boiling water down after every wash-up for a week and avoid pouring fat or oil down the drain at all.
- Outdoor drain or gully is blocked: natural methods work less well outdoors because rainwater dilutes them fast; clear visible debris by hand first, then treat the same as an indoor drain.
Tools and resources
- Rubber gloves for any manual clearing work: reusable natural latex gloves
- A bottle of grease-cutting cleaner for the finishing wipe-down: natural bleach
- A general-purpose spray for the surrounding sink and taps once the drain's clear: multi-surface cleaner
- Bicarbonate of soda and white vinegar, both available from any UK supermarket
- A basic drain snake, sold cheaply at most hardware shops
What to do next
If your drains clog repeatedly because of hard water limescale rather than grease or hair, the natural bicarb-and-vinegar routine won't fully solve it long term — check the guide on descaling a washing machine naturally for the same acid-based approach applied to appliances, which shares the same root cause.
FAQ
What's the best natural way to unblock a drain? Bicarbonate of soda followed by white vinegar, sealed for 10-15 minutes and flushed with boiling water, clears most soap and grease clogs without any chemical cleaner.
Is vinegar or bicarbonate of soda better for a blocked drain? Neither works alone as well as the combination — bicarb loosens buildup and vinegar's acid reaction pushes debris free, so use both together rather than picking one.
How long does it take to unblock a drain naturally? Most slow-draining sinks clear in 15-20 minutes using boiling water, bicarb and vinegar; stubborn hair or grease clogs may need a second round plus a plunger.
Can boiling water alone unblock a drain? Boiling water alone clears light soap-scum blockages but rarely shifts hair clumps or solidified grease, so pair it with bicarb and vinegar for anything more than a slow drain.
Is natural drain unblocking safe for old pipes? Yes — bicarbonate of soda and vinegar are far gentler on ageing PVC and cast iron than caustic chemical drain cleaners, which can degrade pipe seals with repeated use.
How much does it cost to unblock a drain naturally? Bicarbonate of soda and white vinegar for one treatment cost under a pound in the UK as of 2026, against several pounds for a bottle of chemical drain cleaner.
When should I call a plumber instead of trying this myself? Call a plumber if the drain is still fully blocked after two natural treatment rounds plus plunging, or if water is backing up into other fixtures, which usually signals a blockage further down the main line.
Does this method work on toilets as well as sinks? Not reliably — toilets need mechanical force from a flange plunger rather than chemical reaction, since the trap shape limits how well vinegar and bicarb can reach the blockage.
One last thing
The fizzing reaction from bicarb and vinegar looks dramatic but does most of its actual work in the last five minutes it sits covered, not the first thirty seconds — resist the urge to flush early, because that's the single biggest reason people think the method doesn't work for them.
