Short answer
As a clog fix, the evidence is weak. The two react into water, sodium acetate and carbon dioxide; the fizz is the gas escaping, not scrubbing. Any cleaning comes mostly from leftover baking soda and the hot water you flush with. It is fine as gentle upkeep. For a sink that is actually blocked, pull the stopper, plunge, or clean the P-trap.
What actually happens in the drain
Baking soda is sodium bicarbonate, a mild base. Vinegar is dilute acetic acid. When they meet, they neutralize each other and make three things: water, sodium acetate (a salt) and carbon dioxide gas. The gas is the fizz.
A chemistry lecturer at the University of Tasmania, writing in The Conversation, puts it plainly: the fizz is mostly show. The bubbles are gas escaping, not scrubbing the pipe. In chemistry terms, mixing the two neutralizes both, so each does less than it would alone. Whatever cleaning happens comes largely from any leftover baking soda that did not react, plus the hot water you pour after it.
Does it unclog a drain?
We know of no controlled study of baking soda and vinegar on blocked drains. So the honest answer is that the evidence is weak. Treat any page that quotes a success rate with suspicion.
What we can say from the chemistry and from how clogs form:
- Hair clogs, the usual bathroom problem, are a tangle held together by soap. Bubbles do not untangle hair. Pulling the stopper does. See how to unclog a bathroom sink.
- Grease clogs in a kitchen trap are a solid plug. A cup of fizz sitting on top of standing water barely reaches it. Plunging or cleaning the trap does. See how to unclog a kitchen sink.
- Light film and odor on the pipe walls is where it has the best chance, mostly thanks to the hot water rinse.
Where it is fine: gentle upkeep
As a monthly freshen-up on a drain that already flows, it does little harm. Baking soda is cheap, vinegar is mild, and the hot water flush does real work on soap film. Just do not expect it to fix a sink that has stopped draining, and do not let it delay a real fix.
The routine people use
This is the common method, presented as maintenance on a drain that flows, not a clog remedy.
Run hot tap water for a minute
Warm the pipes and rinse away loose debris. Use very hot tap water, not boiling water, if your drain pipes are PVC or your sink is porcelain or fireclay.
Pour in about half a cup of baking soda
Pour it straight into the drain opening. With a pop-up stopper, lift it out first so the powder goes down the pipe instead of piling on the stopper.
Add about half a cup of white vinegar
Pour the vinegar in after the baking soda. It will fizz for a minute or two. Covering the drain with a plug keeps the foam in the pipe instead of in the bowl.
Wait 15 to 30 minutes
The fizz is over quickly. The wait gives the leftover baking soda time to sit against the pipe walls.
Flush with hot tap water
Run very hot tap water for a minute or two to rinse everything through. Again, hot tap water rather than boiling on PVC or porcelain.
What works better for a real clog
| Clog | Try this first | Then |
|---|---|---|
| Bathroom sink, slow or stopped | Pull and clean the pop-up stopper | Plastic barbed strip, plunger with the overflow sealed, clean the trap |
| Kitchen sink, standing water | Cup plunger with the other drain blocked | Clean the P-trap, then a hand snake |
| Slow drain, no clog found | Check the stopper height | See slow sink drain fixes |
| Smell, no clog | Scrub the stopper and overflow | See sink drain smells |
Most bathroom clogs are hair and soap at the stopper (Ask the Builder), and sealing the overflow while you plunge, or blocking the other drain in a double sink, keeps the pressure on the clog (The Home Depot).
Tools that do more
For a side-by-side of plungers, strips, snakes and cleaners, see the best drain cleaners and snakes.
About boiling water
Many baking soda recipes end with a kettle of boiling water. Skip that step if your drain pipes are PVC, which is common under modern sinks, or your sink is porcelain or fireclay. Plumbing guides note PVC is rated for continuous use only up to about 140°F, and porcelain can crack from a sudden temperature change. Very hot tap water gets most of the benefit with less risk.
Questions people ask
Does baking soda and vinegar unclog a drain?
We know of no controlled study showing it clears drain clogs, so the evidence is weak. The reaction mostly turns the two into water, sodium acetate and carbon dioxide. It may loosen light film, but a plunger, a barbed strip or cleaning the trap is far more likely to clear a real clog.
How long do you leave baking soda and vinegar in a drain?
The common routine is about 15 to 30 minutes before flushing with hot tap water. Longer does not make the reaction stronger: the fizz is over within a minute or two.
Can I pour boiling water down the drain after baking soda?
Not if your drain pipes are PVC or your sink is porcelain or fireclay. Use very hot tap water instead. Many plumbing guides note PVC is rated for continuous use only up to about 140°F.
Can I use baking soda and vinegar after a chemical drain cleaner?
No. Never combine homemade remedies with chemical drain cleaners or put one down a drain that still has the other in it. Follow the chemical cleaner’s label, flush it fully, and use one approach at a time.
Is baking soda alone good for drains?
Baking soda is a mild alkali and a gentle abrasive. Rinsed down with hot water, it may help with light buildup as part of regular upkeep. It will not dissolve a hair clog.
What works better than baking soda and vinegar?
For a bathroom sink, pull and clean the stopper, then use a plastic barbed strip or a plunger with the overflow sealed. For a kitchen sink, plunge with the other drain blocked or clean the P-trap. A hand snake handles clogs past the trap.
Sources
Last reviewed October 12, 2026. Parts, sizes and listings change; check the product details before you buy, and follow the maker’s instructions.