Mixing vinegar and bicarbonate of soda

Does it work?

Does not work

Refuted for the general cleaning claim, on uncontested reaction chemistry rather than on any contested experimental result. The neutralisation is not in doubt, and the conclusion that the products clean less well than the reactants follows directly from it. The narrow drain-agitation use is recorded under limitations rather than being allowed to rescue the broader claim.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

Where not to use it

Why it works

The claimed mechanism is that the vigorous reaction lifts or loosens soil. What actually occurs is an acid-base neutralisation: acetic acid and sodium hydrogen carbonate react to give sodium acetate, water and carbon dioxide. The carbon dioxide is the foam. Once the reaction has finished, neither of the two active ingredients remains in any useful quantity — the acid that would have dissolved limescale has been consumed by the base, and the alkali that would have helped with grease has been consumed by the acid. The remaining sodium acetate solution is close to neutral and has no significant cleaning action.

Background

Pouring vinegar onto bicarbonate of soda produces an immediate and dramatic foaming, and that visible reaction is almost certainly why the combination became so widely recommended. The fizzing is carbon dioxide, and it is evidence of the two ingredients reacting with each other rather than with anything you wanted cleaned. Vinegar is useful because it is an acid; bicarbonate of soda is useful because it is a mild alkali and a fine abrasive. Combine them and the acid and the base neutralise, leaving a dilute solution of sodium acetate — a salt with no meaningful cleaning power — plus water and the gas that escaped. The mixture is weaker than either ingredient used on its own. The drain case is dealt with separately and, since Sprint 21, more cautiously: earlier wording here suggested the gas evolution could help dislodge loose debris in a pipe, which was CleaningHQ's own inference and not something any source in the register supports.

What it does not do

• The combination is weaker as a cleaner than either ingredient used separately, which is the opposite of what is usually claimed for it
• The visible fizzing indicates the ingredients reacting with one another, not with the soil
• No source in this register supports the idea that the gas produced does any useful mechanical work in a drain
• Mixing them in a sealed or nearly sealed container risks pressure build-up from the gas produced

What to use instead

• Detergent — A surfactant-based cleaner. The general-purpose answer for greasy and particulate soil, and the correct first choice far more often than any specialist product.
• Citric acid — A mild solid acid, widely used for descaling. Effective on limescale, and destructive to carbonate stone for exactly the same reason.
• Sodium bicarbonate — A mild alkali that is also a fine, soft abrasive. Its real usefulness is mechanical, and it is far weaker chemically than its reputation suggests.