Bicarbonate of soda and vinegar down a drain

Does it work?

Unresolved

Unresolved, and split deliberately. The chemical half of the claim is refuted by settled chemistry the register already holds. The mechanical half is untested by anything in the register, and calling it refuted would assert a finding nobody has made. Recording the two halves at different strengths is the point of assessing the hack rather than adjudicating it.

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

The proposed mechanism

The explanation below is what is offered for this technique. CleaningHQ has not found evidence establishing that this is what actually happens, and says so rather than presenting a plausible story as a finding.

The claimed mechanism has two parts and they need separating. The chemical part is that the reaction attacks the blockage; that is established to be wrong, because the reaction is between the two ingredients and consumes both, leaving sodium acetate solution. The physical part is that the evolved carbon dioxide agitates or pressurises the obstruction loose. That part is UNRESOLVED rather than refuted: it is not chemically absurd, but no source in this register has tested it, and a domestic drain is open to atmosphere at both ends, so there is no obvious reason the gas should preferentially act on the blockage rather than escape past it. CleaningHQ will not convert a plausible-sounding physical story into a recommendation.

Background

This is the highest-demand hack in the register, and the counter-claim — that you should never do it — recurs almost as often as the hack itself. Both deserve an answer, and the honest one is narrower than either. What happens chemically is settled: acetic acid and sodium hydrogen carbonate neutralise each other, giving sodium acetate, water and carbon dioxide. The foam is the gas. When it stops, the acid that could have dissolved scale has been consumed by the base, and the alkali that could have helped with fat has been consumed by the acid. What is left in the pipe is a dilute, near-neutral salt solution. Whether the gas does mechanical work is a separate question, and CleaningHQ does not know. No source here tests it, and an open drain is not a sealed vessel. Earlier wording suggested the fizzing might dislodge loose debris; that was inference, and Sprint 21 removed it. What IS established is the cause of the problem being treated. Slow kitchen drainage is usually fats, oils and grease solidifying on the pipe wall, and an extension service states that hot water and soap do not eliminate them. A near-neutral salt solution has less claim on fat than soap does.

What it does not do

• The two ingredients neutralise each other, so the mixture is a weaker cleaner than either used alone
• Nothing in the mixture addresses fats, oils and grease, which is what usually slows a kitchen drain
• Whether the gas does any useful mechanical work in a pipe is untested by any source in this register
• It does nothing about a physical obstruction such as hair bound up with soap residue
• It leaves standing liquid in a drain, which matters if any other product is added afterwards

What to use instead

• Dry soil removal — Taking the loose material away before any liquid touches it. Skipped almost universally, and it is the step that decides whether the rest works.
• Household drain — The one thing in a house you clean without being able to see, reach or test it — which is why almost every drain hack is really a guess.