Where does this come from, and can I check it?

Trapped water stops sewer gas from rising back up through the drain. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

The U-bend under a sink holds a water seal

Trapped water stops sewer gas from rising back up through the drain A waste pipe drops from the basin, curves upward and drops again, leaving a pool in the dip. That pool is the seal: gas cannot pass a column of water roughly 50 to 75 millimetres deep. The shape is called a trap, and it also catches dropped rings before they reach the sewer. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Encyclopaedia Britannica

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: plumbing, drains, water

The U-bend under a sink holds a water seal: the short answers

Where does this come from, and can I check it?: Trapped water stops sewer gas from rising back up through the drain. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.