expression, ichidan verb
a small leak will sink a great ship
Proverb meaning that a tiny oversight or minor flaw can lead to a major disaster. Often used as a warning to pay attention to small details.
千丈の堤も蟻の一穴より崩れるというから、小さなミスも見逃してはいけない。
As the saying goes, a small leak will sink a great ship, so you must not overlook even minor mistakes.
A variant of the same proverb with a slightly different wording, but the meaning is identical.
A classical Chinese proverb (千里之堤，潰於蟻穴) adopted into Japanese. The literal meaning is 'even a thousand-jō embankment crumbles from a single ant hole.'