To throw the baby out with the bathwater is an idiom which means to lose something important while trying to get rid of unwanted things. The idiom is undefined as to whether the act of discarding the ‘baby’ is intentional or unintentional. In other words, you could choose to throw away the valuable or accidentally lose it.
The phrase is directly translated from a German proverb dating from at least 1512. In German it reads das Kind mit dem Bade ausschütten. It was paired with an illustration of a woman dumping a tub of water and an infant falling out into the river.
There are several myths about how the idiom was created, including speculation on the bathing practices of people in the Medieval times. However, there is no evidence to promote one theory over another.
Examples
Perhaps the moves by the ATO were to avoid these scenarios from occurring, but the baby has been thrown out with the bathwater. [The Australian]
“They don’t want to make the distinction between one independently owned franchise location and another. They’re throwing the baby out with the bathwater with this regulation.” [The Washington Times]
While I appreciate no Staffordshire Library closures are foreseen in new streamlining proposals for the library service, I still fear the baby may well be thrown out with the bath water! I understand that books are not borrowed so much, and old fashioned library use is shrinking, but the ability to read a physical book is still an essential learning experience for the young. [Tamworth Herald]