世間知らずにもほどがある。井の中の蛙大海を知らず、ということかね。
I can't believe you're so clueless. You're like a babe in the woods.

井戸には少しの水も無かった。
There was no water in the well.

彼の仕事は井戸掘りからゴミの処理にまで及ぶ。
His tasks range from digging wells to getting rid of garbage.

今日は体調が悪い。あの井戸水が原因だ。
I feel out of sorts today. That well water is why.