Where does juice and water come from?

My daughter regularly sings only two verses from the song "Farmer in the Dell" from Baby Macdonald: the chickens give us eggs and the cows give us milk. She launches into these solos in her beautiful, almost shouting, slightly out of tune glorious little voice. She has also deducted that milk comes from cows and eggs come from chickens. Brilliant, I know.

As an aside, we give our daughter watered down apple juice to drink. More affectionately referred to in our house as one word "juiceandwater".

One morning this week, after singing a rousing two-verse rendition of "Farmer in the Dell" and before taking a big sip of juiceandwater, my daughter turns to me and asks "Where does juiceandwater come from?" My husband and I look at each other in stunned disbelief. It was our first "tough" question that deserved a well thought out and reasonable answer. And I didn't want to over complicate things and give her more of an answer than was necessary. I tend to do that sometimes.

"Apple juice comes from apples"
"Apple juice comes from apples??!!"
"Yes, apple juice comes from apples"

And that was that. I never did get around to explaining water. We'll save that for next time.