Difference between 〜ておく and 〜っぱなし


I was wondering, what the difference is between 〜ておく and 〜っぱなし? For example,
how is the sentence お皿を洗いながらお水を出しっぱなしにしました。different from
お皿を洗いながらお水を出しておきました。? Thanks.




These two phrases are totally different, and please see other questions for
the general meanings.

～ておく ≒ do something in advance / in preparation for something. (Maybe you left
the place after that, but it's not necessary)

  * [What's the meaning of 〜ておきます?](https://japanese.stackexchange.com/q/12964/5010)
  * [What does the "~ておく" mean in "任せておく"?](https://japanese.stackexchange.com/q/5216/5010)
  * [What exactly is おく doing in 聞いておく?](https://japanese.stackexchange.com/q/2997/5010)

～っ放【ぱな】しにする

  * [What is the difference in terms of grammar between ～かける and ～っぱなし?](https://japanese.stackexchange.com/q/5860/5010)
  * [What is the difference in terms of grammar between きり and っぱなし?](https://japanese.stackexchange.com/q/5855/5010)

* * *

> お皿を洗いながらお水を出しっぱなしにしました。

This means you didn't turn off the water _while_ you were doing the dishes. A
typical response to this would be "Oh, please don't do that next time, let's
save water."

> お皿を洗いながらお水を出しておきました。

This is a bit strange sentence, but a typical response to this would be "Wait,
what do you mean? Maybe the water is still turned on? Stop it!" It's because
the sentence sounds somewhat like "While I was doing the dishes, I didn't
forget to turn on the water in advance", as if you had some other purpose you
didn't mention.

