This is the 6675th most frequent Korean word.
위해
"For the sake of" or "for."
'위해' is used to express a purpose here, indicating that drinking water is done for the sake of health.
나는 건강을 위해 하루에 물을 많이 마신다.
I drink a lot of water every day for my health.
'위해' is employed to denote that the action of preparing the gift was intended for his friend's benefit.
그는 친구를 위해 선물을 준비했다.
He prepared a gift for his friend.
'위해' here denotes that the effort to reduce waste is aimed at benefiting the environment.