We generally say 必要[ひつよう]があります or いります but it has several translations depending on the situation or the level of formality. *We can't use いります when the sentences has "to need" with "to (verb)" like your second sentence. Plants need water to grow. --> 水がひつようです / 水がいります。 She needs to go to the store. --> 行くひつようがあります。(You can't say 行くがいります.) I hope this helped you.

e.g. need a balanced diet バランスの取れた食事を必要とする need a day off 1日休みが必要である need to be admitted to hospital 入院する必要がある need to be negotiated 話し合う［交渉する］必要がある Hope this helps

I wish I knew, but if I can help you in German, I will do it in a heartbeat!

we can use たい form of the verb (1st and 2nd person) and たがる for (3rd person) form for these kinds of expression, example- I want to buy a car. 私は　車を　会たい　です。 she wants to go to the store.かのじょは　テパトに　いきたがっています。 I hope this'd be useful to you,all the best.

i am college student in china. sorry to bother you i hope we can exchange our language 。