Q. A brother wanted to know if it was permissible to give blood to blood banks so they can have a store just in case they need it?
A. Donating blood to another person is only allowed in the case of a necessity that requires it. Simply storing blood in the blood bank is not sufficient as a need for a Muslim to give blood to the blood bank. Hence, it is not permissible for a Muslim to donate his blood to the bank to be stored up.
And Allah knows best.
Mufti Waseem Khan