Because it purifies your blood, for you and if they go, you end up with dirty, unhygienic blood.
Additional information:
You don't necessarily die immediately. Many lives are prolonged by kidney dialysis.
You can only die if both are not working BUT if one of the kidneys still work then you wont die.
Did you mean organs? All of them. If you lose your kidneys, you die.
you die
You would die
you die ;)
You die, funny actually
The kidneys do not effect your lungs even if they don't work. However, you'll die shortly after your kidneys fail.
if we didn't have 2 kidneys you will die but if you have 1 kidney you will stay alive.
Big kidneys do not cause death. Kidneys that do not work cause death.
you die
you will die
If the fish are fresh water fish the kidneys would not work. The fish would die.