Why do we need both a small and large intestine?

Why we need the small intestine is it absorbs 90% of nutrients of the food we eat. 
Large intestine is to absorb water from the remaining indigestible food matter and transmits the useless waste material from the body, 

Hope this helps. If you have anymore questions let me know :)  

Be by his side : ) make him feel better

Blood transfusions were rarely done and often fatal; they were outlawed until the nineteenth century.