what organ is primarily responsible for water/mineral absorption?
It is the large not the small intestine. The small and large intestines perform different functions. The small intestine is where the most extensive part of digestion occurs. Most food products are absorbed in the small intestine. The large intestine is responsible for absorption of water and excretion of solid waste material. Food and waste material are moved along the length of the intestine by rhythmic contractions of intestinal muscles; these contractions are called peristaltic movements.