The part of the digestive canal involved with the faeces formation is Rectum. Before the undigested waste products are deposited in the rectum, the large intestine absorbs water and salts, which transforms the wastes products into a solid mass. This solid mass is stored in the rectum before being expelled from the body.
On average, an adult human expels around 100gms to 250 gms of faeces every day. Explore more about the process of excretion or other related topics by registering at BYJU’S.