If the bile acids are not reabsorbed into the bloodstream then they enter the large bowel (colon). Bile acids in the large bowel cause abnormally high levels of water and salts to get into the large bowel from the bloodstream.
This is a companion discussion topic for the original article at https://patient.info/digestive-health/irritable-bowel-syndrome-leaflet/bile-acid-diarrhoea