The water in the toilet after stool is blood-colored as bloody stool, mostly seen in gastrointestinal bleeding, which is divided into upper gastrointestinal bleeding, middle gastrointestinal bleeding and lower gastrointestinal bleeding. 1. Upper gastrointestinal bleeding: bleeding volume > 1000 ml, blood in stool. It is mostly seen in peptic ulcer, rupture of fundic esophageal varices, upper gastrointestinal tract tumor, hemangioma, anastomotic ulcer, biliary tract hemorrhage, and anaphylactic purpura and other diseases. 2. Middle gastrointestinal bleeding: common causes include tumor, Crohn’s disease, drug injury, mesenteric artery embolism, ischemic enteropathy, intussusception, radiation enteritis and so on. 3. Lower gastrointestinal bleeding: common causes include hemorrhoids, anal fissure, intestinal polyps, colonic tumors, ulcerative colitis, ischemic enteritis, infectious enteritis, and so on. If you have bloody stools, please go to the hospital for a systematic and comprehensive examination in time to avoid delaying your condition.