 [ Symptoms ] when i try to drink any substantial amount of water i feel sick and get diarrhea [ Disease ] having diahrrea means you need more fluids but if drinking water increases it then either possibities are there you are having an intestinal bacteria that causes your dihrrea when they have enough waterbury n gut this can be ruled out by a stool analysis or the water you drink does not contain the enough electrolytes and sugar in this case you need to lower water intake and increasing other fluids as fresh juices and sport beverages