Given that water contamination is a major means of transmitting diarrheal disease, efforts to provide <answer>clean water supply and improved sanitation</answer> have the potential to dramatically cut the rate of disease incidence. In fact, it has been proposed that we might expect an 88% reduction in child mortality resulting from diarrheal disease as a result of improved water sanitation and hygiene. Similarly, a meta-analysis of numerous studies on improving water supply and sanitation shows a 22–27% reduction in disease incidence, and a 21–30% reduction in mortality rate associated with diarrheal disease.
What has cut the rate of diarrhea disease incidents? 
clean water supply and improved sanitation