Water without sanitation and hygiene doesn't work, because the clean water gets contaminated so easily. When people defecate in the open -- as is customary in many areas without proper sanitation facilities -- the rain will wash fecal matter into ponds, rivers, and other water sources, spreading disease and bacteria.

Also, if people are not taught how disease is spread, the clean water could easily be contaminated through dirty water containers, dirty hands, and dirty dishes. These practices are a major cause of diarrhea, which contributes to many preventable child deaths. Education about hygiene is very important, and implementing sanitation practices, such as latrines and places to contain human waste, is also foundational.