This ecological study examined the link between the completeness of Water, Sanitation and Hygiene (WaSH) facilities and diarrhea occurrence at the eco-zones of the Municipality of Abra de Ilog, Philippines. The absence of toilet facilities increases likelihood for diarrheal disease. The presence of a complete set of WaSH facilities a potable drinking water source, improved sanitary toilet facility and hand-washing facility at each household was important to lower diarrheal disease burden. Incomplete WaSH facilities lead to the occurrence of diarrhea irrespective of eco-zone. Nonetheless, having incomplete facilities is better than not having any facility at all.