Background: Universal access to safe drinking water and improved sanitation are paramount sustainable development goals. This is critical for overcoming several health challenges in developing countries. This study analyzed access to safe drinking water and sanitation in relation to diarrhea morbidity among children younger than 5 years in South Africa. Methods: The data were collected by Statistics South Africa during the 2014 General Household Survey and were analyzed using Probit regression. Results: Results showed that majority of the children from this study lived in houses, who access improved drinking water and sanitation, although only 29.68% of households paid for safe drinking water. Lack of water for washing hands was reported by 12.41%, while diarrhea was most prevalent among 1-year-old children (3.34%). Probit regression results showed that air and water pollution significantly increased diarrhea morbidity (P < 0.10), while it reduced with the child's age. Conclusion: It was concluded that addressing the problems of air and water pollution would reduce diarrhea morbidity among children younger than 5 years.