Water quality typically determines diarrhea incidence rates, but findings vary widely across studies. This study want to synthesize those findings to find the relationship between water quality and diarrhea incidence. Method which utilized in this meta-analysis following PRISMA guidelines. The included study is observational studies (both case-control and cross-sectional studies) from databases including PubMed, ScienceDirect, Scopus, and Google Scholar. Only studies that report adjusted odds ratios (aOR) are included. Random-effects model was applied due to high heterogeneity. The results showed that water quality and diarrhea incidence are not significant (aOR = 0.63; 95% CI: 0.23–1.74; I² = 91.4%). Same results also found in subgroup analyses. This means that the relationship between water quality and diarrhea is not simple as it seems. Other factors such as sanitation, hygiene habits, and food contamination also influence diarrhea. Therefore, improving only on water quality to reduce diarrhea may not be sufficient. More integrated approach is needed to address diarrhea sustainably.