In this study, the quality of collected rainwater at a downtown middle school rainwater harvesting system was evaluated by measuring physical, chemical, and microbiological parameters such as pH, dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), NO3, PO4, total coliform (TC), Escherichia coli, and some metals (i. e. Al, Cr, Mn, Zn, Cu, As, Cd, and Pb) (2003 to 2011). The analysis shows that the collected water quality is poor, which presents health, considering the high levels of bacterial indicators detected in the harvested rainwater, i. e. turbidity (1.4 to 15.5 NTU) and E. coli (120 and 35 CFU/100 mL in 2007 to 210 and 60 CFU/100 mL in 2011). This study shows that deteriorating water quality was caused by system contamination due to the absence of maintenance. Based on this study, proper operation and maintenance are generally the simplest and most effective ways of maintaining water quality.