Domestic wastewater from homes without sewerage is discharged directly into the ground, rivers or streams, which generates health and pollution problems. Septic tanks are used as an on-site treatment by a significant fraction of the world's population. This study aimed to evaluate the efficiency of domestic wastewater treatment using septic tanks with baffles implemented in rural households. The septic tanks were built and evaluated as part of a research project, focused on decentralized domestic wastewater treatment systems at the rural level. The septic tanks operated with detention times of 4.44; 2.67 and 1.90 days. The data was obtained through five monitoring campaigns with a fortnightly frequency, taking water samples at the entrance and exit of each septic tank. After sample collection, concentration levels of BOD5, COD, total suspended solids (TSS), nitrates, and phosphates were ...