The work explains and contrasts land-based natural purification with engineered methods for treating town sewage, detailing soil and subsoil roles, biological aerobic processes, and evaporation and plant uptake on sewage farms. It examines artificial approaches—septic tanks, intermittent and continuous contact beds, chemical precipitation and sludge management—discussing microbiology, oxygen consumption, nitrate formation and removal, effluent quality, and operational practice. Case studies, experimental results and contemporary commission reports inform practical recommendations on site selection, leveling, cropping, automatic appliances and management, with attention to public health implications and the need to balance nature's capacities with engineered supplements where land or conditions limit natural treatment.