Access to clean drinking water is still a challenge for a large part of the world. Contamination from bacteria, dissolved solids, heavy metals, and chemicals continues to cause health problems, especially in areas where lab-based testing is slow or unavailable. This paper presents the Smart Water Purity Alert System (SWPAS), a low-cost device built around an ESP32 microcontroller with two water quality sensors measuring turbidity and TDS (total dissolved solids). Sensor data is sent to a cloud platform, and whenever any reading goes beyond the safe limit, users receive an alert via a mobile app, SMS, or a local buzzer. The system was tested on three water samples and correctly identified contaminated water without triggering false alarms on safe samples. Alerts were delivered within 2 to 4 seconds of a threshold breach, and the total hardware cost stayed under ?4,000.