Enhanced NTU Measurement by Modified Turbidity Sensor: A Cost-Effective Approach for Household Water Quality Monitoring

Water turbidity monitoring is necessary for water quality check in household applications. Commercial nephelometric sensors measuring turbidity using multiple angle scattered light are too expensive for domestic appliances, while standard low-cost sensors measure only direct light transmission, neglecting scattered light. This paper presents a simple but effective modification to existing standard sensors by adding a phototransistor at 90° to capture scattered light. The work focuses on the data acquisition and fusion methodology that combines transmitted and scattered light signals to produce an enhanced turbidity reading. The modified sensor demonstrates enhanced capability, showing readings up to 5.0 NTU compared to 3.6 NTU maximum for unmodified sensors—a 38.9% improvement. Experimental validation over 24-hour monitoring confirms enhanced sensitivity and reliability, with statistical analysis revealing a strong linear correlation (r = 0.89) between sensor outputs . The scattered light contribution analysis shows it provides 30–60% of the total signal, with increasing importance at low turbidity levels. The modification adds less than ₹55 to sensor cost, bridging the gap between expensive commercial and basic household turbidity sensors. This data-driven approach enables smarter water usage in appliances and potentially reduces water and energy consumption.