What is turbidity and how is it measured?

Turbidity measures cloudiness or haziness in a liquid caused by suspended particles that scatter light. Measurement uses a light source and detector positioned at 90 degrees (nephelometric) or 180 degrees (transmitted light). Results are in NTU (Nephelometric Turbidity Units) or FNU. Higher particle concentration = higher turbidity. Applications include drinking water quality (must be <1 NTU), wastewater treatment, beverage production, and pharmaceutical water systems. Turbidity indicates water clarity and treatment effectiveness.