Turbidity measurement is essential in water quality monitoring, but results can differ between standards. The two dominant international standards are ISO 7027 and EPA 180.1.
Light Source Differences
EPA 180.1 uses a tungsten filament lamp (white light, 400-600 nm). ISO 7027 uses a near-infrared LED (860±30 nm). The infrared source is unaffected by sample color but cannot detect certain small particles.
Detection Angle
EPA 180.1 specifies 90° scattered light detection (nephelometric). ISO 7027 also uses 90° as the primary detection angle, with additional angles permitted for specific applications.
Selection Guidance
EPA 180.1: recommended for drinking water and wastewater (historical data compatibility). ISO 7027: preferred for industrial process control and European markets (better interference rejection).