Turbidity in water is caused by suspended and colloidal matter and is an expression of the optical property that causes light to be scattered and absorbed rather than transmitted. This method uses a nephelometer to measure turbidity. A nephelometer is a turbidimeter with a scattered-light detector at a 90° angle to the incident beam. Possible interferences with this method include floating debris and coarse sediment which settle out rapidly. Highly colored samples can give artificially low turbidity values. The method has a detection limit of 0.1 NTU.
Clesceri, L. S., A. E. Greenberg and A. D. Eaton. 1998. Method 2130 B. (Turbidity-Nephelometric Method). Standard Methods for the Examination of Water and Wastewater, 20th Edition.