Turbidity refers to the concentration of undissolved, suspended particles present in a liquid measured in Nephelometric Turbidity Units (NTU). It is important to note that turbidity is a measure of sample clarity and not colour. Water with cloudy or opaque appearance will have high turbidity, while water that is clear or translucent will have low turbidity. High turbidity value is caused by particles such as silt, clay, microorganisms, and organic matter. By definition, turbidity is not a direct measure of these particles
but rather a measure of how these particles scatter light.

Turbidity is a very complex analytical measurement which can be affected by many factors. Some are inherent in the instrument’s design such as angle of detection, light beam aperture, incident beam wavelength and colour sensitivity of the photocell. However, there are other factors such as stray light, air bubbles and care of vial, which can be prevented through proper care of equipment and accessories.

The Eutech CyberScan TB 1000 Turbidimeter meets the performance criteria specified by US EPA
method 180.1 for NTU measurement. In addition, the infrared light source models meet the ISO
7027 standards of measurement. The Eutech Waterproof Portable TN 100 Turbidimeter
designed for testing on-the-go features laboratory accuracy and excellent repeatability with US EPA
approved non-formazin standards and is ISO 7027 compliant.