What does Nephelometric Turbidity Unit (NTU) measure?

Nephelometric Turbidity Units (NTU) specifically measure turbidity in water, which refers to the cloudiness or haziness caused by large numbers of individual particles that are generally invisible to the naked eye. Turbidity can be caused by various substances, including sediments, organic matter, plankton, and other particulates in the water.

The measurement is derived from the way light is scattered by these particles when illuminated by a light source. In a nephelometric method, a light beam passes through the water sample, and the amount of light scattered at a specific angle is measured. This measurement indicates the concentration of suspended particles in the water, providing a clear understanding of water quality and transparency.

Proper turbidity levels are vital for water treatment processes, as high turbidity can hinder disinfection and may affect the taste and safety of drinking water. Understanding NTU helps in monitoring and regulating water quality in various water supplies, making it crucial for water operators.