What unit is used to measure turbidity in water?

Turbidity in water is measured using Nephelometric Turbidity Units (NTU). This measurement quantifies the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye. The NTU scale is specifically designed to reflect the light scattering properties of suspended particles when a beam of light is passed through the water sample.

Using NTU allows for a standardized approach when assessing water quality, which is crucial for meeting health and safety regulations concerning drinking water, recreational water, and wastewater treatment. The measurement is made using a nephelometer, an instrument that detects the amount of scattered light at a specific angle relative to the incident light.

Other units mentioned, such as parts per million (PPM) and milligrams per liter (Mg/L), typically measure concentration levels of substances but do not directly quantify water clarity as NTU does. Calcium carbonate equivalence serves a different purpose by measuring the concentration of calcium carbonate in water, which is not relevant to turbidity assessments. Therefore, NTU is the appropriate and widely accepted unit for indicating turbidity levels in water.