Turbidity is the state of clarity of water due to suspended particles in the water, i.e. suspended solids, blocking the passage of light. The turbidity of the water is caused by silica, clay, organic substances and inorganic substances. These materials can be of very different sizes, from micron sizes to coarse particles. The turbidity is particularly high in rivers and rivers. This is due to the soils transported to the river by rain water. Turbidity in lakes and other stagnant waters is due to various water-soluble substances. In addition to this, organic pollution increases with domestic or industrial wastes carried by wastewater and rapidly increasing bacteria cause turbidity to increase.

The measurement of turbidity is mainly based on the principle of refraction, reflection, absorption or diffusion of light from the water sample by the turbidity.

Until recently, the standard method of measuring turbidity was based on the Jackson wax turbidimeter. However, this measurement method is not preferred today because it can measure above a certain value. Today, new methods have been developed for turbidity determination. The most commonly used method is the measurements made with electronic devices. The principle of these devices is to measure the amount of light transmitted in one direction after passing through the turbidity in the water and to compare it with the standard values. The turbidity values ​​obtained in the measurements are expressed as NTU (Nephelometric Turbidity Unit). However, it is expressed as JTU (Jackson Turbidity Unit) in TS 266 standard.

1 NTU is approximately 2,5 JTU. This means 2,5 mg silicon dioxide per liter. Silicon dioxide is a chemical compound containing silicon and oxygen.

Turbidity, ie turbidity tests, are also performed in the authorized laboratories within the scope of physical analyzes. During these studies, standards and test methods published by local and foreign organizations are followed. In this way, reliable and unbiased results are obtained.