Clean water is essentially colorless when in thin layers. However, as the depth of the water increases, the water turns to blue and navy colors. Water in large bodies of water in seas and lakes generally appears blue. This blue color is not a reflection of the sky. In cloudy weather it is possible to see the water body in blue.

The penetration of water into different colors depends on the additives, water pollutants and the like. Water color changes according to the abundance and abundance of these substances.

Substances that give color to water are naturally occurring iron and manganese-like metallic ions, organic substances, aquatic plants and industrial wastewater. They give water different colors. For example, the limestone in the water causes the water to become turquoise. Iron and similar substances change the color of water to red and brown. Copper gives water a blue flame color. Algae in the water naturally change the color of the water to green.

Color determination in water is carried out to determine the actual remaining color of the water after the substances which give turbidity to the water are removed from the water. The sample taken by authorized laboratories is subjected to a number of processes and color determination is performed. Laboratories apply different methods to determine the color of water. For example,

• The water sample was compared with the colored solutions at a certain concentration.
• The water sample was compared with colored glass discs adjusted with platinum and cobalt solutions.
• Measurement by spectrophotometer

Today, the most commonly used method for color determination is spectrophotometer measurement. The basis of this method is to measure the color intensity of the sample taken on the spectrophotometer at the appropriate wavelength. The color value of the water increases as the pH of the water increases. Therefore, the pH of the color determination should be explained in the report.

Laboratories comply with TS EN ISO 5667-3 standard for sampling.