Thanks a lot, dear Farid Benyahia and Constantinos V. Chrysikopoulos very your valuable comments. Best regards

HELLO

Turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates. The more total suspended solids in the water, the murkier it seems and the higher the turbidity.

FROM THIS LINK

www.lenntech.com/turbidity.htm

you can see this website

https://water.usgs.gov/edu/turbidity.html

The definition of Turbidity is the cloudiness or haziness of a fluid caused by suspended solids that are usually invisible to the naked eye. The measurement of Turbidity is an important test when trying to determine the quality of water. It is an aggregate optical property of the water and does not identify individual substances; it just says something is there.

Water almost always contains suspended solids that consist of many different particles of varying sizes. Some of the particles are large enough and heavy enough to eventually settle to the bottom of a container if a sample is left standing (these are the settleable solids). The smaller particles will only settle slowly, if at all (these are the colloidal solids). It’s these particles that cause the water to look turbid.

Regards,

Ata

Thanks a lot dear Ali hadi Ghawi., Hakim Lounici, Ata Rafiee. Best regards. 

Dear Nabeel Hameed Al-Saati 

Turbidity measurements are often used as an indicator of water quality based on clarity and estimated total suspended solids in water. 

You can have a look on it.

http://www.fondriest.com/environmental-measurements/parameters/water-quality/turbidity-total-suspended-solids-water-clarity/

Thanks and regards

Contributors have rightly defined what turbidity is. I just want to add comment in other to answer the other part of your question.

Even though, turbidity can give us an indication of how clean a water sample is, we cannot rely on it alone as a measure of water pollution. In fact what has caused turbidity to be high in a water sample might not even be a pollutant.

Thanks a lot, dear Monsuru Suara for this valuable hint. Best regards

Turbidity should not be included for pollution related studies. It's for water treatment related work only 

Turbidity is an indirect measurement of the suspended solids present in a water or wastewater sample. It is related to the interference of light transmission in a water sample. Actualy, the turdity indicates the intensity of ligh that is scattered by the particles present at an angle of 90º. Light play an important role on the processes that occurs in natural waters, so higher the turbidity is higher the impacts it causes on natural waters.

Thanks a lot, dear Gopalakrishnan, and Mierzwa. Best regards

I agree to the above definition. Turbidity is an important parameter in water treatment  than wastewater treatment because it indicates the extent of suspended matter in water ( in turbidity contributed by clay, silt, microorganisms other particles that has small settling velocity). Turbidity is the hiding site for microorganisms and chemicals and consumes a lot of disinfectants and removal of bacteria will be difficult, therefore turbidity has to be removed by settling and coagulation and flocculation and  filtration before disinfection.  In wastewater treatment, suspended solids (solids) are more relevant than Turbidity. Obviously, the content in wastewater is more organic in nature.

This arguments is somehow relative in the sense that, it will depend on the targeted quality of the water subjected to treatment. For consumption purposes, any level of turbidity may indicate or brand the water as polluted. However, if the that water is meant for treatment to avoiding chemical pollution or eutrophication when discharged into another water-body, then turbidity to some extent may not be regarded as a measure of pollution.