Turbidity
Allowable in SA 3-5 NTU . EPA Regulations =1 NTU
Suspension of particles in water interfering with passage of light is called turbidity. Turbidity is caused by wide variety of suspended matter which range in size from colloidal to coarse dispersions depending upon the degree of turbulence and also ranges from pure inorganic substances to those that are highly organic in nature. Turbid waters are undesirable from aesthetic point of view in drinking water supplies and may also affect products in industries. Turbidity is measured to evaluate the performance of water treatment plant.
Turbidity measured in NTU
Turbidity
Turbidity can be measured either by its effect on the transmission of light which is termed as Turbidimetry or by its effect on the scattering of light which is termed as Nephelometry. A turbidimeter can be used for samples with moderate turbidity and a Nephelometer for samples with low turbidity. Higher the intensity of scattered light higher the turbidity.
Contact Time and Low Turbidity: Are factors which are important in providing good disinfection using chlorine.
High Turbidity Causing an Increased Chlorine Demand: May occur or be caused by the inadequate disinfection of water
MCL for Turbidity: Turbidity is undesirable because it causes health hazards. An MCL for turbidity was established by the EPA because turbidity does not allow for proper disinfection.
The definition of turbidity according to Wikipewdia