@cireyes Typically turbidity is measured by the light-scatterring properties of the solution rather than absorbance. However, we have used the colorimeter for turbidity measurements and a couple of colorimeter tests (Sulfate and Potassium) are based on turbidity.
First, you will need to make a turbidity calibration curve so that you can measure your water sample. To do this, you will need to buy a turbidity standard of known NTU (Nephelometric Turbidity Units). This turbidity standard is a solution of formazin (suspended polymer particles). You can buy these online from many different suppliers such as Hach etc. I bought a 4,000 NTU standard in 2012 from Grainger, Part # 8UVJ9.
Using this NTU standard you can prepare a calibration curve in the range that you want to measure your sample. For example, in the graph below you can see that I made a range of 0 - 4000 NTU by diluting the standard with distilled water. The Red LED on the colorimeter is used to measure absorbance.
Once you have your calibration curve, you can measure your water sample to determine turbidity !