Turbidimeter is one tool that is functioning to measure water turbidity. Turbidimeter is a tool that has optical properties due to the dispersion of light and can be expressed as the ratio of the light. which reflected the light that arrives. Intensity of light reflected by a suspension is a function of the concentration if other conditions constant.
There are 2 types of Turbidimeter A commonly used today, namely:
o Bech top and portable used to analyze grab samples on Bech unit is usually used as a stationary laboratory instruments and are not intended to be portable.
o On-line instrument is usually installed in the field and constantly analyzing the sample stream spilled off from the sampling unit.
Figure 26. turbidimetry
The use of this turbidimetry which store samples or standards in a small jar / bottle samples. Before the appliance is used first set, where the numbers listed must be 0 or in neutral, then take the measurement by adjusting the measurement value by turning the regulator knob until the value shown on the screen at turbidimeter in accordance with standard values.
After the sample is inserted in place of existing sample measurement in turbidimeter, the result can be read directly turbidity measurement scale shown on the screen clearly. But the measurement of the sample must be done 3 times by pressing the repeatability of measurements for each repetition so that appropriate or valid measurement, and the results are immediately averaged.
The basis of the analysis turbidimetry measurements ditranmisikan light intensity as a function of the concentration of the dispersed phase, when the light is passed through the suspension of a portion of the radiant energy that falls dissipated by absorption, reflection, and the rest will ditranmisikan (Khopkar, 2003) .In tool practiced Turbidimeter this application of light entering through the water sample was then partially absorbed and partially transmitted, absorbed light is what is the level of turbidity.
So if more light is absorbed, the more turbid the liquid. According to WHO (World Health Organization). Stipulate that the turbidity of drinking water should not be more than 5 NTU, and should ideally be below 1 NTU. Based on the theory can be said that all the samples tested have met the eligibility for consumption because the level of turbidity (turbiditans) were below 5 NTU.