ISO 7027-1:2016规定了使用光学浊度计或浊度计测定水浊度的两种定量方法: a） 浊度法，漫辐射测量程序，适用于低浊度水（例如饮用水）； b） 浊度法，测量辐射通量衰减的程序，更适用于高浊度水（例如废水或其他浑水）。 根据第一种方法测量的浊度以浊度单位（NTU）表示。结果通常介于<；0,05 NTU和400 NTU。根据仪器设计，它也适用于浊度较高的水。 NTU和formazin散射比浊单位（FNU）在数值上是等价的。 第二种方法测量的浊度以甲嗪衰减单位（FAU）表示，结果通常在40 FAU到4000 FAU之间。

ISO 7027-1:2016 specifies two quantitative methods using optical turbidimeters or nephelometers for the determination of turbidity of water: a) nephelometry, procedure for measurement of diffuse radiation, applicable to water of low turbidity (for example drinking water); b) turbidimetry, procedure for measurement of the attenuation of a radiant flux, more applicable to highly turbid waters (for example waste waters or other cloudy waters). Turbidities measured according to the first method are presented as nephelometric turbidity units (NTU). The results typically range between <0,05 NTU and 400 NTU. Depending on the instrument design, it can also be applicable to waters of higher turbidity. There is numerical equivalence of the units NTU and formazin nephelometric unit (FNU). Turbidity measured by the second method is expressed in formazin attenuation units (FAU), results typically range between 40 FAU and 4 000 FAU.