How do you identify the detection of water in milk?

the easiest way of detecting water in milk is by testing the thickness of the milk by letting it touch the walls of a glass and see if the milk gives an opaque look to the glass ( which means less added water ) or if the milk just slides off leaving the glass transparent as soon as the milk touches the glass ( which means that water was added to the milk ). in industries, they use a lactometer to check the water addition. lactometer acts by measuring the specific densities of the milk and the value obtained on the calibrated scale will be then compared to that of the standard values.