The amount of insoluble matter present in drinking water is an essential quality indicator. Silt, sand, bacteria, spores, and chemical precipitates all contribute to the cloudiness or turbidity of water. Drinking water (DW) which is highly turbid can be unpalatable and unsafe. Consumption of even low concentrations of certain bacteria and other microorganisms can cause serious health effects. Consequently, an accurate and sensitive measurement of turbidity is vital for ensuring that drinking water is free of these contaminants. Public health and safety organizations throughout the world have recognized the importance of measuring drinking water quality through turbidity. The US EPA requires turbidity monitoring for all produced drinking waters. The EU Drinking Water Directive identifies turbidity as one of several fixed monitoring parameters which must be measured for all water intended for human consumption. The WHO recommends monitoring turbidity frequently and at multiple points throughout the treatment process. While regulatory limits vary across national borders, there is widespread agreement that reliable turbidity monitoring is an essential component of drinking water production.