A simple visual test designed to give a quick indication of how turbid the sample is. Available in two sizes: 13″ and 26″.
Referenced in the WHO Water Quality Handbook and ISO 7027 is the Turbidity Tube method. Holding the tube near the bottom, water is poured into the tube. Looking directly down the tube from above continue to pour sample until the defined mark (cross or circle usually) is no longer visible. Read the turbidity value from the side of the tube.