The turbidity test is designed to give a measure of the suspended solids content of the final effluent. It is also useful in following the day to day variation in quality of sewage and effluent.

The Palintest Turbidity test uses a specially calibrated plastic tube. This provides the simplest possible method for performing this important test. The PT 513 includes a tube graduated at 30-500 turbidity units. A double length tube (PT 513) with additional graduations from 5 to 25 turbidity units is also available. The palintest turbidity tubes were calibrated by the department for public health engineering, University of Newcastle upon Tyne.

Sometimes these are referred to as Jackson Tubes