NTU is a globally accepted method of measuring the clarity of water. The device is accepted by the EPA and other organizations. IDFB approved the use of the NTU machine as a potential replacement to the visual measuring system that uses a glass tube.

The measurement theory is different in the two systems, but similar conclusions can be made.

The following is an approximate conversion table from NTU to mm. This table was created with a curve of results for 4,000 samples. Double tests were completed in 2,000 samples for both the NTU and the mm glass tube system.

For a given NTU value, a wide range of mm results were found. The reason for the wide range is both the different measuring system and the problems of a subjective, visual test method.

If NTU is 1.9 or less then mm= 1000+ If NTU is 20.0 or more then mm = 100 or less

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