JACKSON TURBIDITY UNIT (JTU)

The JTU is a measurement of the turbidity, or lack of transparency, of water. It is measured by lighting a candle under a cylindrical transparent glass tube and pouring a sample of water into the tube until an observer looking from the top of the tube cannot see the image of the candle flame. The number of JTUs varies inversely and nonlinearily with the height of the sample (e.g., a sample which measures 2.3 cm has a turbidity of 1,000 JTUs whereas a sample measuring 72.9 cm has a turbidity of 25 JTU's).