The HYDROKIT® is designed to indicate free water in excess of 30* ppm by changing the powder contained in the sample tube to a pink color. Thirty ppm is generally accepted as the maximum amount of water permissible when fueling aircraft. The HYDROKIT® is designed for “fail-safe” operation, with false negative readings unlikely. Almost any error in performing the test will indicate the presence of wet fuel. If the sample indicates the presence of excessive water, it is always a good practice to repeat the test on a second sample.