The fastest and most consistent way of checking for water in your fuel storage tanks: Gasoila.
This product gauges phases separation in all mineral-based fuels including ethanol and methanol blends, diesel, kerosene, number 2 oil, and others. Due to Gasoila’s patented color-changing technology, this product works almost instantly, providing clear indication of water in your system (the paste will turn a bright yellow-green).
You may find Gasoila’s long list of applications is well-worth having a couple of tubes on hand. In addition to fuel tanks, you may use this product to detect water leakage in brake calipers, ASTs, USTs, and many other applications.