Inspect the Fitting Regularly

Checking the o-ring is in place and in good condition is cheap insurance. Double check after every fuel fill that he deck fill is closed correctly and snug tight. A damaged or missing o-ring or unsecured deck fill plate will allow water to enter the fuel tank.

The o-ring should be:

• correct size for the fitting
• not twisted
• not nicked or kinked

Water in a fuel tank can encourage the growth of HUM (Hydrocarbon Utilizing Microorganisms) which thrive in the fuel/water interface. In ideal conditions, a single cell weighing 1/1,000,000 of a gram can grow to 10 kilograms within 12 hours.

Best practice is to minimize as much as possible any water getting into the fuel tank(s), to drain the bottom of the tank of water from time to time and to change fuel filters on a regular schedule.