The Myth of Condensation in Fuel Tanks

[Babyboomer]

Frequently we hear it said that the cause of water in fuel tanks is due to condensation. I have long doubted this assertion but the issue has come up so frequently that I was finally motivated to try prove to the point. The basis of my belief or assumption is that:
http://www.yachtsurvey.com/myth_of_condensation_in_fuel_tanks.htm

[Sea Dumpster]

I think the math is flawed in this report. They are converting grams (weight) to ounces (volume) and plugging it into a volume formula.

Paul

[Black_Diamond]

Several items not considered in the theory:

1.  Air in a fuel tank is not static, it vents in/out as the temperature and air pressure changes.  Thus the quantity of water is always replenished in the air.
2.  Gasoline with ethanol is capable of 'pulling in' water much better than gasoline alone
3.  Diesel is famous for absorbing water when left static (not being used and refilled), thus the work to scrub the fuel and keep out bacteria
4.  Fuel pickups are not pulling from the pure bottom of the tank, so water can accumulate over time.

[Capt Ron]

I go on what works, been boating for fifty years and always filled tanks to the brim for storage, never an issue.