Something isn’t right. 5 gals of 10% ethanol fuel is 0.5 gals of ethanol. Chemistry says it won’t pull more than 10% water from air making it 0.05 gals water max (about 6 oz) at full saturation.
In a closed tank without constant air exchange, it calculates to be about a quarter ounce if the air was at 90% humidity when the tank was capped. Also, the ethanol is miscible with water so the water can’t separate as a distinct layer until the water exceeds its ability to hold.
Like I said...something isn’t right. The water is coming from somewhere else.
