On Mar 15, 10:02*pm, "dVaridel" wrote:
"terry" *wrote On Mar 15, 6:56 pm, Ron Garret wrote: It occurred to me today that in fifteen years of flying I have never
once found water in my fuel when I've drained my tanks. Not a drop.
Ever. Am I just lucky, or is this really as rare an occurrence as it
seems to be? (I fly in SoCal. Maybe that has something to do with it.)

Sounds unusual to me. But I live in a more humid place . *The most
likely time to find the odd drop is first flight of the day.
after air in the tanks has cooled down below dew point. *Keeping tanks
filled overnight will help, *but having dry air and warm climate will
reduce the likliehood.
terry.

Most likely in Qld, NT and the top end of WA. *Not so likely in Vic, SA and
south WA. *Possible in NSW.

yeh I am in Vic. I have seen it a few times, but only like 1 or 2
small drops. I have never really thought about it much but I have
just done a few calcs to see how much water would actually be in the
air.
At 30 deg C and 70%RH say in a 172 with half full tanks, you have
100 liters of air with a dew point of 24 deg C containing 2 g of
water. If that air cooled down to 10 deg C, approximated 1 g of
water would condense.
BUT, from memory I think that the solubility of water in fuel is
around 100 ppm, thus 100 litres of fuel could hold about 10 g of
water, so it would depend on how dry the fuel is to begin with.