For what it's worth, I've cleaned fuel tanks four times without incident and still convinced this is the best way. Completely fill the tank with water and with a friend, slosh and slosh then drain contents in a clean white bucket. You'll see anything fall out. I repeated this process several times.

I then emptied all the water and left the wings to dry by elevating it allowing the remaining water to drip out over a week or so. I used Kleenix to wipe just inside the big drain hole to check for moisture remaining. There was none after a week and I taped a fine screen over the gas holes to keep dust out.

I suppose one could do a final slosh with 100LL, but the tanks dried completely and there was no need to buy gas and dispose of it with contaminants. Even with thorough sumping and checking gascolator prior to first flight, no water was ever present.

Hope this helps,
Don Barnes
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